venee

Optimum life-time management of coronal fractures in anterior teeth: A review of crowns, veneers, composite resin restorations and intra-coronal bleaching

July 2008

Author: Dr Sarah Clark

Shirley

Typewritten Text

Edited by: Jonathan Leichter and Karl Lyons

Shirley

Typewritten Text

Optimum life-time management of coronal fractures in anterior teeth

Important Note

This evidence-based review summarises information on treatments utilised for the restoration of fractured anterior teeth: dental crowns, veneers, composite resin restorations and intra-coronal bleach. It is not intended to replace clinical judgement, or be used as a clinical protocol. A reasonable attempt has been made to find and review papers relevant to the focus of this report. It does not claim to be exhaustive. This document has been prepared by staff of the ACC, Evidence Based Healthcare Advisory Group. The content does not necessarily represent the official view of ACC or represent ACC policy.

Accident Compensation Corporation Evidence Based Brief Report ii


Executive Summary Background: A 2006 review of a sample of ACC crowns for prior approval treatments on

anterior teeth revealed that up to 90% of crowns were to be placed inappropriately and

unnecessarily, and highlighted a need for improved guidelines for the treatment and

restoration of fractured anterior teeth. This evidence based healthcare (EBH) review of

crowns, veneers, composite resin restorations and intra-coronal bleaching was undertaken

as a first step in the development of new ACC guidelines for the restoration of fractured

anterior teeth.

Search strategy: A systematic search of major literature databases (Cinahl, Cochrane

Central Register of Controlled Trials, Current Contents, Embase, Medline, Index New

Zealand, PubMed, and the Science Citation index) was performed using a strategy aimed

at sensitivity rather than precision. Key words describing the four interventions (crown,

veneer, composite resin restorations, intra-coronal bleaching) were used to create a master

database which was then searched for studies of different types and focus as follows:

randomised controlled trials (RCTs) and systematic reviews, appropriate or inappropriate

utilisation, dental trauma, and safety/adverse effects. The data range was limited to

references from 1987 onwards. Bibliographies of retrieved articles were hand-searched to

identify any further studies of relevance.

Selection criteria: Clinical studies about anterior teeth, of any study type except for

individual case studies, published from 1987 onwards were considered; but there were

unique selection criteria for each intervention. Composite resin studies were limited to

traumatised teeth, and bleach studies were limited to discoloured teeth, whereas crown

and veneer studies encompassed the general population. Shorter follow-up periods were

accepted for composite resin and bleach studies, whereas follow-up periods were limited

to 5 and 4 years respectively for crown and veneer literature.

Main results: One hundred and forty one references were retrieved, and of these, 92 were

selected for critical appraisal. Twenty six studies were included in this review: 10 for

crowns, 8 for veneers, and 4 each for composite resin restorations and intra-coronal

bleaching. Overall, the quality of the literature was poor by evidence based standards, and

none of the studies were directly comparable because of variations in almost every aspect

Accident Compensation Corporation Evidence Based Brief Report iii


of the studies. The most commonly reported main outcome measure for crowns, veneers

and composite resin restorations was survival or failure rate over time; the outcome

measures for bleach studies were success/failure of the whitening process, patient

satisfaction and colour stability.

Conclusions: The predominant outcome measure reported in the literature was survival

of restorations and the results of this review show that there is a large variation in the

survival rate of crowns (43-95%) and veneers (53-96%) over 10-12 years. The survival

rate of composite resin restorations is poor, and patients should expect to require re-

treatment within 2 to 7 years. Intra-coronal bleaching is effective in at least 60% of cases.

Some patient factors (e.g. age, oral health) were associated with a higher risk of premature

failure of dental crowns, veneers and composite resin restorations. However, there is

insufficient evidence to establish guideline-quality patient and tooth selection criteria that

relate to specific types of fracture or extent of tooth avulsion.

Recommendations: The guideline development panel should consider incorporating the

following recommendations into the guidelines. These recommendations arise from a

synthesis of all the evidence presented about survival of tooth restorations, and patient risk

factors. They also incorporate the philosophies of striving for conservation of tooth tissue,

and choosing a treatment plan that maximises the life-time potential of teeth.

1. When the primary indication for restorative treatment of fractured, non-vital

anterior teeth is discolouration, intra-coronal bleaching should be the first

treatment choice because it is effective in at least 60% of cases, has only one

harmful side effect of low incidence, and does not limit subsequent treatment

choices.

2. Unless indicated otherwise, patients <30 yrs should be treated conservatively with

composite resin build-up, or reattachment of the avulsed fragment if available.

This would be done with a clear understanding that these restorations are likely to

require replacement within 7 yrs, but that this can be done at least once before the

less conservative treatments of veneers and/or crowns need be considered.

3. In cases where either veneer or crowns are indicated, a veneer should be the first

treatment choice for the following reasons:

Accident Compensation Corporation Evidence Based Brief Report iv


the survival rate of veneers appears to be better than for crowns.

a high percentage of failures are repairable, further extending the life of the

restoration.

there is greater conservation of tooth tissue, and consequently a retention of

some options for future treatments if the veneer fails.

4. Veneers should not be applied to teeth with large amounts of lost tooth tissue. The

definition of ‘large amounts’ remains to be decided. It should also be noted that a

relative contraindication for veneers is poor oral health and a high caries rate.

Accident Compensation Corporation Evidence Based Brief Report v


Acknowledgements

The author wishes to acknowledge assistance of Susan Bidwell, Information Specialist,

New Zealand Health Technology Assessment (NZHTA) in carrying out the literature

search.

This evidence based review by peer reviewed by the following people:

Mr Karl Lyons (BDS MDS Cert Maxillofacial Pros FRACDS)

Senior Lecturer/Prosthodontis, Department of Oral Rehabilitation, School of Dentistry,

University of Otago, New Zealand

Professor Lindsay Richards (BDS BScDent PhD MRACDS(Prosth) FICD FADI)

Dental School, The University of Adelaide, Australia

Glossary of Terms

CDA/Ryge California Dental Association/Ryge criteria for evaluating clinical quality and

performance

ANOVA Analysis of Variance

Accident Compensation Corporation Evidence Based Brief Report vi


Table of Contents Executive Summary ................................................................................................................iii

Acknowledgements.................................................................................................................. vi

Glossary of Terms ................................................................................................................... vi

Table of Contents ...................................................................................................................vii

1 Background..................................................................................................................... 11

2 Objectives........................................................................................................................ 12

3 Methodology ................................................................................................................... 13 3.1 Criteria for selecting studies for this review ....................................................... 13

3.2 Criteria for excluding studies from this review................................................... 13

3.3 Search Strategy and information sources ............................................................ 14

3.4 Methods of the review......................................................................................... 15

3.5 Description of studies ......................................................................................... 15

4 Crowns............................................................................................................................. 17 4.1 Health Technology .............................................................................................. 17

4.2 Results ................................................................................................................. 17

4.2.1 Description of Studies ................................................................................. 17 4.2.2 Clinical Outcomes ....................................................................................... 18 4.2.3 Incidence and cause of crown failure .......................................................... 22 4.2.4 Adverse effects ............................................................................................. 24 4.2.5 Patient Selection Criteria: Risk Factors for longevity .................................. 27 4.2.6 Cost ............................................................................................................. 27

4.3 Discussion ........................................................................................................... 27

4.3.1 Methodological Quality ............................................................................... 27 4.3.2 Clinical Outcomes ....................................................................................... 29 4.3.3 Safety and adverse effects ............................................................................ 31

4.4 Summary of Evidence.......................................................................................... 31

4.5 Conclusions......................................................................................................... 32

4.6 Appendix 1: Evidence Tables for Crowns ........................................................... 33

5 Veneers ............................................................................................................................ 43 5.1 Health Technology .............................................................................................. 43

5.2 Results ................................................................................................................. 43

5.2.1 Description of studies.................................................................................. 43 5.2.2 Clinical Outcomes ....................................................................................... 44 5.2.3 The cause of veneer failure .......................................................................... 46 5.2.4 Adverse effects ............................................................................................. 49 5.2.5 Patient Selection Criteria - Risk Factors for longevity................................. 50

Accident Compensation Corporation Evidence Based Brief Report vii


5.2.6 Cost of Veneers............................................................................................ 50 5.2.7 Methodological Quality ............................................................................... 50 5.2.8 Clinical Outcomes ....................................................................................... 52 5.2.9 Safety and adverse effects ............................................................................ 53 5.2.10 Implications for outcomes over a lifetime ................................................... 53


5.4 Conclusions......................................................................................................... 55

5.5 Appendix 2: Evidence Tables for Veneers........................................................... 56

6 Composite resin restorations......................................................................................... 64 6.1 Health Technology .............................................................................................. 64

6.2 Results ................................................................................................................. 64

6.2.1 Description of studies.................................................................................. 64 6.2.2 Clinical Outcomes ....................................................................................... 65 6.2.3 Adverse effects ............................................................................................. 69 6.2.4 Patient Selection Criteria - Risk factors for longevity.................................. 69 6.2.5 Indications for improved longevity ............................................................. 70 6.2.6 Cost of composite resin restorations ........................................................... 70

6.3 Discussion ........................................................................................................... 70

6.3.1 Methodological Quality ............................................................................... 70 6.3.2 Clinical Outcomes ....................................................................................... 71 6.3.3 Safety and adverse effects ............................................................................ 71 6.3.4 Implications for outcomes over a lifetime ................................................... 72


6.5 Conclusions......................................................................................................... 73

6.6 Appendix 3: Evidence Tables for composite resin restorations .......................... 74

7 Intra-coronal Bleaching................................................................................................. 78 7.1 Health Technology .............................................................................................. 78

7.2 Results ................................................................................................................. 78

7.2.1 Description of Studies ................................................................................. 78 7.2.2 Clinical Outcomes ....................................................................................... 79 7.2.3 Adverse Effects ............................................................................................ 82 7.2.4 Indications and contra-indications.............................................................. 82 7.2.5 Cost of intra-coronal bleaching ................................................................... 83

7.3 Discussion ........................................................................................................... 83

7.3.1 Methodological Quality ............................................................................... 83 7.3.2 Clinical Outcomes ....................................................................................... 84 7.3.3 Safety and adverse effects ............................................................................ 84 7.3.4 Implications for outcomes over a lifetime ................................................... 84


7.5 Conclusions......................................................................................................... 85

7.6 Appendix 4: Evidence Tables for Intracoronal bleaching ................................... 86

8 Limitations of the review ............................................................................................... 90

9 Recommendations .......................................................................................................... 91

Accident Compensation Corporation Evidence Based Brief Report viii


10 References ................................................................................................................... 93

Appendix 1: Evidence tables for Crowns (go to p 33)......................................................... 97

Appendix 2: Evidence tables for Veneers (go to p 56) ........................................................ 97

Appendix 3: Evidence tables for Composite resin restorations (go to p 74)..................... 97

Appendix 4: Evidence tables for Intracoronal bleaching (go to p 86)............................... 97

Appendix 5. Level of evidence in the SIGN system............................................................. 98

Appendix 6. Studies excluded from this review................................................................... 99

Accident Compensation Corporation Evidence Based Brief Report ix


Accident Compensation Corporation Evidence Based Brief Report x


1 Background ACC funds the placement of approximately 2,600 crowns per annum for clients who have

received an injury to their teeth. Ninety percent of crowns purchased by ACC are on

anterior teeth, and 10% are on posterior teeth. Until March 2007, dentists were not

required to seek prior approval from ACC before placing these crowns, unless they were

for elective treatments.

In November 2006 a random sample of elective treatment requests for dental crown

restorations in ACC clients was reviewed by an independent dental agency to determine

whether crown placement was appropriate and necessary. Of the 59 reviewed, only six, i.e.

10%, were considered necessary and appropriate. The crowns considered inappropriate

and unnecessary fell into five groups:

Group 1: Minimal damage to tooth.

Group 2: Teeth with or needing endodontic treatment, but not indicated for crowns.

A significant portion of tooth structure remains and there is minimal risk

to form and function.

Group 3: Discoloured tooth; indicated for intra-coronal bleaching

Group 4: Tooth should be extracted

Group 5: Dental work does not fit within ACC’s accident/injury legislation, because

the tooth needed restorative treatment before the injury. i.e the dental

complaint was not attributable to the injury.

ACC was alarmed and concerned at finding that 90% of the crowns requested for elective

treatment were inappropriate and unnecessary. While these analyses may be biased

because they were of elective cases, it was an indication that ACC may be funding a

percentage of crowns that should not have been placed in clients teeth. Consequently, in

March 2007 ACC implemented a nationwide interim policy change which required

dentists to seek prior approval from ACC for all crowns before they could be placed on a

clients tooth. Since that time, ACC has seen a sustained 20% reduction in the number of

crowns purchased per annum.

ACC’s primary concern is that clients teeth appear not to be treated conservatively. The

placement of a crown is not considered to be a conservative treatment because it involves

Accident Compensation Corporation Evidence Based Brief Report 11


the irreversible removal of tooth structure which commits the tooth to a path of treatment

that compromises the integrity and life-long health of the tooth. The choice to crown also

eliminates the option to use a range of more conservative dental treatments in the future.

These are all issues of concern because crowns are known to have a limited life, and once

they fail the choices available for re-intervention are very limited. Alternative and variably

more conservative treatments for the restoration of fractured anterior teeth are veneers and

composite resin restoration. For those which are discoloured, intracoronal bleaching can

be used to restore aesthetics.

An evidence based healthcare (EBH) review of crowns, veneers, composite resin

restorations, and intracoronal bleaching was requested to determine what evidence was

present in the dental literature to guide treatment choices. This EBH review is a first step

in the development of ACC guidelines for the restoration of fractured anterior teeth. The

guidelines will be underpinned by this EBH review, but will be developed by a panel of

dentists with a range of clinical experience and expertise. The purpose of the guidelines is

to assist dentists to identify what is the best life-time management of coronal fractures of

anterior teeth; i.e. when a crown should be placed, or when an alternative treatment would

be more appropriate.

2 Objectives To evaluate the clinical outcomes of anterior teeth restored with crowns, veneers, bleach

or composite restorations.

To report any indications/contraindications of crowns, veneers, bleach or composite

restorations with relation to how much tooth structure is remaining after the fracture

injury.

To report any adverse effects associated with crowns, veneers, bleach or composite

restorations.

To provide an EBH report that will inform an expert panel of dentists who will be tasked

with developing guidelines for case selection for crowns, veneers, bleach or composite

restorations which consider the life-time management of injured anterior teeth.



3 Methodology

3.1 Criteria for selecting studies for this review Clinical studies about anterior teeth, of any study type except for individual case studies,

published from 1987 onwards were considered; but there were unique selection criteria for

each intervention. Composite resin studies were limited to traumatised teeth, and bleach

studies were limited to discoloured teeth, whereas crown and veneer studies encompassed

the general population. Shorter follow-up periods were accepted for composite resin and

bleach studies, whereas follow-up periods were limited to 5 and 4 years respectively for

crown and veneer literature. The inclusion criteria for each intervention are detailed and

compared in Table 1. Individual case series were only considered when finding evidence

of adverse effects.

The type of participants included in the review of intra-coronal bleaching requires further

explanation; patients with teeth stained due to fluorosis or tetracycline were excluded.

However, patients with other discolouration, whether caused by trauma or as a result of

endodontic treatment, were included because the aetiology of discolouration can be the

same.

3.2 Criteria for excluding studies from this review Reports about primary teeth, or posterior teeth were excluded from this study. Crown

studies which did not differentiate data on single anterior crowns were excluded. Some

reports did not cite a mean follow-up period; in these cases if the mean was likely to be

less than the inclusion criteria in Table 1, the study was excluded.



Table 1: Summary of Inclusion Criteria for four treatment interventions

Crown Veneer Composite Resin Bleach Types of Study

RCT comparing crowns to other interventions Comparative studies Case series

RCT comparing veneers to other interventions Comparative studies Case series

RCT comparing composite resin restoration to other interventions Comparative studies Case series

RCT comparing bleach to other interventions Comparative studies Case series

Types of Participant

General population with anterior crowns; not limited to trauma population.

General population with veneers; not limited to trauma population

Limited to traumatised teeth

Patients with discoloured anterior tooth as a result of injury, or endodontic treatment

Intervention Single crowns of any type

Porcelain laminate veneers, or direct composite veneers.

Build-up of tooth structure with composite resin, or reattachment of avulsed tooth fragment with composite resin

Intra-coronal bleaching

Outcome measure

Survival rate Failure rate Aesthetics (including gingival margin integrity) Patient satisfaction Adverse effects Implications of a repair/recurrent treatment Dental health outcomes over a lifetime



Tooth colour change Colour stability Failure rate Patient satisfaction Adverse effects Implications of a repair/recurrent treatment Dental health outcomes over a lifetime

Follow-up period

> 5 years > 4 years > 6 months > 6 months

Publication date

From 1987 From 1987 From 1987 From 1987

3.3 Search Strategy and information sources A search of the following literature databases was performed: Cinahl, Cochrane Central

Register of Controlled Trials, Current Contents, embase, Medline, Index New Zealand,

PubMed (RCT/systematic review search only), and the Science Citation index. The search

strategy was aimed at sensitivity rather than precision. The data range was limited to

references in English from 1987 to December 2007 [2008 publications will be

searched/reviewed before publication of final report]. Animal studies were excluded

where possible.

A range of keywords, which described the four interventions, were used to create a master

database of relevant dental literature. The master database was then searched across four



areas to capture studies of different types and focus as follows: RCT’s and systematic

reviews; appropriate or inappropriate utilisation; dental trauma; and safety/adverse effects.

Medline was the major database for dental literature. All other databases yielded much

fewer results and had poor or no indexing for dental information.

Review databases and guidelines compilations were also searched: Cochrane Database of

Systematic reviews, Database of Abstracts of Reviews of Effects, NHS Economic Evaluation

Database, Health Technology Assessment Database, TRIP database, NLH Guidelines Finder

(UK), Scottish Intercollegiate Guidelines Network, National Guideline Clearing House

(US), Guidelines International Network, and the Canadian Medical Association Infobase.

Other sources searched were websites for professional associations, clinical trials, and

international health systems.

3.4 Methods of the review The relevant studies were critically appraised by considering experimental design,

population studied, interventions and outcomes reported. The quality of evidence in each

study included in the review was graded according to the SIGN criteria, summarised in

Appendix 5. The details of included studies were summarised in evidence tables which are

supplied at the end of each intervention section.

3.5 Description of studies The literature search yielded almost 1800 abstracts which were screened for relevant

inclusion criteria. This was reduced to 141 references after the first screen, and full

articles were retrieved. Hand searching of the bibliographies of the retrieved articles

identified additional relevant literature which was also retrieved. Many of the retrieved

articles were commentary style reviews, and after these were excluded 92 references were

selected for critical appraisal for this review. Following critical appraisal, 26 studies were

finally included in this EBH review: 10 about crowns, 8 about veneers, and 4 each about

composite resin restorations and intra-coronal bleaching. Most studies were of

consecutive series of patients, which were usually selected retrospectively. Further detail

about the characteristics of the included studies is provided in the results section for each

intervention review.




Comments from Referee 1: The methodology of the review appears to have been appropriate. While a large number of publications were excluded because they did not meet the inclusion criteria, the findings of this review are unlikely to have been much different if the excluded publications had been included. Comments from Referee 2: The report provides a clear description of the background to the project, the objectives and the methodology which conforms to contemporary best practice in its approach to systematically identifying and reviewing the relevant, valid literature in each of the four areas being considered. The process of identifying reviewing and including information appears to have been carefully applied and to the best of my knowledge, and in the areas where I have taken the time to independently review references, the information that has been presented is an accurate summary of the current literature. The breadth and depth of the review and the process involved makes it unlikely that significant information has remained un-discovered. The fact that the project has focused on English-language literature is unlikely to be significant as most information relevant to practise in New Zealand will either appear directly or indirectly in English. There is no evidence of bias in the report. Significantly: The background to the report, that could be interpreted as being critical of local

practitioners, has been sensitively worded The generally low standard of the available evidence has been appropriately

identified The transparent application of inclusion criteria has helped exclude bias


4 Crowns

4.1 Health Technology An artificial crown is a restoration covering the whole tooth and is intended to repair

damage to individual teeth. Crowns replace tooth structure lost by decay or injury, protect

the part of the tooth that remains, and restore the tooth’s shape and function. Preparation

of a tooth for a crown involves the irreversible removal of a significant amount of tooth

structure. The amount removed is dependent on the type of crown used. For instance a

full gold crown requires a minimum of only 0.5 mm tooth reduction, whereas a porcelain

fused to metal crown requires a minimum of 1.5mm buccal tooth reduction.

There are four classes of crown, classified according to the material they are made of:

Porcelain fused to metal (PFM), all ceramic/porcelain, full gold, and polymer resin crowns

(without metal substructure). This review is primarily concerned with porcelain fused to

metal (PFM) and all ceramic/porcelain crowns.

4.2 Results 4.2.1 Description of Studies There were no RCT’s or comparative studies identified. Forty papers were selected for

critical appraisal, after which 10 studies were included and 30 excluded. All included

studies were case series, having follow-up periods ranging from 5 to 18 years. One study

had an impressive sample size of 19,659, and the other studies had sample sizes ranging

from 17 to 353. [Note that three of the included studies have limited relevance to

crowning practice today because they report on Dicor™ all-ceramic crowns which have

not been manufactured since 1994]. A further nine studies were included in the adverse

effects section.

The primary outcomes reported were survival rate and failure rate. In addition, the cause

and/or incidence of failure is reported in nine papers. None of the studies reported

indications or contraindications with regard to how much tooth structure is remaining

after the fracture injury. However, one study discussed indications relating to age, and

two studies discussed indications relating to root-filled teeth. The characteristics of the

excluded papers are presented in Appendix 6.



4.2.2 Clinical Outcomes The results of 10 studies about single anterior crowns are presented here, and they are

grouped together according to the type of material used in the crown. For a summary of

results refer to Table 2. Many of these studies reported the cause and incidence of crown

failure and this information is also presented below, and summarised in Table 3. Further

details of each study can be found in evidence tables in Appendix 1.

All categories:

Burke et al (2007)1 did a retrospective analysis of a longitudinal sample of dental records

of 47,474 crowns placed in England and Wales over an 11 year period from 1990 to 20021 2.

The life of 19,659 anterior crowns was calculated according to the probability of patients

returning for a re-treatment other than maintenance. These calculations were based on

observed times to re-intervention, and re-intervention was assumed to be associated with

the crown restoration. The survival rate of anterior teeth, without root fillings, was 59% at

10 yrs. If a root filling was placed in the same tooth in the same course of treatment as a

crown the survival rate was reduced to 43%. This study also showed, from whole-of-

mouth data, that all-ceramic crowns showed the least time to re-intervention when

compared with other crown types [note there could be a bias due to tooth position

influencing the types of crown used]; and that patients in the 20 to 29 age band had the

least good outcome in terms of re-intervention. The authors concluded that crowns

should be avoided in younger patients if at all possible, and as resin composite restorations

may be reliably bonded to tooth substance using the acid etch technique there would

appear to be merit in maintaining anterior teeth with such restorations for as long as

possible rather than crowns.

Metal-Ceramic crowns:

Walton (1999)3 4 reported results of a 10 yr longitudinal study, in which 353 crowns were

placed on anterior teeth in a private specialist clinic. The retreatment rate (repair or

failure) was 5.1% and all occurred within the first 5.5 yrs after cementation. The author

reported that non-vital teeth had significantly higher failure and re-treatment rates than

vital teeth, and that crowns on anterior teeth had a significantly greater re-treatment rate

than crowns on posterior teeth.

De Backer et al (2006)5 did a retrospective survival study of 1037 full crowns over 18 years,

76% of which were porcelain fused to gold. The majority of restorations (79.2%) were



post and core crowns and the work was carried out in a University undergraduate clinic.

The number of anterior crowns, and the proportion which were post and core crowns in

the anterior was not stated but the Kaplan Meier survival rate for anterior teeth was

calculated as: 76.1% after 18 years, 83.1% after 12 years and 93.9% after 6 years. The

reasons for failure of anterior teeth were not differentiated from the whole group of teeth.

Porcelain veneer crowns:

Etemadi & Smales (2006)6 did a retrospective case study of 134 anterior teeth treated with

porcelain full veneer crowns, luted with resin cement systems. The failure rate was 12.6%

after 5 years. The reasons for failure were presented, but anterior data could not

differentiated from posterior teeth, see Table 4 for more detail.

All-ceramic crowns: Alumina category

Walter et al (2006)7 did a prospective case series of 61 all-ceramic crowns (Procera

AllCeram). At the 6 year follow up the survival rate was 96.7%. The authors concluded

that the prognosis is very good for Procera AllCeram in anterior restorations provided that

clinical and laboratory instructions are followed.

Odén et al (1998)8 did a prospective study to evaluate the clinical performance of Procera

AllCeram after 5 years. None of the 17 anterior teeth in this study failed due to fracture,

but one tooth required endodontic treatment. The authors concluded that the Procera All

Ceram crown is the all-ceramic restoration of choice for anterior teeth needing a single

crown restoration.

All-ceramic crowns: Glass category

Fradeani & Redemagni (2002)9 did a retrospective analysis of 93 leucite-reinforced glass

ceramic crowns (IPS Empress). At follow-up averaging 7.4 yrs the survival rate was 98.9%.

The authors concluded that leucite-reinforced glass-ceramic crowns showed a low clinical

failure rate and excellent esthetics after up to 11 years.

Erpenstein et al (2000)10 report results from a longitudinal study of 95 ‘Dicor’ glass-

ceramic crowns placed from 1987 until 1994, when manufacture of Dicor ended. The

survival rate at 7 years was 82.7%. The authors concluded that conventionally cemented

Dicor crowns are contra-indicated as a long-term restoration because of high risk of

fracture.




Sjögren et al (1999)11 did a retrospective study of 35 Dicor all-ceramic crowns placed on

anterior teeth between 1987 and 1997. The mean age of incisor crowns was 6.3 yrs, and

for canines it was 7.2 yrs. The failure rate due to fracture was 12%, although half of these

were minor fractures and the crowns were still functioning. The authors concluded that

fracture rates of the Dicor crowns placed on anterior teeth were relatively high and should

be used with caution when the restoration is likely to be subjected to high stress.

Malament & Sokransky (1999)12 did a 14 year prospective study of 422 anterior teeth

restored with Dicor crowns. Ceramic failure was the only factor considered when

reporting outcomes. This study found the following survival rates for acid-etched crowns:

lateral incisors on both arches, 100%; mandibular canine, 84.8%; mandibular central

incisor, 90%; maxillary canine, 91.4%; maxillary central incisor 80.6%. They also showed

that the long-term survival improved significantly when restorations were acid-etched

before luting, and the authors concluded that Dicor restorations present an acceptable risk

when placed in incisor and premolar regions.


Table 2. Summary of crown studies Shaded cells represent studies about Dicor crowns which have not been manufactured since 1994. Reference N

anterior teeth

Crown type Follow-up

Effectiveness (survival/failure)

Comments

Burke et al 20081

19,659 All types 11 years 10 yr survival = 59% without root filling 10 yr survival = 43% with root filling All-ceramic crowns show least time to re-intervention Patients in 20 – 29 age band have least good outcome

Survival = no re-intervention, other than maintenance, required. Represents ‘on the street’ outcomes.

Walton 1997 & 19993

4 353 PFM 10 years 10 yr repair/failure = 5.1%

Non-vital teeth had significantly higher failure and repair rate than vital teeth

Survival = no repair or replacement Private specialist practise.

De Backer et al 20065 (1037 all teeth) N of anterior teeth not stated

PFM 18 years Survival rates for anterior teeth: 6 yr survival = 93.9% 12 yr survival = 83.1% 18 yr survival = 76.1%

Survival = no repair or replacement University undergraduate clinic. 79% of teeth endodontically treated, & received post and core crowns.

Etemadi 20066 134 Porcelain veneer crown

5 years 5 yr failure = 12.6% Survival = no repair or replacement Specialist prosthodontists

Walter et al 20067 61 All ceramic (alumina) (Procera AllCeram)

6 years 6 yr survival = 96.7% Survival = no replacement needed Specialists at University clinic Periodontal disease excluded.

Odén et al 19988 17 All ceramic (alumina) (Procera AllCeram)

5 years No failures due to fracture 1 tooth required endodontic treatment

Survival = no replacement needed Dentist’s expertise level not stated Author developed ProceraAllCeram.

Fradeani & Redemagni 20029

93 All ceramic (glass) (IPS Empress)

7.4 years 7.4 yr survival = 98.9% Survival = no replacement needed Private dental offices Only those with good oral health included (selection bias).

Erpenstein et al 200010 95 All ceramic (glass) (Dicor)

7 years 7 yr survival = 82.7% Dicor crowns contraindicated as a long-term restoration.

Survival = no replacement needed Dentist’s expertise level not stated Periodontal disease excluded.

Sjögren et al 199911 35 All ceramic (glass) (Dicor)

6.3 – 7.2 years

Failure due to fracture = 12% Survival = no intervention A general dental practise; Dentist’s expertise level not stated

Malament & Socransky 199912

422 All ceramic (glass) (Dicor)

14 years Survival of lateral incisors = 100% Survival of mand and max canine = 84.8% & 91.4% Survival of mand and max c incisor = 90% & 80.6%

Survival = no replacement needed One experienced prosthodontist Only those with good oral health included (selection bias).



4.2.3 Incidence and cause of crown failure Seven of the studies discussed above, reported in variable degrees of detail the incidence

and cause of crown failure. Refer to Table 3 for a summary of this data. Causes of failure

were either technical or had a biological origin, and are listed here:

Crown fracture (also chipping and cracking)

Debonding of crown

Caries

Aesthetics (including colour mismatch and margin exposure)

Tooth fracture

Pulpitis/endodontic reasons

Periodontal reasons

Post fracture

With the exception of the study by de Backer et al (2006)5, all studies that reported

incidence figures state that the most common reason for failure of crowns was crown

fracture (responsible for 27 to 40% of failures). Debonding of the crown caused 6 to 15%

of failures; caries caused ~ 24% of failures; aesthetics caused 4-5% of failures. De Backer et

al (2006)5 reported that caries were the major cause of failure (24.3% of failures).



Table 3. Summary of data about the incidence and cause of crown failure. Incidence and Cause of crown failure

Author

N Result/Conclusion Comment

Failure due to Crown fracture

Walter et al 20067 Procera All Ceram

61 anterior teeth Follow-up 6 yrs

3.3% failed due to crown fracture


Fradeani & Redemagni 20029 glass-ceramic crown

93 anterior crowns Average age 7.4 yrs

1.1% failed due to crown fracture


Erpenstein et al 200010 Glass-ceramic (Dicor) crown

76 anterior teeth Average age 7.4 yrs

25% failed due to crown fracture


Sjogren et al 199911 Glass-ceramic (Dicor) crown

35 anterior teeth Average age 6-7yrs

12% failed due to fracture

Incidence and cause of crown failure

Walton 19993 4. Metal-ceramic

353 anterior crowns. 5.1% retreated Age of crown 5-10yrs

Of the retreatments: 50% due to crown or root fracture 25% due to periodontal and caries 15% due to lost retention 4% due to esthetics (margin exposure)


De Backer et al 20065 Metal-ceramic (79% were post and core crowns)

1037 crowned teeth 116 crowns failed 1.8% of the patients accounted for 23.3% of failed crowns; most (74%) of which failed due to biologic reasons. Age of crown up to 18 yrs

Of the irreversible complications: 66.4% due to biologic factors (24.3% caries, 17.2% periodontal, 12.9% fractured tooth, 12% endodontic problems) 39.1% due to technical and patient-related factors (8.7% fracture of porcelain, 6% loss of retention, 4.3% fracture of post, 11.2% needed as abutment for FPD, 1.7% trauma) Of reversible complications: 83% due to technical problems (69% loss of retention, 14% porcelain fracture

Anterior and posterior data can not be differentiated.


Etmadi & Smales 20066 Resin-bonded porcelain veneer crowns

229 crowns 40 failures (17.5%) Age of crown >5 yrs

77.5% of failures occurred in porcelain veneers without metal reinforcement. Of the failures: 40% due to crown fracture 12.5% due to chip 2.5% due to crack 15% due to debonding 5% due to colour mismatch 20% due to pulpitis

Can not differentiate the anterior and posterior data, but 42.5% of failures were in anterior teeth.



4.2.4 Adverse effects Fourteen studies reporting adverse effects of crowns are included in this section, but only

three of these were discussed in the main section of this report. Ten adverse effects were

reported. A limitation of most of these studies is that data for anterior and posterior teeth

was not differentiated and so the statistics presented here do not necessarily portray the

adverse effects (and incidence thereof) for anterior crowns. Furthermore, only three

studies provided a comparison with uncrowned teeth in the same mouth13-15.

The 10 adverse effects reported are:

Altered colour of gingival tissue at the margin of the crown

Gingival recession

Gingival bleeding

Foreign body gingivitis

Peri-radicular periodontitis

Secondary caries

Nickel hypersensitivity related periodontitis

Endodontic failure

Root fracture

Coronal fracture

Refer to Table 4 for further details of the adverse effects and the studies reporting them.



Table 4. Summary of Adverse effects of crowns

Adverse effect

Author [*= full appraisal in text]

N Age of crown

Result/Conclusion Limitation of study

Gingival colour

Sakai et al 198816 (gold crown)

8 teeth

Not stated Discolouration limited to marginal gingival. Colour varied from bluish purple to dark brown or dark gray.

Only 1/8 of the sample teeth were anterior.

Takeda et al 199613 (metal ceramic and resin-veneered)

15 central incisors, plus controls

1-5 yrs Gingivae around many artificial crowns showed a hue shift toward red-purple. Gingival colour differences (b/w crowned & not crowned teeth) were greater in the marginal and papillary areas.

Small sample size.

Gingival Recession

Koke et al 200314 (Porcelain fused to metal)

44 teeth (63% anterior) plus controls

12 months Gingivae tended to recede at crowned teeth during 12 month observation period; Crowned teeth had attachment loss. Originally intra-crevicularly placed crown margins were more or less visible after 12 months.

Anterior teeth not differentiated.

Walton 19993 4* (Metal-ceramic)

353 anterior teeth 5.1% retreated

5-10 yrs 4% of retreatments due to margin exposure.

Gingival Bleeding

Ödman & Andersson 200115 (Procera AllCeram)

87 teeth, 22 anterior; plus controls

5-10.5 yrs Bleeding on probing was recorded for 39% of surfaces around crowned teeth, compared to 27% for control contralateral teeth.

Small numbers; can not differentiate anterior teeth.

Foreign Body Gingivitis

Gordon 200017 (porcelain fused to metal)

1 tooth 2 yrs Persistent gingival inflammation associated with porcelain fused to metal crown was diagnosed as foreign-body gingivitis. Analysis of fragments of crystalline foreign material revealed statistically significant quantities of aluminium, silicon, magnesium, manganese and zirconium.

A case study, briefly reported.

Periodontal problems and caries

Saunders & Saunders 199818 (Type of crown unknown)

802 crowns 57% vital 43% endodontic

unknown 19% of vital preparations had signs of periradicular disease. 58% of teeth with endodontic treatment had signs of peri radicular radiolucency.

Anterior teeth not differentiated.



5-10 yrs 25% of retreatments were due to periodontal problems and caries.




Adverse effect

Author [*= full appraisal in text]

N Age of crown

Result/Conclusion Limitation of study

Periodontal problems and caries

De Backer et al 2006*5 (Metal-ceramic)

1037 crowns 116 failures

Up to 18 yrs

24.3% failures due to caries. 17.2% failures due to periodontal problems.

Anterior and posterior data cannot be differentiated.

Zoellner et al 200219 (Crown material unknown)

365 teeth

unknown 9.3% of single crowns failed due to secondary caries. There was an inclusion bias for patients with obvious past and/or present secondary caries lesion. Anterior and posterior data can’t be separated.

Wilson et al 200320 (72% porcelain fused to metal)

712 crown replacements

not stated 15% of the crown replacements were due to caries. Anterior and posterior data can’t be separated. However 72% crown replacements were on anterior teeth.

Nickel hypersensitivity related periodontitis

Bruce & Hall 199521 (Porcelain fused to metal)

1 case

unknown Periodontitis correlated with location of new crowns containing nickel.

One case study.

Endodontic failure

Jackson et al 199222 (Crown material not stated)

437 vital teeth with fixed prostheses

2-6 yrs 1.8% of vital anterior teeth subsequently had or now needed root canal therapy.

Only 11% response to recall request; Can’t differentiate the single crown and fixed partial denture data in the anterior teeth data.

Cheung 199123 (Porcelain crown)

34 anterior crowns

2.8 yrs 3% of crowns had endodontic failure. Small sample size. Selection bias: only 38% of selected patients followed through.

Wilson et al 200320 (72% porcelain fused to metal)

712 crown replacements

not stated 3% of the crown replacements were due to endodontic failure.

Anterior and posterior data can’t be separated. However 72% crown replacements were on anterior teeth.



Up to 18 yrs 12% of failures due to endodontic problems. Anterior and posterior data cannot be differentiated.

Etmadi & Smales 2006*6 (Porcelain veneer crowns)


>5 yrs 20% of failures due to pulpitis. Can’t differentiate the anterior and posterior data; but 42.5% of failures were in anterior teeth.

Tooth and Root fracture



5-10 yrs 50% of retreatments due to crown or root fracture.



Up to 18 yrs 12.9% failures due to fractured tooth. Anterior and posterior data cannot be differentiated.


4.2.5 Patient Selection Criteria: Risk Factors for longevity Only two risk factors for longevity were identified in the included studies. However, it

should be noted that both of these findings applied to whole of mouth data, rather than

anterior teeth only:

Patients in the 20-29 yr age bracket: Burke et al (2008)1 showed that crowns

placed in 20-29 yr olds had a poorer outcome (p<0.0001) than patients in the 30-

39 yr and 40-49 yr age brackets1. Patients in the 70-79 yr age bracket had the

poorest outcomes of all.

Non-vital teeth: Both Burke et al (2008)1 and Walton (1999)4 showed that non-vital

teeth had poorer outcomes than vital teeth. The study of the England and Wales

general dental service showed that when a root filling was placed in the same

course of treatment as a crown, the survival rate was reduced from 59% to 43% at

10 yrs (p<0.0001)1. In Walton’s (1999) 10 yr longitudinal study of 688 crowns,

non-vital teeth had a significantly poorer failure outcome (5%) compared to vital

teeth (1%) (p<0.05)4.

There were no studies that reported indications or contraindications for crowns in relation

to how much tooth structure is remaining.

4.2.6 Cost The median price in New Zealand of an all-ceramic crown is $1019, and for a porcelain

fused to metal crown it is $973. ACC’s contribution to the cost of a crown is $800 (plus

$90 for a temporary crown) for an all-ceramic crown and $771 (plus $90 for a temporary

crown) for a porcelain fused to metal crown.

4.3 Discussion 4.3.1 Methodological Quality Study design: The methodological quality of the crown studies is low by evidence based

healthcare standards because they were all case series, and only 3 of the 10 studies were

designed prospectively. None of the studies is directly comparable because of variations in

almost every aspect of the studies: patient selection criteria, number of patients, follow-up

period, crown type, clinical setting, measurement and reporting of outcomes.



Sample size and statistical analysis: Other than the large sample size of the English and

Wales general dental service (19,659 patients)1 the sample size for studies of anterior

crowns ranged from 17 to 422. Five studies had <100 participants and consequently have

less statistical power. The Burke et al (2008)1 study utilised sophisticated statistics in the

analysis of data and had strong statistical power due to the large sample size, reporting p

values of 0.00011. All studies except for one8 calculated survival rate using Kaplan-Meier

statistics (or similar). However, three of the studies reported survival rate for the whole

mouth, and so survival statistics for anterior teeth were not available from these studies4 6 11.

Some studies also used other statistical tests such as the chi squared test and the Fisher test.

The study by Odén et al (1998)8 did not apply any statistical test or analysis other than

calculating percentages.

Intervention: The exact crown intervention was variable between studies due to different

choices of materials, luting agents or different methods of tooth preparation. One study

included crowns of all types1, two studies used porcelain fused to metal crowns4 5, six

studies used all-ceramic crowns7-12, and one study used porcelain veneer crowns6. The

clinical setting in which the interventions were placed varied from general dental practise,

to private specialist practise, and university dental clinics. The clinical setting is a relevant

consideration when interpreting study outcomes, because confounding factors may

include different technical skills of the practitioners, and some self-selection of patients.

These variations limit the ability to compare studies directly.

Study population, inclusion and exclusion criteria: The study population for crown

studies was not restricted to patients with fractured teeth; it was not possible to isolate

trauma-only patients from the study statistics, and indeed none of the studies reported

solely on a trauma population. The reasons for study participants receiving crowns varied

from study to study. Common reasons were trauma, aesthetic considerations (including

discolouration), to restore structural integrity (including those that had extensive loss of

crown substance due to caries), or to replace a failed crown or other restoration. All ten

studies included both anterior and posterior crowns, however only the data for anterior

crowns was presented in this EBH report. The endodontic status of participants teeth was

mentioned in only two papers5 9 and the statistics related to the whole mouth, rather than

anterior teeth only.

Patient selection criteria, and inclusion and exclusion criteria were not fully reported in

some studies. With the exception of a randomly selected participant sample in the Burke



et al (2008)1 study, most studies selected consecutive patients treated between particular

dates. Three studies set no particular exclusion criteria1 4 10, however 3 studies excluded

patients with poor oral health7 9 12, and so these studies may have lower external validity

due to this selection bias. Three studies excluded patients who dropped out during the

follow-up period5 8 11.

Follow-up and study period: Included studies had mean follow-up periods of at least 5

years. In studies where the Kaplan-Meier survival rate is calculated, the follow-up period

reported is the maximum follow-up period calculated for that particular study; it is not the

mean. Six studies had short to medium term follow-up periods (5-7 yrs), and three had

medium to long term follow-up periods (7-15yrs). Only one study had follow-up data

beyond 15 yrs5. Given that crowns are commonly perceived to be permanent long-term

restorations, ideally one would like to see follow-up periods of >20 yrs. One of the main

reasons for excluding crown studies from this report was short follow-up periods.

Outcome measures: The primary outcome measure for crowns was survival/failure rate

over a certain period. However, there was variability in the way survival or failure was

defined (e.g. whether ‘failure’ includes repairable failures or not), and which criteria were

assessed when determining failure or survival. This variation limits the ability to compare

studies directly. Only two studies analysed patient factors which may influence the

survival of crowns1 4.

4.3.2 Clinical Outcomes The primary clinical outcome reported for crowns was survival/failure rate. The survival

rate of crowns in England and Wales over 10 years ranged from 43% to 59% depending on

whether the tooth had a root filling1. Of the crown studies included in this report, this

study has the highest external validity because data was obtained from the General Dental

Service, and furthermore the sample size was 19,659 anterior teeth, giving the study

exceptional statistical power. It is unknown whether these ‘on the street’ figures would be

mirrored in New Zealand, but it is not unreasonable to expect that this would be the case.

Comment from Referee 1 I would suggest caution in comparing dental treatment decisions in the NHS in the UK with what occurs in New Zealand because the NHS has provided publicly funded dentistry whereas NZ dentistry is largely privately funded. Publicly funded dentistry can sometimes impose treatment guidelines and funding on dentists that effect some treatment decisions that may not occur in privately funded dentistry. Comment from Referee 2



The statement (pg 28) that the UK study “.. has the highest external validity because the data was obtained from the General Dental Service .. (and that) … it is unknown whether these “on the street” figures would be mirrored in New Zealand, but it is not unreasonable to expect that they this would be the case” is probably appropriate. In the end the relative success of different treatment strategies is probably more important than the absolute success rate and these are appropriately derived from studies with very large sample sizes.

The other studies have less external validity, but nevertheless they provide useful data on

specific types of crowns, placed within specific clinical settings. The failure rates reported

in these studies are considerably lower than the failure rate reported for the England and

Wales dental service. The failure rate for PFM crowns varied between the two PFM

studies included in this report. The 10 year repair/failure rate at a private specialist

practise was 5.1%4, whereas the 12 year failure rate at a university undergraduate clinic

was more than three times greater at 16.9%5. The failure rate had increased to 23.9% by 18

years follow-up5. A possible confounding factor in this study by De Backer et al (2006)5 is

that 79% of the teeth were endodontically treated, and received post and core crowns.

Note that the definition of failure in the studies by Burke et al (2008)1, Walton (1999)4 and

De Backer et al (2006)5 is a crown needing replacement or repair.

The three reports about Dicor™ all-ceramic crowns, and the outcome data held therein

have limited relevance to considerations of modern dentistry in New Zealand because they

have not been manufactured since 1994. However, the relatively high number of failures

reported in these studies could provide a benchmark when deciding whether a rate of

failure is unacceptable or not. Overall, the high failure rates led most authors to conclude

that Dicor crowns are contra-indicated as a long-term restoration on anterior teeth.

Failure of Dicor all-ceramic crowns ranged from 12 - 17% at around 7 years follow-up 10 11

but were better in Malament’s study which reported 14 year failure data for mandibular

canines and maxillary central incisors of 15.2% and 19.4% respectively12. There did seem

to be a tooth position effect on survival outcomes because there were no failures on lateral

canines of either arch after 14 years12.

Other brands of all-ceramic crowns (Procera AllCeram, IPS Empress) had lower failure

rates (1-6%), as reported at 5-7 years follow-up7-9. However, the definition of failure in

these studies was less stringent than the Burke et al (2008), Walton (1999) and De Backer

(2006) studies because it only included crowns requiring replacement. A study of a

porcelain veneer crown reported a comparatively high failure rate of 12.6% after 5 years6.

The main causes of crown failure are crown fracture, debonding of the crown, and caries.



4.3.3 Safety and adverse effects In general, the adverse effects were reported in studies of both anterior and posterior teeth.

However, it is assumed that anterior teeth are as susceptible to these adverse effects as

posterior teeth.

Whilst gingival colouration and gingival recession seemed to impact mostly on aesthetics,

the other reported adverse effects (periodontal problems, caries, endodontic failure, and

tooth and root fracture) are somewhat more serious because they cause crown failures.

4.4 Summary of Evidence Evidence from the three best studies1 4 5 shows that there is a large variation in the survival

rate of crowns (43-95%) over 10-12 yrs. The study with the highest external validity (i.e.

most relevant to New Zealand’s dental service) reported survival rates of 43-59%1.

Survival in these three studies was defined as a crown that does not require either

replacement or repair. It is not possible to conclude with confidence why there is such

large variation because there are confounding factors in all three studies. However one can

speculate based on the study information provided:

Walton (1999)4 provided reasonable evidence to suggest that the survival of PFM

crowns in the medium term (10 yrs) is very good (95% survival). This outcome

may be comparatively better because the crowns were placed in a private specialist

practise (95%)4.

De Backer et al (2006)5 provided reasonable evidence that the medium term (12 yr)

survival rate of PFM crowns is 83% and lower than Walton (1999)4 would suggest.

This poorer outcome may be because the crowns were placed in a university

undergraduate clinic, or it may be due to patient risk-factors, such as 79% of the

teeth being non-vital and endodontically treated.

Burke et al (2008)1 provided good, externally valid evidence, supported with strong

statistical power, that the medium term (11 yr) survival rate of crowns in a general

population is poor (43-59% survival) when crowns are placed in a general dental

service1. Whether this is a truly accurate representation of ‘on the street’ outcomes

depends on the validity of the researchers’ assumption that re-interventions were

associated with the crown restoration.




Comments from Referee 2: The report appropriately recognizes the complexities of comparing outcomes between general practice, specialist practice and university clinics. Comparing data from Burke (2008) and Walton (1999) is difficult (page 18). The Burke data is for publicly-funded services provide by general practitioners. In comparison Dr Walton is a former president of the International College of Prosthdontists with an international reputation for excellence in fixed prosthodontics.

There is evidence from three lesser quality studies7 8 24 that the short term (5-7 yrs) failure

rate (i.e. replacement) of ceramic crowns is very low (1-4%). These studies are of lesser

quality because of low participant numbers, a selection bias towards patients with good

oral health, or a commercial-interest bias. These studies have low external validity.

There is reasonable evidence from a single study that the short term (5 yr) survival rate of

porcelain veneer crowns is comparatively poor (12.6% repaired or replaced)6.

There is reasonable evidence from two studies that a risk factor for the longevity of crowns

is placement on non-vital teeth1 4; and reasonable evidence from one study that being in the

age bracket 20-29 yrs is a risk factor for longevity of crowns1.

There is reasonable evidence from 7 studies that failure of crowns is caused either by a

technical failure of the crown itself (fracture or debonding) or by adverse effects on oral

biology such as periodontal problems, secondary caries, endodontic failure, and tooth and

root fracture.

4.5 Conclusions The outcome measures are dominated by survival/failure rates, and these data indicate that

crowns applied by appropriate specialists can be highly successful in the medium term

(10yrs)4. However, in a general practise setting the survival rates appear to be poor in the

medium term (43-59%)1.

There is insufficient evidence to establish guideline-quality patient selection criteria for

placement of crowns on anterior teeth. However, the data did identify two risk factors:

1. Non-vital teeth are a risk factor for reduced longevity of crowns

2. People in the 20-29 yr age bracket are at risk of reduced longevity of crowns.


4.6 Appendix 1: Evidence Tables for Crowns Evidence Based Healthcare Table Dental Crowns Reference: Burke & Lucarotti 20081 Bibliographic Number: Design Description Participants Intervention Outcomes

Description: The data set included patients:

a) whose date of acceptance was after Sept 1990 and before January 2002, (i.e. Oct 1991 to Dec 2001).

b) Whose birthdays were included within a set of randomly selected dates, one of which was chosen in each year.

c) Whose treatment was on or after their 18th birthday

Outcome Measures: Life of a restoration = interval between successive interventions. This interval was calculated using probabilities, as described in 2. Survival rate = % expected to survive after a given period, according to Kaplan-Meier method using ‘life of a restoration’ data. Definition of Re-intervention: the treatment, other than maintenance, that took place at the next intervention recorded for the crowned tooth. The re-intervention is considered to be associated with the original restoration, because crowns generally cover most of the surface of the tooth; so likelihood of there being no causal connection between original restoration and the re-intervention is low.

No. in Group: 19,659 anterior teeth Age: most frequently in 30 to 49 age group.

Inclusions: Patients >18 yrs at time of crown treatment

Exclusions:

Results: Canine teeth have the poorest survival rate to next intervention (48% at 10 yrs), followed by incisor teeth (55% for lateral incisor and 61% for central incisor) (p<0.0001). Survival rate of anterior teeth is reduced from 59% to 43% at 10 years if a root filling is placed in the same tooth in the same course of treatment as a crown (p<0.0001). All-ceramic crowns show the least time to re-intervention when compared with other crown types (p<0.0001). Patients in the 20 to 29 age band have the poorest outcome in terms of time to re-intervention (p<0.0001), (other than the 70-79 age grouo).

A retrospective analysis of a longitudinal sample of dental records of 47,474 crowns placed in England and Wales over an 11 year period from 1990 to 2002. Dates of treatment for each tooth and date of next intervention for that tooth were consulted to calculate the time to re-intervention of teeth. The whole set of analyses was repeated on a second and non-overlapping random sample selected in the same way. Analysis was done using right-censored data. i.e. the end time of a restoration is not exactly known but is placed after a specified time, but without further limit. The method involved first estimating the probability that a patient will eventually return for re-treatment by analysing the observed patterns of re-attendance. This estimated probability of re-attendance can then be used to modify the standard Kaplan-Meier procedure to produce realistic estimates of the hazard of re-intervention.

Selection Notes: See paper for more details of methodological theory.

Placement of crowns on anterior teeth. 80% of crowns were Metal-ceramic bonded crowns. Maintenance is not considered to be a re-intervention.

Methodological Score: 3



Evidence Based Healthcare Table Dental Crowns Reference: Walton 19993 4 Bibliographic Number: Design Description

Participants Intervention Outcomes

Description: Documented reasons for seeking crowns were aesthetic considerations, structural integrity and previous crown failure. 688 crowns in the whole study

Outcome Measures: Retreatment = repair and/or failure. (where failure is when the crown is lost, or the crown had been recemented more than twice) Success = no evidence of retreatment other than maintenance procedures. Follow-up period was from 5 to 10 yrs

No. in Group: 353 anterior crowns Age: 81% of patients were aged 30 to 59 yrs

Inclusions: Patients who were treated with crowns from Jan 1983 to Dec 1992.

Exclusions: Patients whose crowns were only 1 – 5 yrs old; these patients were not included in the statistical analysis.

Results: Retreatment = 5.1%. Occurred within the first 5.5 yrs after cementation (range 0.9 – 5.5 yrs). Mean service age was 3.3 yrs Major cause of retreatment: approx 50% were coronoradicular and root fractures Other biologic causes were periodontal and caries (approx 25%). Mechanical – lost retention (approx 15%) Esthetic – margin exposure (approx 4%) Anterior non-vital teeth had significantly higher failure and retreatment rates than anterior vital teeth (p<0.05). Crowns on anterior teeth had significantly greater re-treatment rate than crowns on posterior teeth.

A 10 yr longitudinal study of single-unit metal-ceramic crowns. Not stated whether the study was designed prospectively or retrospectively.

Selection Notes: Only data for anterior teeth was included in this EBH table. Data posterior teeth were excluded.

Metal-ceramic crowns placed on anterior teeth between Jan 1983 and Dec 1992, in a private specialist practise. Procedures were standardised as much as possible.




Evidence Based Healthcare Table Dental Crowns Reference: De Backer et al 20065 Bibliographic Number: Design Description


Description: 1312 full crowns placed over 18 yrs from 1974 to 1992. Records available for 456 patients, 1037 crowns. Root canal-treated teeth with a post and core crown represented 79.2% of the study group. Patients invited to have regular maintenance program every 6 months. Reasons for full crown prep were: Extensive loss of crown substance because of caries (66%) Replacement of existing restoration (12.2%) Trauma (7.7%) Endodontic problems (6.3%) Esthetic reasons (5.4%).

Outcome Measures: Failures: Irreversible complication: loss of full crown and/or tooth Reversible complication: full crown intact after conservative treatment Biologic or technical failures differentiated. Biologic failure = caries, periodontal problems, fracture of the abutment tooth, endodontic problems. Kaplan Meier survival rate calculated

No. in Group: not differentiated for anterior teeth Mean Age:

Inclusions: Those patients which full records available

Exclusions: Patients who dropped out. Reasons for drop out were: patients chose a private practitioner for maintenance, moved to another city, could not be traced, or died during follow-up period.

Results: The Kaplan-Meier survival rate for anterior teeth was calculated at 18, 12 and 6 yrs as follows: 18 yrs: 76.1% 12 yrs: 83.1% 6 yrs: 93.9%

Retrospective survival study of full crowns with or without posts

Selection Notes:

Crowns were placed in undergraduate university clinic, Belgium. Patients were invited to participate in a regular supportive maintenance programme every 6 months. Crowns either cast gold (24%) or porcelain fused to gold (76%).




Evidence Based Healthcare Table Dental Crowns Reference: Etemadi & Smalesl 20066 Bibliographic Number: Design Description


Description: Older adolescent and adult patients who had RBPVCs placed during 1988-1995 on anterior and posterior teeth. Restorations placed due to discoloured, fractured or worn teeth/restorations, and for altering form of tooth as part of orthodontic therapy.

Outcome Measures: Failure of crown: defined by authors as crowns requiring repair, monitoring or replacement. Follow-up: at least 5 years

No. in Group: 134 anterior teeth Mean Age: not stated

Inclusions: Older adolescent and adult patients who had RBPVCs placed during 1988-1995 on anterior and posterior teeth

Exclusions: Restorations without opposing occlusal tooth contacts

Results: 17/134 anterior crowns failed = 12.6% failure Failure-mode data was not differentiated for anterior and posterior teeth. For the whole group of 229 restorations, failure modes were: Bulk fracture of porcelain Chip fracture of porcelain Crack fracture of porcelain Debonding Colour mismatch Pulpitis (tooth sensitivity)

A retrospective case study of dental records to compare long-term failure rates and modes for all-ceramic veneer crowns (resin-bonded sintered feldspathic porcelain veneer crowns, RBPVCs) either with or without metal reinforcement (i.e. porcelain fused to metal).

Selection Notes: Data on posterior teeth were excluded for this EBH summary wherever possible.

Placement of porcelain veneer crowns using dual-cured resin cement systems 17 crowns had metal reinforcement 117crowns had no metal reinforcement Restorations done by two specialist prosthodontists.




Evidence Based Healthcare Table Dental Crowns Reference: Walter et al 20067 Bibliographic Number: Design Description


Description: Patients who had all-ceramic crowns with alumina cores (Procera Alumina AllCeram crowns) placed on anterior or posterior teeth in 1997 and 1998.

Outcome Measures: Failure = replacement of crown Survival = no removal Follow-up period was 6 years.


Inclusions: Patients in need of crown treatment and demanding superior aesthetics.

Exclusions: Active periodontitis, current use of removable dentures, and ongoing orthodontic treatment.

Results: 2/61 crown fractures; had to be removed. Survival rate = 96.7% +/- 2.3% Minor fractures within dental porcelain were found in 4 additional cases (anterior v’s posterior location not differentiated). These defects were smoothened and polished.

A prospective case study of patients treated with Procera Alumina AllCeram crowns, followed for 6 years.

Selection Notes: Data for posterior teeth not included in this EBH table where ever possible.

Placement of Procera Alumina AllCeram crowns on anterior teeth Restorations done by 3 specially trained clinicians at a Dental school




Evidence Based Healthcare Table Dental Crowns Reference: Odén et al 19988 Bibliographic Number: Design Description


Description: The experimental population consisted of 58 patients who need crown therapy for a variety of reasons. They were selected from consecutive patients of 4 general practitioners.

Outcome Measures: Failure = fracture of crown Follow-up period > 5 yrs No statistical tests were applied in analysis of outcomes.

No. in Group: 17 anterior teeth (out of group of 97 crowns) Mean Age:

Inclusions: Patients who needed crown therapy for a variety of reasons.

Exclusions: Two patients, (3 crowns) lost to recall.

Results: 0% failure Complication: 1 incisor showed clinical sign of pulpal inflammation and was endodontically treated through the crown 14 days after cementation

A prospective study to evaluate clinical performance of Procera AllCeram crowns after 5 yrs of service. Patients were selected until 100 crowns (posterior or anterior) were placed.

Selection Notes:

Placement of Procera AllCeram crowns. Preparation was 0.6mm deep. Most crowns of whole group (97) were luted with conventional luting agents (zinc phosphate cement, or glass ionomer cement). Only 4/97 luted with dual-cure resin cement.

Methodological Score: 3 Bias risk: contributing author was a Manager at Procera



Evidence Based Healthcare Table Dental Crowns Reference: Fradeani & Redemagni 20029 Bibliographic Number: Design Description


Description: Patients needed crown therapy for a variety of reasons. The study population was selected from consecutive patients at the authors’ offices. A total of 125 crowns were included in the study; 70 were placed on endodontically treated, 55 were placed on vital teeth. Only data for anterior teeth is considered in this EBH table

Outcome Measures: Failure = crown needed replacement Average follow-up = 7.4 yrs; ranged from 4 to 11 years. Kaplan Meier statistics were used.

No. in Group: 93 anterior crowns in 54 patients Mean Age: 41 yrs female, 40 yrs male

Inclusions: Patients who received all-ceramic IPS Empress crowns between May 1990 and December 1996, a 6 year period. Only those with good oral health were included in the analysis.

Exclusions: 45/170 (26%) crowns excluded from study due to patients lost to follow-up or who died. Patients with severe parafunction, periodontitis, serious gingival inflammation, poor oral hygiene or high caries rates.

Results: Failure rate of 1.1%. (one crown failed due to fracture 6 yrs after placement) Survival probability at 11 years is 98.9%

A retrospective evaluation of leucite-reinforced glass-ceramic crowns placed on anterior and posterior teeth.

Selection Notes:

Crown placement on anterior teeth. 1.2-1.5 mm preparations done. Dual-polymerizing resin composite cement was used to lute most restorations. Gingival margins located either at gingival crest, or slightly in the sulcus. Work performed by two clinicians.

Methodological Score: 3 Bias risk: Study may not reflect a true ‘general population’ because only those with good oral health were included for analysis.



Evidence Based Healthcare Table Dental Crowns Reference: Erpenstein et al 200010 Bibliographic Number: Design Description


Description: Patients were periodontally healthy.

Outcome Measures: Failure = fracture of crown (loss of the fractured segment) Survival rate = not fractured; Calculated by Kaplan-Meier method. Incomplete fracture = a crack in the cement. Follow-up was up to 11 years. Mean years at risk was 7.4 yrs.

No. in Group: 95 anterior crowns Mean Age: 40.8 yrs (+/- 9.8 yrs)

Inclusions: Periodontally healthy patients wanting anterior teeth crowned

Exclusions: For EBH Table: Anterior crowns using galvano-ceramics excluded because follow-up less than 5 yrs. Posterior teeth excluded.

Results: 19/95 (20%) anterior crowns failed due to crown fracture Survival rate at 7 years = 82.7% (+/- 8.1)

A longitudinal clinical study of performance of two types of crowns, on anterior or posterior teeth. Types of crown studied were glass-ceramic (Dicor) and galvano-ceramic (Auvo Galvano). Not stated whether prospective or retrospective study design.

Selection Notes: For this EBH table, only anterior teeth treated with glass ceramic crowns were selected for inclusion.

Placement of Glass-ceramic crowns (Dicor) on anterior teeth from April 1987 – August 1994. (NOTE: Dicor manufacture ended in 1994 due to large number of failures). Conventional cement was used (zinc phosphate). Most treatments (until year 10 of study) were done by one dentist.




Evidence Based Healthcare Table Dental Crowns Reference: Sjögren et al 199911 Bibliographic Number: Design Description


Description: 63 Patients treated with Dicor all-ceramic crowns between 1987 and 1997 were invited to participate in the study, and were given an appointment to have their crowns independently examined. Both posterior and anterior crowns were examined, but only anterior teeth considered in this EBH table.

Outcome Measures: Failure: not defined Mean age of incisor crowns was 6.3 +/- 1.8 yrs; range 1.6 – 9.2 years. Mean age of canine crowns was 7.2 +/- 2.2;range 5.6- 8.8

No. in Group: 35 anterior crowns (98 crowns in total group) Mean Age: women 56.5 yrs, men 52.4 yrs for whole group

Inclusions: Not stated

Exclusions: Those who didn’t keep their assessment appointment; those who were ill.

Results: 4/35 (12%) anterior crowns failed due to fracture. Two of these were minor fractures and were crowns still functioning.

A retrospective study of patients treated with Dicor all-ceramic crowns between 1987 and 1997.

Selection Notes: Data for posterior teeth was ignored for purposes of this EBH table.

Anterior teeth treated with Dicor all-ceramic crowns Most crowns placed at level of gingival margin All work done by one dentist from a general practise. Two evaluators examined the crowns Luting method: not defined specifically for anterior teeth, but of whole group of 98 crowns, 54 glass ionomer cement, 30 with zinc phosphate, 14 with composite cement.





Evidence Based Healthcare Table Dental Crowns Reference: Malament & Socransky 199912 Bibliographic Number: Design Description


Description: Patients aged from 17 to 91 yrs, recruited in a clinical private practice. Patients offered choice of 3 materials, but told that Dicor offered potentially improved esthetic results, and had some fracture potential compared with feldspathic ceramic.

Outcome Measures: Measured failure of ceramic only; not reporting on other causes of crown failure, such as caries, endodontic failure etc. Failure = the crown has a fractured ceramic piece that necessitated a replacement crown. [chips <1mm were reshaped and polished]. Probability of survival was calculated using Kaplan Meier method.

No. in Group: 1444 crowns total; 422 anterior teeth crowned Mean Age: not stated

Inclusions: Patients had excellent oral hygiene, minimal periodontal inflammation. Tooth preparation length was adequate; teeth exhibited minimal mobility.

Exclusions: Patients with poor oral hygiene, uncontrolled periodontal inflammation or if they preferred gold or metal-ceramic restorations.

Results: The probability of survival of acid-etched crowns at 14 yrs of a: Mandibular canine = 84.8% Mandibular lateral incisor = 100% Mandibular central incisor = 90% Maxillary canine = 91.4% Maxillary lateral incisor = 100% Maxillary central incisor = 80.6% Concluded that Dicor restorations present an acceptable risk when placed in incisor and premolar regions [These rates are better than for molars; max 1st molar was 48.3%; mandibular 2nd molar was 48.8%; mand 1st molar 74.1%] Long term survival improved significantly when restorations were acid-etched before luting.

A prospective study of Dicor glass-ceramic crown survival

Selection Notes:

Placement of Dicor glass ceramic single unit crowns on teeth. Followup period was for 14 yrs

Methodological Score: 3 Bias risk: study may not reflect a true general population because only those with good oral health were included in study


5 Veneers

5.1 Health Technology Veneers are restorations that cover the labial surface of a tooth and are used to improve the

colour, form and/or position of anterior teeth. Veneers are comprised of either a thin

porcelain laminate or of composite resin. The popularity of using porcelain veneers to

restore the aesthetics of anterior teeth increased in the early 1980s when an acid-etching

procedure was introduced that substantially improved the long-term retention of this type

of veneer25 26. Retention is achieved by micromechanical retention of the porcelain to the

tooth via a resin composite luting material. Irreversible enamel reduction of at least 0.5

mm is required to accommodate the minimal 0.5mm thickness of porcelain, and in order

to improve the bonding of the porcelain to the tooth.

5.2 Results 5.2.1 Description of studies There were no RCT’s or comparative studies identified. Of the 20 studies selected for

critical appraisal, eight studies were included and 12 were excluded. All included studies

were case series, having follow-up periods ranging from 5 to 12 years. One study had a

substantial sample size of 2,562, whilst the other studies had small sample sizes ranging

from 36 to 191. One additional study is cited in the adverse effects section. The quality of

reporting varied substantially.

The primary outcomes reported were survival/failure rate, or clinical acceptability/

unacceptability, although the definition of failure was not consistent across the studies.

Marginal adaptation, marginal discolouration, caries recurrence and patient satisfaction

were criteria commonly assessed when determining whether a veneer failed. Only one

study reported a contraindication with regard to how much tooth structure is remaining

after a fracture injury. One study reported the consequence of retreatment, and of high

caries activity, and also presented age contraindications. Two studies reported

contraindications related to the presence of composite restorations at the veneer margin.

The characteristics of the excluded papers are presented in Appendix 6.



5.2.2 Clinical Outcomes The results of 8 studies about veneers are presented here. For a summary of results refer to

Table 5. Further details of each study can be found in evidence tables in Appendix 2.

Burke and Lucarotti (2008)27 did a retrospective analysis of a longitudinal sample of dental

records of 2,562 porcelain veneers placed on anterior maxilla teeth in England and Wales

over an 11 year period from 1991 to 2002. The life of these veneers was calculated

according to the probability of patients returning for a re-intervention, based on observed

times to re-intervention. Modified Kaplan-Meier statistics were used to determine a

survival rate of 53% at 10 years, i.e. 53% of the porcelain veneers were present without re-

intervention. An analysis of the treatments provided at re-intervention of a veneered tooth

illustrated that in the first year ~10% were recemented, ~40% were replaced with another

veneer, ~10-20% were replaced with a crown, and ~20-30% received direct placement

restoration. About 2% were extracted. Changes in re-treatment patterns were observed as

time since placement of the original veneer progressed; the types and frequencies of

retreatments were observed as follows: proportion treated with a replacement veneer

decreased to ~20%, and the proportion of crown treatments became more variable (~10-

50%), extractions became more predominant (~10%), as did the proportion of teeth

treated via direct placement restoration (>40%). When patient factors were considered it

was found that older patients (>60 years) and younger patients (<30 years) demonstrated

poorer survival of porcelain veneers (p=0.003), as did those with high caries activity (as

evidenced by high annual treatment costs and/or frequent attendances) (p<0.001). When

dentist factors were analysed the results demonstrated that the age, year of training and

experience of a dentist had no influence on the survival of porcelain veneers.

Fradeani et al (2005)28 did a retrospective study of 182 anterior teeth restored, for various

reasons, with porcelain laminate veneers fabricated by both a pressed ceramic technique

(IPS Empress) and a refractory die technique (feldspathic porcelain, Vitadur Alpha, Vita).

The work was done by two dentists between 1991 and 2002. The clinical failure rate was

5.6%, and the 12 yr survival rate was 94.4%. Aesthetics, assessed according to CDA/Ryge

criteria, were satisfactory. Whilst marginal discolouration was considered acceptable it

recorded the lowest proportion of ‘A’ ratings.



Smales & Etemadi (2004)29 did a retrospective study of porcelain veneer restorations of

110 anterior teeth with various indications for treatment. The work was done by two

specialist prosthodontists between 1989 and 1993. Forty two percent of veneers had

incisal coverage. The cumulative survival rate over 7 years was 95.8% in veneers with

incisal coverage and 85.5% in veneers without incisal coverage. This difference was not

statistically different.

Peumans et al (2004)30 did a prospective clinical trial of 87 porcelain veneers in anterior

teeth, plus first premolars, and reported a 5 and 10 yr follow-up. The work was done by

one dentist in 1990 and 1991. The overall clinical acceptance decreased substantially

between the 5 and 10 yrs follow-up from 92% to 64%. Patient satisfaction decreased

between the 5 and 10 yr follow-up (from 80% to 59%), as did marginal integrity. Large

marginal defects were found in 20% of restorations and were especially noticed at locations

where the veneer ended in an existing composite filling. After 5 yrs 14% of veneers had

excellent marginal adaptation, and by 10 yrs this reduced to just 4%. Increases were

observed in the fracture rate (from 4% at 5 yr to 34% at 10yr), caries rate (2 at 5yr to 8 at

10 yr), and in clinical micro-leakage (from 26% at 5 yr to 65% at 10 yr). In 19% of the

restorations, a clinically unacceptable marginal discolouration was observed at the 10 yr

recall. The primary reasons for clinical failure were fractures of the porcelain and large

marginal defects. However, most restorations were repairable, and only 4% needed to be

replaced. These total failures were present in veneered teeth with a large amount of lost

tooth tissue. The author concluded that porcelain veneers are not indicated in such teeth.

Aristidis and Dimitra (2002)31 reported on a case series of 186 porcelain veneers, 94% of

which were on anterior teeth. Veneers were assessed for marginal adaptation, marginal

discolouration, fracture rate, caries recurrence, and patient satisfaction. After a five year

follow up, 98.4% were clinically acceptable.

Sieweke et al (2000)32 did a retrospective study of 36 porcelain (IPS Empress ceramic)

veneer restorations of patients who had lost canine guidance. The mean age of patients

was 45.2 years. The dental work was done by six dentists at a dental school, and

preparation involved enamel reduction of 1 mm, and working an oval groove into the

dentin. The Kaplan-Meier survival rate at 6.5 yrs was 75.8%. The main causes of failure

were ceramic fracture and fracture of the adhesive bond.




Dumfahrt & Schäffer (1999)33 reported on the clinical performance of 191 veneers after 1

to 10 yrs in service (average service time of 4.6 yrs). The cumulative survival rate over 5

yrs was 97%, and after 10.5 yrs was 91%. There were seven failures, due to fracture or

multiple cracks. Worth noting is that when a failure occurred, parts of the preparation

surface were situated within dentin, although this finding was not statistically significant

(p=0.058). A finding that was significant was that the failure rate increased when the

finish line crossed an existing filling (p<0.01). Marginal defects were slightly detectable or

visible in 36% of cases, marginal discolouration occurred in 18% of restorations, and slight

gingival recession (0.1 to 0.5 mm) was observed in 31% of restorations, particularly when

the margins were equigingival or subgingival. Despite these defects at the margins, patient

satisfaction was high with 99% of patients rating aesthetics as excellent.

Walls (1995)34 reported the failure rate in a case series of 43 veneers (36 on anterior teeth,

7 on premolars) after follow-up of up to 5.4 yrs. The total failure rate was 14% and was

comprised of two complete failures, and four partial failures. The partial failures involved

loss of material from gingival extensions or from the incisal edge. There was little evidence

of marginal discolouration up to 3 years, however between 3 and 5 yrs, 28% of veneers

developed marginal discolouration which appeared to occur due to marginal leakage at the

luting agent to tooth interface.

5.2.3 The cause of veneer failure Refer to Table 6 for a summary of the cause of veneer failure. The most commonly

reported cause of failure was veneer fracture, and the incidence of irrepairable fracture

ranged from 0.5 – 5.5%, with the exception of one study reporting 11% failure32. In

comparison the incidence of repairable fractures was greater, ranging from 1.6% to 30%.

The next most commonly reported reason for failure of veneers was debonding, the

incidence of which ranged from 1.8 to 5.6%.


Table 5. Summary of Veneer studies.

Reference N anterior teeth

Veneer type

Follow-up

Effectiveness (survival/failure)

Definition of failure & clinical unacceptability

Comments

Burke and Lucarotti 200727

2,562 Porcelain 11 years 10 yr survival = 53% Patients <30 yrs and >60 yrs had poorest survival of veneers.

Repairable failure (implied) ‘Re-intervention required’.

Represents ‘on the street’ outcomes. Survival = no re-intervention required.

Fradeani et al 200528

182 Porcelain 12 years 12 yr survival = 94.4%

Irrepairable failure (stated) ‘fracture, partial debonding, impaired esthetics, impaired function’

Private practise. Marginal discolouration rated lowest

Smales & Etemadi 200429

110 Porcelain 7 years 7 yr survival = 95.8% (with incisal coverage) 7 yr survival = 85.5% (without incisal coverage)* *Difference not statistically significant

Irrepairable failure (implied) ‘fracture, debonding, colour mismatch’

Specialist prosthodontists

Peumans et al 200430

87 teeth (95% anterior, rest premolar)

Porcelain 5 & 10 years

5 yr clinical acceptance = 92% 10 yr clinical acceptance = 64% *Survival rate when repaired = 96%

Repairable failure (stated) ‘Clinically unacceptable’ Seven criteria were assessed.

A controlled university based clinical study. Primary reasons for clinical failure were fractures of porcelain and large marginal defects. Most restorations were repairable. Only 4% replaced.

Aristidis & Dimitra 200231

186 teeth (94% anterior, rest premolar)

Porcelain 5 years 5 yr clinical acceptance = 98.4% Irrepairable failure (implied) ‘Clinically unacceptable’ Seven criteria were assessed.

Dentist’s expertise level not stated. Reporting is brief.

Sieweke et al 200032

36 canines Porcelain 6.5 years 6.5 yr survival = 75.8% Irrepairable failure (implied) ‘Fracture, debonding, loss of function’

Six dentists at a dental school; restoration of lost canine guidance. Failures were ceramic fracture and fracture of adhesive bond.

Dumfahrt & Schäffer 200033

191 Porcelain 1 - 10 years

5 yr survival = 97% 10.5 yr survival = 91% Marginal defects detectable/visible in 36% of cases

Irrepairable failure (stated) ‘fracture, partial debonding, impaired esthetics or function’

Two dentists at a university clinic. Failures due to fracture or multiple cracks.

Walls 199534

43 (84% anterior, rest premolar)

Porcelain 5.4 years 5.4 yr survival = 86% Repairable failure (implied) ‘total loss of veneer or fracture requiring replacement….. plus partial failures where veneers retained’

University dental clinic.




Table 6. Cause of irrepairable veneer failure

Type of failure Study Incidence N Follow-up Comment

Veneer fracture (Irrepairable) Fradeani et al 2005 1.1% 182 12 yrs Veneers replaced Smales & Etemadi 2004 5.5% 110 7 yrs Four of the 6 fractures occurred in 1 patient Peumans et al 2004 2.3% 87 10 yrs Replaced with crown. Aristidis & Dimitra 2002 0.5% 186 5 yrs Sieweke et al 2000 11% 36 6.5 yrs Dumfahrt & Schaffer 2000 2.6% 191 10.5 yrs Walls 1995 2.3% 43 5.4 yrs

Veneer fracture (Repairable) Fradeani et al 2005 1.6% 182 12 yrs Limited fracture extension; these were rebonded Peumans et al 2004 30% 87 10 yrs Repairable fracture lines, and small bulk fractures. Walls et al 9.3% 43 5.4 yrs Fractures were repaired

Multiple cracks Dumfahrt & Schaffer 2000 1% 191 10.5 yrs

Debonding Smales & Etemadi 2004 1.8% 110 7 yrs Sieweke et al 2000 5.6% 36 6.5 yrs Walls 1995 2.3% 43 5.4 yrs

Colour mismatch Smales & Etemadi 2004 0.9% 110 7 yrs

Marginal Adaptation Aristidis & Dimitra 2002 0.5% 186 5 yrs

Loss of function Sieweke et al 2000 2.8% 36 6.5 yrs

Retreatment complication Peumans et al 2004 1.2% 87 10 yrs Restored with a crown after tooth fractured during endodontic treatment

Undocumented failure Sieweke et al 2000 2.8% 36 6.5 yrs Peumans et al 2004 1.2% 87 10 yrs


5.2.4 Adverse effects There were no serious adverse effects of veneer placement, other than the irreversible loss

of surface enamel during tooth preparation. Burke & Lucarotti (2008)27 do however

demonstrate the consequences of retreatment; approximately 20% of teeth with failed

veneers are retreated with crowns, which is a more invasive restoration presenting with a

new set of potential adverse effects and no guarantee of life-time success. One other study

also mentioned that three of the four failures were retreated with crowns30. The only other

adverse effects mentioned were:

Gingival recession

Caries at the veneer margin

Margin discolouration

Gingival recession: Two studies with 10 year follow-up periods reported that gingival

recession occurs on veneered teeth30 33. Peumans et al (2004)30 reported that an increased

tendency for gingival recession at the veneered tooth was already noticed after 5 yrs and

became more obvious at the 10yr recall. Similarly, Dumfarht and Schäffer (2000)33

described slight gingival recession in 31% of restored teeth. However, neither study

compared gingival recession of unrestored teeth in the same mouth, so it is not possible to

conclude a causal link between veneers and gingival recession. Nevertheless, that gingival

recession occurs is a consideration for the aesthetics of veneers in the long term.

Caries: Peumans et al (2004)30 reported a relatively low incidence of caries (2.3%) at 5

years, but this increased to 9.2% over 10 years. These caries were more prevalent where

veneers crossed an existing composite restoration. One other study of 186 veneers assessed

the caries rate and found no carious lesions31. One study excluded from this review

reported one carious lesion case out of 43 veneer restorations; it was repaired without

detriment to the veneer35.

Marginal Discolouration: Four studies reported that some veneers develop staining at the

margins. The incidence figures reported were: 28% at 5.4 yrs34, 17% at 4.6 yrs33 and 19% at

10 yrs30.



5.2.5 Patient Selection Criteria - Risk Factors for longevity Four risk factors for longevity of veneers were identified in the included studies. One of

these related to the amount of tooth structure remaining.

Patients >60 yrs and <30 yrs: Burke & Lucarotti (2008)27 showed that veneers

placed in people aged over 60 or under 30 had the poorest survival rates (p=0.003).

High caries rate: Burke & Lucarotti (2008)27 showed that veneers had the poorest

outcome in patients who have high caries activity (as evidenced by high annual

treatment costs and/or frequent attendances) (p<0.001).

Fillings at margins: Peumans et al (2004)30 reported that large marginal defects

were especially noticed at locations where the veneer ended in an existing

composite filling; and Dumfarht & Schaffer (2000)33 reported that the failure rate

increased when the veneer finish line crossed an existing filling (p<0.01).

Large amounts of lost tooth tissue: Peumans et al (2004)30 reported that all veneer

failures involved teeth with large amounts of lost tooth tissue.

There was some evidence, albeit statistically insignificant, that the survival rate of veneers

may be diminished when:

There is no incisal coverage29

There is dentin exposure33

5.2.6 Cost of Veneers The median cost of a porcelain laminate veneer in New Zealand is $844. ACC’s

contribution to the cost of Porcelain veneers is $675.80.

5.2.7 Methodological Quality Study Design: The methodological design quality of the veneer studies is low by evidence

based healthcare standards because the relevant studies were all case series, and only one

of the 8 studies was designed prospectively30. None of the studies is directly comparable

because of variations in almost every aspect of the studies: patient selection criteria,

number of patients, follow-up period, clinical setting and measurement and reporting of

outcomes.

Sample size and statistical analysis: Other than the large sample size of the English and

Wales general dental service (2,562 patients)27, the sample size for studies of porcelain



veneers ranged from 36 to 186. The Burke et al (2007)27 study utilised sophisticated

statistics in the analysis of data and had far greater statistical power due to the large sample

size, reporting p values between 0.001 and 0.003. Five studies27-29 32 33 calculated survival

rate using Kaplan-Meier statistics (or similar), and the other three studies30 31 34 calculated

percentages.

Intervention: All studies except one27 either described how the teeth and veneers were

prepared and luted, or stated that manufacturers instructions were adhered to. The

clinical setting in which the veneers were placed ranged from general dental practise, to

private specialist practise, and university dental clinics.

Study population, inclusion and exclusion criteria: As with the review of crowns, the

study population for veneers was not restricted to patients with fractured teeth because it

was not possible to isolate trauma-only patients from the study statistics, and none of the

studies reported solely on a trauma population. Not all studies stated the reasons for study

participants receiving veneers, but in those that did, the range of reasons included: tooth

defects, diastema, malalignment, discolourations, fractures, wear, minor malocclusions,

replacement of composite restorations and veneers. The veneered teeth were

predominantly anterior, however 4 studies also included a small proportion (5-16%) of

premolars30 31 34 36. Patient selection criteria, and inclusion and exclusion criteria was not

fully reported in some studies. The method of patient selection was primarily by selecting

consecutive patients treated between particular dates, except for the study by Burke &

Lucarotti (2008)27 which randomly selected the participant sample. Two studies did not

state how selection occurred34 36. Reasons for patient exclusion were not consistent across

the studies but the range of reasons included: patient drop-out32 34 36, poor oral health or

hygiene28 30, severe discolouration and evidence of marked or severe bruxism29, inadequate

remaining sound enamel29 30 36, and unfavourable occlusion30.

Follow-up and study period: Included studies had a mean follow-up period of at least 4

yrs, and the maximum reported follow-up was 12 yrs28. Two studies reported survival

rates at both short (5 yrs) and medium/long term (10 yrs) follow-up periods30 33. In studies

where the Kaplan-Meier survival rate was calculated, the follow-up period was the

maximum follow-up period calculated for that particular study, rather than the mean. One

of the main reasons for excluding veneer studies from this report was short follow-up

periods.



Outcome measures: The primary outcome measure for veneers was the survival/failure

rate. However, as with the crowns studies, there was variability in the way this was

defined (i.e. whether ‘failure’ includes repairable failures or not), and variation regarding

which criteria were used to assess a survival or failure. Other outcome measures widely

reported were aesthetics, and adverse effects; and one study discussed the implications of a

repair and the possible dental health outcomes over a lifetime27.

5.2.8 Clinical Outcomes The primary effectiveness outcome for veneers was the survival/failure rate, although there

was not a commonly used definition across all studies. Three studies defined failure as

repairable failure27 30 34, whereas the other five studies defined failure more narrowly as

irrepairable failure.

When only irrepairable failures were considered, (aside from Sieweke’s study32 confounded

by patients with lost canine guidance and reporting a low survival rate (75.8%)), the

survival rate was > 90% in four studies over a range of follow-up periods (5 to 12 years)28 29

31 33.

When repairable failures were included in the failure definition, the survival rate for

porcelain veneers was lower. Walls (1995)34 and Peumans et al (2004)30 reported survival

rates of 86% and 92% respectively at 5 years; but at 10 years Peumans et al (2004)30

reported a substantially lower survival rate of 64%, illustrating that veneers deteriorate

with time in service. However, it should be noted that most of the failed veneers in the

Peumans et al (2004) study were repaired and when this was taken into account, the

survival rate was 96% at 10 yrs. The figure of 64% survival in the study by Peumans et al

(2004) is not inconsistent with the 53% survival rate for porcelain veneers in England and

Wales’ general dental service over 10 years27. This study of veneers in a General Dental

Service has the highest external validity of all the veneer studies included in this review

because the results are representative of an entire service across a large sample size of

2,562 veneers. It is unknown whether these figures would be mirrored in New Zealand’s

‘on the street’ situation, but it is not unreasonable to expect that this would be the case.

Comment from Referee 1 I would suggest caution in comparing dental treatment decisions in the NHS in the UK with what occurs in New Zealand because the NHS has provided publicly funded dentistry whereas NZ dentistry is largely privately funded. Publicly funded dentistry can sometimes impose treatment guidelines and funding on dentists that effect some treatment decisions that may not occur in privately funded dentistry.



The effectiveness (survival rate) of veneers was diminished when:

the finish line of the veneer crossed an existing composite filling30 33

patients were aged less than 30 years or older than 60 years27

there is a high caries rate27

there are large amounts of lost tooth tissue30

The main causes of failure were fracture of the veneer, or debonding of the veneer.

Comments from Referee 2: The reference to debonding of veneers as major cause of failure (page 52) highlights one area of concern that could receive some additional attention but is difficult to investigate. Over time cement systems and bonding technology have changed significantly (this is also referred to in Section 6). Many studies neglect to mention how restorations were cemented but there are likely to be significant difference between traditional zinc phosphate cements, glass-ionomer cements and resin cements and also between how these cements perform in cementing different metals or ceramics to either enamel or dentine. The last paragraph in Section 8 which refers to this matter could perhaps be expanded to include some indication that this is a whole additional area of investigation, but that the quality of the clinical evidence is likely to be very poor as the materials are often very recently introduced and most studies have been conducted in vitro and their validity is difficult to assess.

5.2.9 Safety and adverse effects The most prevalent adverse effects of veneers are gingival recession and margin

discolouration. Whilst these effects are not considered unsafe, they do have a negative

impact on the aesthetics of the restoration, which may become a reason for either the

dentist or patient requesting additional restorations.

5.2.10 Implications for outcomes over a lifetime The life-time outcomes of restoring a tooth with a veneer could be deduced from only one

study27. The findings in the study of veneers in the England and Wales general dental

service demonstrated that approximately 10% of teeth with failed veneers were extracted,

and 20% were restored with crowns. The review of crowns in this EBH report has already

demonstrated that the survival rate of crowns is variable, and likely to be poor in the

general population, when placed by a general dental service.



5.3 Summary of Evidence All relevant studies about veneers were case series, hence the quality of evidence by EBH

standards is low.

The survival rate of veneers after 10 years of service varies greatly: at worst, survival rate is

53% - 64% if replacements and repairs are considered; and at best it is 96% if only

replacements are considered (i.e. repair rates are ignored).

There is evidence from multiple studies demonstrating that the short-term (~5 yrs)

survival rate of veneers ranges from 86% - 98%; (excluding the study by Sieweke (2000)

which had confounding patient factors).

There is evidence from three studies27 30 33 that the risk factors for the longevity of veneers

are patients aged <30 yrs or >60 yrs, a high caries rate, fillings at margins, and large

amounts of lost tooth tissue.

There is evidence from 7 studies indicating that the failure of veneers is caused primarily

by fracture of the veneer and debonding of the veneer.

There is evidence from numerous studies indicating that the main adverse effects of

veneers are gingival recession, margin discolouration, and caries at the veneer margin.

There is evidence from one study indicating that approximately 20% of failed veneers will

be retreated with crowns.




5.4 Conclusions The outcome measures in veneer studies are dominated by survival/failure rates, and the

results are conflicting. Data from studies using small sample sizes show that veneers

appear to be highly successful, but do deteriorate over time and large percentages of aging

veneers require repair28-31 33. Data from a large sample size in a general dental practise

indicate that a proportion of teeth (20% or more) in which veneers fail receive more

invasive restorations (crowns or extraction)27. The adverse effects of veneers (gingival

recession, margin discolouration) impact negatively on the aesthetic quality of veneers and

it is conceivable that these factors may have influenced the removal of veneers in the Burke

and Lucarotti (2008)27 study.


placement of veneers on anterior teeth. However, the data did identify four risk factors:

1. Veneers that cross an existing composite filling are at higher risk of failure.

2. Veneers placed in mouths with a high caries rate are at higher risk of failure.

3. Veneers placed in patients aged less than 30 yrs or older than 60 yrs have a higher

risk of failure.

4. Veneers are contraindicated for teeth with large amounts of tooth tissue have been

lost; [‘large amounts’ was not defined].


5.5 Appendix 2: Evidence Tables for Veneers Evidence Based Healthcare Table Veneers Reference: Burke & Lucarotti 200827 Bibliographic Number: Design Description Participants Intervention Outcomes

Description: The data set included patients:

whose date of acceptance was from January 1991 to March 2002.

Whose birthdays were included within a set of randomly selected dates, one of which was chosen in each year.

Whose treatment was on or after their 18th birthday.

Outcome Measures: Life of a restoration = interval between successive interventions. This interval was calculated using probabilities, as described in 2. Survival rate = % expected to survive after a given period, according to Kaplan-Meier method using ‘life of a restoration’ data. Definition of Re-intervention: the treatment that took place at the next intervention recorded for the veneered tooth. The re-intervention on a previously restored tooth may be associated with the original restoration, but it is nevertheless possible that there is no causal connection.

No. in Group: 2,562 anterior teeth in the maxilla. Age: most frequently in 30 to 49 age group.

Inclusions: Patients >18 yrs at time of crown treatment

Exclusions:

Results: 10 yrs: 53% of porcelain veneers survived without re-intervention Older patients (>60 yrs) and younger patients (<30 yrs) demonstrated poorer survival of porcelain veneers (p=0.003). Patients with high caries activity (high annual treatment costs/frequent attendance) (p<0.001). The treatments required at re-intervention are: ~10% recementation ~40% replacement by another veneer ~20% replacement with a crown ~20% replacement by a direct placement restoration (may or may not be associated with original veneer) As time since placement of original veneer progresses, the proportion of replacement veneers decreases, and the proportion of other restorations, including crowns, increases. Dentist factors (training year, experience) do not influence survival of porcelain veneers to re-intervention.

A retrospective analysis of a longitudinal sample of dental records of 2,562 porcelain veneer restorations placed in England and Wales over an 11 year period from 1990 to 2002. Dates of treatment for each tooth and date of next intervention for that tooth were consulted to calculate the time to re-intervention of teeth. The whole set of analyses was repeated on a second and non-overlapping random sample selected in the same way. Analysis was done using right-censored data. i.e. the end time of a restoration is not exactly known but is placed after a specified time, but without further limit. The method involved first estimating the probability that a patient will eventually return for re-treatment by analysing the observed patterns of re-attendance. This estimated probability of re-attendance can then be used to modify the standard Kaplan-Meier procedure to produce realistic estimates of the hazard of re-intervention. Selection Notes:

See paper for more details of methodological theory.

Placement of porcelain veneers on anterior maxilla teeth.




Evidence Based Healthcare Table Veneers Reference: Fradeani et al 200528 Bibliographic Number: Design Description


Description: Sample collected from consecutive patients at the authors’ offices. Treatment was for a variety of reasons. All restorations, except for one, were placed on vital teeth.

Outcome Measures: Mean follow-up 5.69 yrs Esthetics (colour match, marginal discolouration, marginal integrity; assessed according to CDA/Ryge criteria) Survival rate: Survival time being time from cementation to irreparable failure. (Kaplan Meier statistics). Irreparable failure included porcelain fracture and/or partial debonding that exposed the tooth structure and/or impaired aesthetic quality or function.

Group 1 No. in Group: 182 Mean Age: men 36.8 yr Women 38.3 yr

Inclusions:

Exclusions: Patients with uncontrolled parafunction, periodontitis, severe gingival inflammation, poor oral hygiene, or high caries rates.

Results: 5 restorations failed, 5.6%. (2 were replaced, 3 were rebonded). Survival probability (Kaplan Meier) 12 yr: 94.4%. 95% confidence interval from 100% to 89.4% Aesthetics were ‘satisfactory’. Marginal discoloration recorded the lowest proportion of ‘A’ ratings, but can be considered acceptable.

Retrospective case series

Selection Notes:

Restoration of anterior teeth with porcelain laminate veneers (Empress, and Vitadur Alpha). Work done between June 1991 and Dec 2002. Tooth prep ranged from 0.3 to 0.6mm in cervical third, to 0.8 to 1.0mm in the incisal third. The incisal reduction was up to 2 mm. Detailed methodology reported Follow-up occurred every 3 to 12 months.

Methodological Score: 3 Bias risk: study may not reflect a true ‘general population’ because only those with good oral health were included for analysis.



Evidence Based Healthcare Table Veneers Reference: Smales & Etemadi 200429 Bibliographic Number: Design Description


Description: Patients had tooth defects and discolourations, fractures, wear or minor malocclusions. In some instances, incisal wear had led to exposure of dentin.

Outcome Measures: Cumulative survival over 7 years (using life table method and SPSS stats software). Mean follow-up was 4 yrs. Failure = fracture, debonding, colour mismatch

No. in Group: 110 anterior teeth Age: older adolescent and adults

Inclusions: Randomly selected dental records from among those of the longest attending patients

Exclusions: Severe tooth discolouration, inadequate remaining sound enamel, evidence of marked or severe bruxism.

Results: Veneers with incisal coverage 7 yrs cumulative survival was 95.8%. Veneers without incisal coverage 7 yr cumulative survival was 85.5% Difference not statistically different. 6/9 failures occurred from porcelain fracture in veneers without incisal coverage. 4/6 fractures occurred in the one patient, who had worn incisal edges. All failures occurred within first 4 years.

A retrospective study of anterior porcelain laminate veneers placed with and without incisal coverage

Selection Notes:

Restoration of anterior teeth with porcelain laminate veneers. Some had incisal coverge, others did not. Work done by 2 prosthodontists at a specialist dental practice between 1989 and 1993. Where possible all preparations confined within enamel, but exposure of some dentin often occurred, especially in cervical tooth region.




Evidence Based Healthcare Table Veneers Reference: Peumans et al 200430 Bibliographic Number: Design Description


Description: Veneers were placed to improve aesthetics by replacing worn and discoloured composite restorations and veneers, or to correct discoloured, malformed and/or malaligned anterior teeth. There was a 93% recall rate at the 10 yr follow-up

Outcome Measures: Clinical acceptability Failure = clinically unacceptable but repairable; or clinically unacceptable with replacement needed. Esthetics, marginal integrity, retention, clinical microleakage, caries recurrence, fracture, vitality, patient satisfaction Follow-up at 5 year and 10 yrs.

No. in Group: 87 anterior teeth (includes first premolars) Age: 19 to 69 yrs

Inclusions: See description above. Patients treated with veneers in 1990 and 1991.

Exclusions: When less than 50% of the enamel remained for bonding or in patients with poor oral hygiene or unfavourable occlusion.

Results: Overall Clinically acceptable: 5 yrs: 92% (95 CI: 90 %to 94%) 10 yrs: 64% (95 CI: 51% to 77%). No veneers were lost. 4% needed to be replaced. Most restorations were repairable. Patient satisfaction: 59% patients very satisfied with esthetic result at 10 yr, compared with 80% at 5 yrs. Fracture rate: 4% at 5 yr, 34% at 10 yr Marginal integrity; large marginal defects in 20% (cause for failure). Especially noticed at locations where veneer ended in an existing composite filling. 14% excellent margin adaptation at 5 yr; 4% excellent margin adaptation at 10 yr. Clinical microleakage: 26% at 5 yr, 65% at 10 yr. 19% had clinically unacceptable marginal discolouration. Caries at veneer margin: 2 at 5 yr, 8 at 10 yr. Most caries (7/8) were observed where veneers crossed an existing composite restoration. Tooth vitality: 3 teeth needed endodontic treatment. They all had deep or large composite fillings.

A prospective clinical trial, set in a university dental school.

Selection Notes:

Restoration of anterior teeth and first premolars with porcelain veneers. Work done by one dentist in 1990 and 1991, following a meticulous clinical procedure. Feldspathic porcelain used. Labial enamel reduction was from 0.3 to 0.7 mm. incisal edge shortened and shoulder prepared on palatal side. Equigingival cervical margin.

Methodological Score: 3 Prospective, university based study, thorough reporting.



Evidence Based Healthcare Table Veneers Reference: Aristidis & Dimitra 200231 Bibliographic Number: Design Description


Description:

Outcome Measures: Teeth were assessed across 7 categories which dealt with aesthetics, marginal integrity, marginal discolouration, fracture rate, patient satisfaction. Ratings were perfect, clinically acceptable, or clinically unacceptable, but these terms were not further defined. 5 year follow up

No. in Group: 186 veneers. 94% anterior teeth, rest were 1st premolar Age range: 18 to 70

Inclusions: Not described

Exclusions: Not described

Results: Overall, 98.4% clinically acceptable. Marginal adaptation: 1/186 unacceptable Fracture: 3/186 fractured, 2 were acceptable, 1 was unacceptable. Patient satisfaction: 5/186 were not completely satisfied Marginal discolouration: 2/186 cases, but clinically acceptable. There was no caries recurrence.

A case series. Presumed to be restrospective.

Selection Notes:

Placement of porcelain veneers between Feb 1993 to Dec 1994. Work done by one dentist. Facial enamel reduced 0.3 to 0.5 mm, and incisal reduction was 0.5mm. Tooth preparation did not expose dentin.

Methodological Score: 3 Poorly reported



Evidence Based Healthcare Table Veneers Reference: Sieweke et al 200032 Bibliographic Number: Design Description


Description: Patients had a healthy periodontum and dentition free of caries and/or restored. The patients had lost canine guidance.

Outcome Measures: Survival rate using Kaplan-Meier method. Average follow-up period was 6.74 yrs. Failure = fracture, debonding, loss of function. It is implied that only irrepairable failures are reported in statistics.

No. in Group: 36 canines (in 17 patients) Mean Age: 45.2 yrs

Inclusions: The patients had lost canine guidance.

Exclusions: Patients who did not participate in or dropped out of the recall program

Results: Survival rate: 6.5 yrs: 75.78% 95% confidence intervals were 58% to 88% 8 veneers failed. Cause of failure: 4/8 ceramic fracture 2/8 fracture of adhesive bond 1/8 loss of function 1/8 not documented

Retrospective case series

Selection Notes:

Restoration of canine guidance using oroincisal IPS Empress ceramic veneers. Minimal thickness of enamel reduction was 1 mm. Oval groove also made into the dentin. Patients were recalled 6 monthly. Work done at a dental school by 6 dentists, between 1992 to Jan 2000.




Evidence Based Healthcare Table Veneers Reference: Dumfahrt & Schaffer 2000; and Dumfahrt 199933 36 Case Number: Bibliographic Number: Design Description


Description: Reasons for treatment were: worn anterior teeth (80) surface enamel defects(34), intrinsic discolouration (30), hypoplasia (22), occlusal correction (13), diastema (13), fractured teeth (9), and mild malalignment (4).

Outcome Measures: Average observation period was 4.6 yrs. Survival time = time from placement to irrepairable failure. Veneers assessed following a modified California Dental Association/Ryge criteria. Kaplan Meier survival statistics applied.

No. in Group: 191 teeth (94% anterior) Age: 13-63 yrs; largest number in 31-40 age group.

Inclusions: Non-carious surface defects, discolourations, and minor to moderate structural defects.

Exclusions: 7 patients who were unavailable for final evaluation between Sept and Dec 1997. Teeth with structural enamel defects that would leave insufficient enamel and tooth structure, such as amelogenesis and dentinogenesis imperfecta. Cases where less than 50% of the potential bonding area was within the enamel as a result of large areas of exposed dentin or large restorations.

Results: Failures: 5 fractures, 2 multiple cracks Kaplan Meier Survival estimation 5 yrs: 97% 10.5 yrs: 91% Failure rate significantly increased when the finish line crossed an existing filling (p<0.01). When a failure occurred, parts of the preparation surface were situated within dentin. Findings not significant (p=0.058). Marginal integrity: 99% acceptable; 36% showed slight detectable and/or visible marginal defect. Facial marginal integrity was worse when the prepared gingival margin located within dentin. Marginal disintegration: significantly increased for longer wearing time (p<0.05). Superficial marginal discolouration: in 17% of veneers. Significantly increased when gingival preparation was located within dentin (p<0.001). Gingival recession: increased recession in 31% of veneers; 88% of these were in teeth with equigingival or subgingival margins Patient satisfaction: 99% excellent aesthetics

A retrospective case series

Selection Notes:

Restoration of anterior teeth with porcelain laminate veneers. Two dentists did the restorations and examinations at a university dental clinic. Consensus was reached when disagreements over scoring occurred.





Evidence Based Healthcare Table Veneers Reference: Walls 199534 Case Number: Bibliographic Number: Design Description


Description: Patients had worn or fractured teeth

Outcome Measures: Failure = total loss of the veneer or such severe fracture that the restoration had to be replaced. Follow-up: the minimum time was 50 months (4.16 yrs), the max was 65 months (5.4 yrs)

No. in Group: 43 veneers (36 on anterior teeth, 7 on premolars) Mean Age: not stated

Inclusions: Twelve patients presented to a dental hospital with problems involving tooth-wear and/or localised tooth fracture.

Exclusions: 9 restorations lost to follow-up.

Results: 2 complete failures (one after 2 days; poor prep blamed) (4.7%) 4 partial failures (loss of material from gingival extensions or from the incisal edge) (9.3%) Total failure=14% Marginal stain 0-3 yrs: little evidence 3-5 yrs: 12/43 (28%) veneers developed marginal discolouration

A case series. Presumed to be retrospective.

Selection Notes:

Restoration of teeth with porcelain veneers. Acid etch technique used along with dentine-bonding system. University dental clinic. Patients were reviewed at 6 month intervals.



6 Composite resin restorations

6.1 Health Technology Composite resins used in dentistry to restore carious, worn or fractured teeth are

composed of an organic resin-based matrix and an inorganic filler. In the restoration of

fractured teeth, they are used in both the build-up of the remaining crown tissue, and in

the reattachment of avulsed fragments. The methods of both of these treatment

approaches have evolved over the last 30 years as successive generations of composite

resins and adhesive products that can form strong bonds with enamel, and latterly dentine,

have been developed.

The earliest method for reattachment of avulsed fragments, reported in 197837 38, involved

preparation of the tooth and fragment by an enamel acid-etch technique followed by

adhesion of fragments using composite resin. Acid etching produces micro-porosities in

the enamel surface into which low viscosity adhesives can penetrate resulting in a

mechanical bond with the tooth. The method was further advanced in the mid 1980’s

when dentine bonding agents were developed to increase the bond strength of composite

resins to dentine, and since then there have been several generations of development.

Various additional techniques have been employed to enhance dental fragment retention

after reattachment and these include enamel bevels, internal enamel or dentine grooves,

chamfers and over-contouring39.

6.2 Results 6.2.1 Description of studies The majority of composite resin literature is about fillings. Seventeen papers were selected

for critical appraisal; none of these were RCT’s or studies which compared composite resin

methods with crowns, veneers or bleaching.

After a critical appraisal of the studies, 13 were excluded and 4 included. All 4 included

papers were case series with a sample size ranging from 18 to 334, and a follow-up period

ranging from 2 to 7.5 years. These studies reported the use of both fragment reattachment

and composite build-up. The primary outcome measure reported by all four of the

included studies was retention rate or survival of the restoration and two studies reported



on pulpal health and aesthetics. Composite resin restoration was the only intervention for

which indications/contrindications were presented regarding the type of fracture, and the

extent of fracture.

The characteristics of the excluded studies are presented in Appendix 6.

6.2.2 Clinical Outcomes The results of 4 studies about composite resin restorations of fractured teeth are presented

here. For a summary of results refer to Table 7. Further details of each study can be

found in evidence tables in Appendix 3.

Spinas (2004)40 did a seven year follow-up study of 90 injured teeth in children and

adolescents. Seventy teeth received a composite resin build-up, and the remaining 20

received fragment reattachment treatment. The acid-etch conditioning technique was used,

along with 3rd or 4th generation adhesive systems. Ten parameters of effectiveness were

evaluated before each restoration was assigned a final overall evaluation. Of the composite

resin build-up restorations, 47% needed a complete replacement after 3 years, and 100%

needed complete replacement after 7 years. The study showed that composite build-up was

more reliable for injuries of class C: involving the incisal edge and at least a third of the

crown, when compared to injuries of class B: involving a mesial or distal coronal angle

and/or incisal edge. A difference in treatment reliability was also observed when fragments

were reattached, except that the situation was reversed: class B injuries were more durable

than class C with this treatment. After 3 years there were no replacements of

reattachments required for class B injuries, whereas 61% of class C injuries required

complete replacement. By 7 years after reattachment, 100% of both class B and C injuries

needed a complete replacement. The authors were of the opinion that a tooth can

probably undergo 3 or 4 composite restoration replacements before it shows a severe

reduction of its adhesive properties; although they did not provide clinical evidence to

support that particular opinion.

The most frequent events that led to a replacement restoration were loss of the restoration,

loss of marginal integrity, and unacceptable pigmentation/discolouration caused by pulp

necrosis secondary to initial injury. The authors opinion was that the greatest limitation

of composites is poor quality of the marginal seal. Interestingly, a great number of

restoration losses were due to 2nd or 3rd successive injuries. Consequently a risk factor



for longevity of composite resin restorations is teeth with anatomical factors predisposing

to further traumatic injury (overjet, overbite, Angle’s Class II malocclusion).

Garcia-Ballesta et al (2001)41 reported clinical outcomes for a group of 18 children who

had avulsed coronal fragments reattached. In addition to the standard acid-etching, use of

a bonding agent and light-curable composite resin, a notch was also made in the enamel in

an effort to improve bonding strength. The retention rate after 2 years was 39%. The

mean retention period was 19.5 months, but varied depending on the amount of dentin

exposure. Where there was little to moderate dentin exposure (n=10), the mean retention

period was 22.1 months, whereas where there was wide dentin exposure (n=8) the mean

retention period was shorter, being 15.1 months.

Cavalleri & Zerman (1995)42 reported the 5 year outcomes of 84 fractured incisors in

children aged from 6 to 12 years. Teeth were restored either with reattachment of avulsed

fragment or with composite resin build-up. Pulpal exposure occurred in 16% of injuries;

fractures involving fracture of enamel and dentine occurred in 80% of injuries. Of those

without pulp involvement, 6% developed pulp necrosis. This was a significantly different

result (p<0.01) compared to injuries that exposed the pulp, of which 57% developed pulp

necrosis. The restorations were aesthetically satisfactory in 43% of teeth. A high

proportion (40%) of teeth were retreated because of a new trauma, and 17% of restorations

were unsatisfactory due to wear of the composite.

Andreasen et al (1995)43 reported the results of a multi-center case series study of 334

fractured anterior teeth restored by reattachment of the avulsed fragment. The study

compared the effectiveness of two bonding methods: acid etching of enamel alone (AE)

and a combination of enamel etching and dentinal bonding (DBA). The extent of fracture

had no influence on loss or retention of fragments, but the treatment method did. The

final retention rate at 7.5 years was similar for each group: 15% for AE and 25% for DBA.

However, it took three times longer to reach 50% retention in the dentinal bonding group

(2.5 years compared to 1 year). The aesthetics, as judged by colour harmony between the

tooth, the fragment and the composite at the fracture line, was acceptable in 55% of DBA

cases, and in 45% of AE cases. Fragment loss was predominantly caused by new trauma

(~50%), non-physiologic use of the bonded tooth (~12%), and horizontal traction (i.e.

biting into chewy or tough foods). About 25% were lost spontaneously or during

physiological use. Although there was pulpal involvement in 39.5% of injuries, this was




not an indicator of subsequent pulpal necrosis. Pulp canal obliteration and pulpal necrosis

occurred in 6.6% of cases and was apparently related to a concomitant luxation injury, not

to a complicated crown injury exposing pulp.


Table 7. Summary of composite resin studies

Reference N teeth

Composite Usage Follow-up (yrs)

Effectiveness (retention rate/ survival of restoration, pulpal health, esthetics)

Comments

Spinas 200440 90 Composite build up Reattachment (acid etch + 3rd or 4th generation adhesive systems used)

7 Build-up 3 yr: 47% needed complete replacement 7 yr: 100% needed complete replacement Reattachment 3 yrs: B grade injuries 0% needed replacement C grade injuries 61% needed replacement 7 yrs: 100% needed complete replacement A great number of restoration losses due to a new trauma

Patients were children & adolescents. Detailed analysis; many subgroups considered. C type injuries involve loss of more coronal structure (at least a third).

Garcia-Ballesta et al 200141 18 Reattachment (acid etch + dentin bonding)

2 2 yr: 39% retention rate mean retention period little/moderate dentin exposure: 22.1 months wide dentin exposure: 15.1 months

Patients were children. The less dentin exposed, the longer the tooth fragment remained attached.

Cavalleri & Zerman 199542 84 Composite build up Reattachment (acid-etch)

5 5 yr: 43% intact and esthetically satisfactory 17% unsatisfactory 40% retreated due to a new trauma Pulp necrosis was most prevalent in injuries which exposed the pulp.

Patients were children.

Andreasen et al 199543 334 Reattachment; (study compares acid etch with acid etch + dentin bonding agent)

7.5 7.5 yr: 15% retention for acid etch group 25% retention for acid etch + dentin bonding group 50% loss of retention took longer to reach in the dentin bonding group 50% fragment loss due to a new trauma. Pulp necrosis (6.6%) not associated with pulp exposure (39.5%), but rather to a concomitant luxation injury.

Mean patient age ranged from 10.5 yrs to 14.5 yrs.



6.2.3 Adverse effects No adverse effects were reported for the use of composite resin. Any negative outcomes

with this treatment were related to effectiveness.

6.2.4 Patient Selection Criteria - Risk factors for longevity Three possible risk factors for longevity of reattachment of avulsed fragments using

composite resin were identified or discussed.

Fractures involving the incisal edge and at least a third of the crown fail quicker

than fractures involving a mesial or distal coronal angle and/or incisal edge40.

Anatomical factors predisposing to further traumatic injury (overjet, overbite,

Angles class II malocclusion). Three of the four studies reported that 40-50% of

fragment loss occurred due to a new trauma40 42 43.

Wide exposure of dentin: There is conflicting evidence regarding the influence of

dentin exposure. One study reported that restorations failed quicker (mean life

was 15 months) when there was wide dentine exposure; as compared to

restorations with little/moderate dentin exposure (mean life was 22 months)41.

However, this study had only 18 participants and it is unknown whether this is a

statistically significant finding. In contrast, a study with 334 participants showed

that the extent of fracture had no influence on loss or retention of fragments43.

In addition, there was conflicting evidence from two studies about the influence of pulp

exposure on pulp survival in teeth restored with composite resin42 43. Cavalleri & Zerman

(1995)42 reported up to 57% pulp necrosis when pulp was exposed, and that injuries with

pulp involvement had a significantly higher chance of pulp necrosis (p<0.01). In contrast,

Andreasen et al (1995)43 reported that pulpal necrosis occurred in only 6.6% of cases and

was apparently related to a concomitant luxation injury, not to a complicated crown injury

involving pulp exposure. This difference in the outcome for teeth with pulp involvement

is possibly also due to a robust treatment of exposed pulp by Andreasen et al (1995)43.



6.2.5 Indications for improved longevity Composite resin build-up

Fractures involving the incisal edge and at least a third of the crown: composite

resin build-ups were more reliable for injuries of this class compared to fractures

involving a mesial or distal coronal angle and/or incisal edge.

Composite resin reattachment

Fractures involving a mesial or distal coronal angle and/or incisal edge:

reattachment of tooth fragments more durable for injuries of this class compared to

fractures involving the incisal edge and at least a third of the crown.

6.2.6 Cost of composite resin restorations Composite restorations for 50% or more of the tooth costs $295. [Awaiting further price

data for this section].

6.3 Discussion 6.3.1 Methodological Quality Study Design: The methodological design quality of the composite resin studies is low by

evidence based healthcare standards because the four relevant studies were all case series.

None were designed prospectively. None of the studies is directly comparable because of

variations in almost every aspect of the studies: patient selection criteria, number of

patients, follow-up period, and type of intervention. There were a number of individual

case studies (8) excluded from this review because of their comparatively low quality of

evidence.

Sample size and statistical analysis: The sample size in the four studies of composite

resin restorations ranged from 18 to 334. Two studies did no statistical analysis except for

calculating percentages40 41. One study applied the chi-squared test to analyse pulp survival

in two subgroups of participants42; and one study applied the Student’s t-test and chi-

squared test, employing 95% confidence intervals, to analyse fragment retention times43.

Intervention: Two studies reported using composite resin both to reattach avulsed tooth

fragments, and to rebuild tooth structure where fragments were lost40 42, whereas two

studies reported using composite resin to only reattach avulsed tooth fragments41 43. All



studies employed the ‘acid-etch technique’ and mentioned whether or not dentin bonding

agents were used. Only one study stated the ‘generation’ of adhesive system that was

used40. The descriptions of the intervention were generally quite broad; only one study

described the intervention in sufficient detail that the treatment could be replicated41.

Study population, inclusion and exclusion criteria: The study populations were young

people aged from 6 to 18 yrs, and limited to patients with fractured anterior teeth. One

study classified the study participants according to the type of injury sustained, using a

more precise method than the Andreasen system40. Two studies excluded crown fractures

associated with other complications such as root fracture or luxation41 42. The other two

studies did not describe exclusion criteria40 43.

Follow-up and study period: By comparison with the other interventions already

described in this review, the follow-up period for composite resin restorations is short-

term, ranging from 2 to 7.5 yrs.

Outcome measures: The main outcome measure for composite resin restorations was the

survival of the restoration. This was presented in various ways: either as retention time; or

the percentage retained or successful at certain follow-up periods; or time taken to reach

50% retention. Two studies also reported on pulp survival, the aesthetics of the

restorations, and reasons for failure of composite resin restorations 42 43.

6.3.2 Clinical Outcomes Overall, the retention/survival rate of either composite resin build-up restorations, or

reattachment of tooth fragments is poor, indicating that these treatments can not be

considered as long-term restorations. Spinas (2004)40 reported that 100% of restorations

needed complete replacement after 7 yrs, Andreasen et al (1995)43 reported that between

75 and 85% of restorations had been lost after 7.5 years, and Cavalleri & Zerman (1995)42

reported that 57% of restorations were either unsatisfactory or were replaced after 5 yrs.

Garcia-Ballesta et al (2001)41 reported only a 2 yr follow-up period, and by then the

retention rate was only 39%.

6.3.3 Safety and adverse effects There were no safety concerns raised or adverse effects reported.



6.3.4 Implications for outcomes over a lifetime Fractured teeth treated with composite resin restorations will require retreatment.

Although the timing of retreatment will be uncertain for each case, the evidence presented

above suggests that retreatment would be required for most teeth within 7 years (at best),

and within 2 years at worst. The author of one study believes that a tooth can probably

undergo 3 or 4 composite resin replacements before it shows a severe reduction of its

adhesive properties; however they did not provide clinical evidence to support that

opinion40.

Restoration of teeth with composite resin would appear not to place limitations on future

retreatment options.

6.4 Summary of Evidence There is low quality evidence from case series to suggest that the survival of composite

resin restorations is poor, either by reattachment of avulsed fragments or by building up

the tooth structure; and patients should expect to require retreatment within 2 to 7 years.

Composite resin restorations of fractured teeth appear to be safe, and patients suffered

from no adverse effects.

Despite the short-term survival of composite resin restorations, there is evidence from one

case series that fractures involving the incisal edge and greater than a third of the crown,

have a better treatment outcome when built-up with composite resin. Whereas, fractures

involving a mesial or distal coronal angle and/or incisal edge have a better treatment

outcome when tooth fragments are reattached.

There is evidence from three studies40 42 43 showing that 40-50% of reattachment failures are

due to a new trauma (severity of new trauma not described), indicating that this treatment

is not durable or strong enough to withstand trauma. Teeth with anatomy predisposing

them to further trauma were identified as a risk factor for longevity of fragment

reattachment.

There is equivocal evidence about the influence that dentin exposure has on the longevity

of fragment reattachment.




6.5 Conclusions Composite resin restorations appear to have limited longevity and are not suitable as

permanent restorations. However, they are not associated with adverse effects and can be

readily replaced without negatively reducing the options for future retreatment the tooth.


placement of composite resin on fractured anterior teeth.


6.6 Appendix 3: Evidence Tables for composite resin restorations Evidence Based Healthcare Table Composite resin Reference: Spinas 200440 Bibliographic Number: Design Description


Description: 90 injured teeth, all with crown fractures of varying severity. Injuries were classified using a more precise method than the Andreasen system44. Class A: injury limited to only enamel which includes a mesial or distal coronal angle, or only the incisal edge Class B: involving the enamel-dentin which involves a mesial or distal coronal angle and incisal edge. When pulp exposed defined as subclass B1. Class C: involving enamel-dentin with incisal edge and at least a third of the crown. When pulp exposed defined as subclass C1. Class D: involves enamel-dentin with a mesial or distal coronal angle and the incisal or lingual surface, with root involvement. When pulp exposed defined as subclass D1. Whenever fractured tooth presents a necrotic pulp, defined with addition of ‘h’. Class B and C were most frequent injuries

Outcome Measures: 7 year follow up. Ten parameters were evaluated before restoration was assigned one of 4 evaluations: Optimal: no complications or functional or aesthetic problems Good: minor changes occurred, eliminated with simple polishing. Acceptable: slight discomfort or dissatisfaction or colour alterations or ditching between enamel and composite. May need a partial replacement Not acceptable: major discomfort, or poor marginal integrity, poor aesthetic qualities, or loss of restoration, or need for endodontic treatment. Needs an immediate and complete replacement.

Group 1 - composite build-up No. in Group: 70 Position in mouth not stated, presumably anterior. Age: 8-18 yrs

Group 2 - fragment reattachment No. in Group: 20 Position in mouth not stated, presumably anterior Age: 8-18 yrs

Inclusions: Complete clinical diary, from moment of injury to last check-up. Initial photographic and radiographic images All treatments made by same dentist Patients signed an informed consent for future treatments

Exclusions:

Results: Composite restorations C class more reliable than B class 3 yr: 47% needed a complete replacement 7 yrs: 100% needed complete replacement Of those with replacements, at 6 yrs, 48% needed further complete replacement. Reattachments B class more durable than C class. 5 yrs: About 70% needed complete replacement. 7 yrs: 100% needed complete replacement; 45% replaced for a second time. (some replaced with composite resin rather than fragment). Of those replaced, by 7 years about 50% needed further complete replacement. Class B and C tend to get worse while undergoing repairs: each time tooth is treated, is an inevitable loss of dental tissues; may have tendency to become subclass ‘1’ or ‘h’. A tooth can probably undergo 3 or 4 composite restoration replacements before it shows severe reduction of its adhesive properties.


Selection Notes:

Resin-based composite restorations, or, reattachment of original fragment. Used total-etch conditioning technique and 3rd or 4th generation adhesive systems.




Evidence Based Healthcare Table Composite resin Reference: Garcia-Ballesta 200141 Bibliographic Number: Design Description


Description: Children with fractured teeth. Varying degrees of dentin exposure. In all cases apices were immature to some degree.

Outcome Measures: Retention over time

No. in Group: 18 anterior teeth Mean Age: 8.6 yrs

Inclusions: Uncomplicated crown fractures.

Exclusions: Two teeth with comminuted fractures were unsuitable for restoration. Cases presenting with other associated lesions (root fracture, luxation) in addition to crown fracture. Cases seeking treatment more than 5-6 hours post accident because the coronal fragment could have become dehydrated.

Results: 1 month: 94% retention 2 yrs: 39% retention Mean retention period was 19.5 months, but varied depending on amount of dentin exposure: little/moderate dentin exposure (n=10) = 22.1 months wide dentin exposure (n=8) = 15.1 months

A case series. Presumed to be retrospective.

Selection Notes:

Reattachment of avulsed fragment. A notch was made in the enamel at an angle of 45 degrees; the tooth and fragment were then prepared with acid-etching, and bonded using a dental adhesive, and light-curable composite resin.




Evidence Based Healthcare Table Composite resin Reference: Cavalleri & Zerman 199542 Bibliographic Number: Design Description


Description: 95% of injured teeth were maxillary central incisors; most injuries were in 8 year olds; sex ratio was 3.6:1 for boys and girls. 80% injuries were fracture of enamel and dentine without pulpal exposure 16% injuries were fracture of enamel and dentine with pulpal exposure 4% injuries were fracture of enamel 40% of injuries occurred in patients with maxillary overjets more than 3mm.

Outcome Measures: 5 year follow-up Pulpal health Esthetics Survival of restoration

No. in Group: 84 incisors Age range: 6-12 years

Inclusions:

Exclusions: Crown-fractured incisors associated with subluxation, luxation, root and/or crown-root fractures

Results: Survival of restoration: 40% of teeth were retreated because of a new trauma. 43% of restored teeth were deemed esthetically satisfactory 17% were unsatisfactory due to wear of the composite Only 1 case required rebonding of a fragment Pulp survival: Injuries without pulp involvement: 6% had pulp necrosis Injuries with pulp involvement : 57% had pulp necrosis (The difference between these results is statistically significant according to chi-squared test, p<0.01.)

A restrospective case series.

Selection Notes:

12% of cases had fragment reattached 46% of cases had acid-etch composite resin build-up 38% of cases had composite restorations subsequent to dentin coverage, pulp capping, or coronal pulpotomy 3.6% of cases received enamel grinding





Evidence Based Healthcare Table Composite resin Reference: Andreasen et al 199543 Bibliographic Number: Design Description


Description: Permanent incisors with fractures of the crown or crown and root. (3.8% had root fractures). There was pulpal involvement in 39.5% of injuries. Age ranged from 6.5 yrs to 43.4 yrs. Mean age in dentinal bonding group was 14.5 years. Mean age of acid-etching group was 10.5 years.

Outcome Measures: Retention rate Esthetics (fracture line visibility; colour harmony between fragment and tooth) Pulp status

No. in Group: 334 teeth Mean Age: 14.5 yrs in dentinal bonding group; 10.5-10.6yrs in acid-etch group.

Inclusions: Not stated

Exclusions: Not stated

Results: The extent of fracture had no influence on loss or retention of fragments in either treatment group. Retention Rate: Final retention rate was similar for each group (15% in AE, 25% in DBA at 7.5 years). 50% retention rate took 3 times longer to occur in the dentinal bonding group. (2.5 yrs compared to 1 yr). Esthetics DBA: acceptable in 55% AE: acceptable in 45% Cause of fragment loss: Predominantly caused by new trauma, non-physiologic use of the bonded tooth, and horizontal traction (biting into chewy/tough foods). 25% lost spontaneously or during physiological use. Pulp status: Pulp canal obliteration and pulpal necrosis occurred in 6.6% of cases and was apparently related to a concomitant luxation injury, not to a complicated crown injury involving pulp exposure.

A multicenter clinical study (case series). Presumed to be retrospective.

Selection Notes:

Reattachment of dental fragments. 44% had acid etching of enamel alone for fragment bonding (the AE group). Work performed in one of two clinics. 56% had a combination of enamel etching and dentinal bonding (the DBA group). Work performed in a third clinic. In cases where multiple tooth fractures occurred (6%), one tooth received reattachment, the other received composite build-up. For fractures approaching pulpal exposure, or actually exposing pulp, the tooth fragment was wet-stored for up to 3 months before reattachment.



7 Intra-coronal Bleaching

7.1 Health Technology The active agent in tooth bleaching is hydrogen peroxide and its use in tooth bleaching

was first reported in 188445. Hydrogen peroxide is an oxidising agent that releases free

radicals that can break unsaturated double bonds of long, coloured molecules, or reduce

the coloured metallic oxides like Fe2O3(Fe3+) to colourless FeO(Fe2+) (reviewed by Attin et

al, 200346). Hydrogen peroxide is either applied directly or is produced in a chemical

reaction from sodium perborate or carbamide peroxide. Intra-coronal bleaching, also

know as non-vital bleaching, is the process whereby discoloured non-vital teeth are

bleached internally. There are three general approaches to achieve intra-coronal bleaching:

1) via the ‘walking bleach’ technique; or 2) via a quicker in-office technique, or 3) via a

combination of both these techniques. The ‘walking bleach’ technique is performed by

sealing bleach (typically sodium perborate in either its monohydrate or tetrahydrate form),

and either water or 3% hydrogen peroxide) inside the pulp chamber for several days,

whereas in-office bleaching involves filling the pulp chamber with cotton soaked in 30%

hydrogen peroxide. The practise of using heat to activate bleach during the in-office

treatment (‘thermo-catalytic’ bleaching) is no longer advocated by some authorities due to

safety concerns over the use of high concentrations of bleach in combination with heat46 47.

7.2 Results 7.2.1 Description of Studies The majority of tooth bleaching literature pertains to the bleaching of vital teeth, and

covers the use of gels, pastes, strips and night-guards. There are fewer studies about the

bleaching of non-vital teeth, and they can generally be categorised into those about teeth

either discoloured with tetracycline staining or discoloured as a result of trauma and/or

root-canal treatment.

There were no RCT’s or comparative studies identified. Fifteen papers were selected for

critical appraisal, after which 4 case series studies were retained for inclusion in the main

review. Additionally one other paper was included in the adverse effects section; the

remaining 10 studies were excluded. The number of participants ranged from 21 to 86

and the follow-up period ranged from 1 to 8 years. Interestingly, although the current

recommended internal bleach method typically utilises sodium perborate-(tetrahydrate)

mixed with either water or 3% hydrogen peroxide46 47, none of the included studies used



this mixture; they used 30 or 35% hydrogen peroxide either alone or mixed with sodium

perborate.

The primary outcome measures reported were tooth colour change, success/failure and

patient satisfaction. However, the definition of these outcome measures was not always

well defined and there was little consistency of the definitions between studies, with the

exception being ‘failure’. When failure was reported it was broadly defined as being teeth

that demonstrated little or no change in colour. The reporting of patient selection and

bleaching methods was not of a consistently high standard.

The characteristics of the excluded papers are presented in Appendix 6.

7.2.2 Clinical Outcomes The results of 4 studies about intra-coronal bleaching are presented here, and they are

grouped according to the bleach technique used. For a summary of results refer to Table 8.

Further details of each study can be found in evidence tables in Appendix 4.

Walking Bleach

Glockner et al (1999)48 reported successful results 4.8 years after 86 patients with

discoloured anterior teeth were treated by the walking bleach technique (using sodium

perborate/30% hydrogen peroxide). Using subjective observations, overall, 66.2% of

treatments were successful according to dentists, whereas patients judged that 91.9% of

treatments were successful.

Waterhouse & Nunn (1996)49 performed the walking bleach technique (using sodium

perborate/30% hydrogen peroxide) on 21 endodontically treated discoloured central

incisors in children and adolescents. After 18 months follow-up 62% of patients were

satisfied and the number of gray reddish gray or off-guide teeth had decreased from 97% to

57%. Stability of shade was displayed in 83% of teeth, and 17% showed some re-

discoloration. Failure occurred in 29% of cases. One tooth had minor and stable apical

resorption prior to bleaching, which remained non-progressive 18 months after bleaching.

Walking bleach and thermocatalytic bleaching combination

Friedman et al (1988)50 reported a 79% success rate 1-8 yrs following internal bleaching of

58 non-vital anterior teeth using 30% hydrogen peroxide. Thirty five percent received




walking bleach treatment, 22% received thermocatalytic treatment and 43% received both

treatments. A successful treatment included teeth which matched the colour of the

adjacent teeth, and those that had some discolouration but were acceptable to the patient.

There was a 6.9% incidence (4 teeth) of external tooth resorption.

Thermocatalytic bleaching

Deliperi & Bardwell (2005)51 bleached 25 anterior teeth (having shades of A3 or darker

according to a Vita shade guide) using a combination of thermocatalytic bleaching with

35% hydrogen peroxide and at-home custom tray bleaching with 10% carbamide peroxide.

Two weeks after the treatment 100% of teeth improved by at least 8 Vita shades. Colour

stability was assessed 2 years later. The mean shade values at baseline, 2 week follow-up

and 2 year follow-up were 14.4 (±1.9), 1.6 (± 0.7) and 2.8 (± 1.7) respectively. At the two

year recall a shade rebound to a darker shade of up to 4 shades was evident in 13/25 teeth.

Tooth colour was stable in 12/25 teeth.


Table 8. Summary of intra-coronal bleach studies Reference N

teeth Method/Agent Follow-up

(yrs) Effectiveness (success/failure, patient satisfaction, colour stability)

Adverse events

Deliperi & Bardwell 200551 25 Thermocatalytic: 35% H2O2, Followed by at home custom tray: 10% carbamide peroxide

2 100% of teeth improved by at least 8 Vita shade values 48% of teeth retained their new shade

Not reported

Glockner et al 199948 86 * Walking bleach: sodium perborate + 30% H2O2

4.8 91.9% success judged by patient 66.2% success judged by dentist Failure=little or no colour change

Not reported

Waterhouse & Nunn 199649

21 Walking bleach: sodium perborate + 30% H2O2

1.5 62% patient satisfaction 29% failure Failure=no colour change, or veneered 83% displayed stability of shade

No evidence of cervical or progressive apical resorption

Friedman et al 198850 58 25%: Walking bleach: 30% H2O2 22%: Thermocatalytic: 30% H2O2

+ heat 43%: Walking bleach + thermocatalytic

1 - 8 79% success 21% failure Failure=discoloration, requiring further treatment

6.9% external tooth resorption

* this paper reported N as patient number, not tooth number



7.2.3 Adverse Effects The most serious adverse effect of internal bleaching is external tooth resorption.

Friedman et al (1988)50 reported an incidence of 6.9%. An article by Heithersay (1994)52

which was not included in this review because it did not report success/failure outcomes,

reported an external tooth resorption incidence of 2.5%.

The association of external tooth resorption with bleaching has been reviewed

extensively46 53-56, and is also reported in a number of studies published in the early 1980s.

Because the latter were published prior to 1987, they are not included in this review. The

consensus view is that the risk of tooth resorption is higher if hydrogen peroxide at high

concentrations (30%) is used, and the risk further increases when 30% hydrogen peroxide

is combined with heat46 53-56. It has been suggested that tooth resorption may be caused by

diffusion of the bleaching chemicals through dentinal tubules to the periodontal ligament.

Whether a trauma history increases the risk of tooth resorption is debated in the literature.

Root resorption may be halted if detected early57, but if left unnoticed or untreated it can

lead to loss of the tooth. Therefore, it is recommended that a close radiographic and

clinical follow-up of internally bleached teeth takes place to enable early detection of

resorption49 57.

A possible adverse effect of bleaching is a negative influence on restorative materials and

restorations, although this has not been clinically substantiated. A recent systematic

review58 concluded that there is a body of evidence from in vitro studies demonstrating that

bleaching therapies may have a negative effect on physical properties, marginal integrity,

enamel and dentin bond strength, and colour of restorative materials. However, in the

absence of clinical in vivo reports describing this adverse effect, the clinical relevance of in

vitro observations is unknown.

7.2.4 Indications and contra-indications There were no indications or contra-indications for non-vital bleaching identified in the

reviewed studies, despite the fact that some teeth did not respond to intra-coronal

bleaching. Similarly, there was no evidence to indicate which teeth are more or less likely

to have a stable bleached colour.



7.2.5 Cost of intra-coronal bleaching The cost of one bleaching treatment ranges from $150 to $200. ACC’s contribution to the

cost of a single intra-coronal bleaching treatment is $150.

7.3 Discussion 7.3.1 Methodological Quality Study Design: The methodological design quality of the non-vital bleach studies is low by

evidence based healthcare standards because the four relevant studies were all case series.

One was designed prospectively51. None of the studies are directly comparable because of

variations in almost every aspect of the studies: patient selection criteria, number of

patients, follow-up period, and type of intervention.

Sample size and statistical analysis: Sample sizes were quite small, ranging from 21 to 86

teeth. Only one study applied statistical analysis to the results51. Although p values of

0.0001, and 0.008 were reported for ANOVA and post-hoc comparison tests (respectively)

of tooth colour change, it should be noted that the sample size was only 25. The other

studies calculated percentages.

Intervention: A range of intra-coronal bleaching techniques were used in the four studies.

None of the studies used the current recommended bleach recipe of sodium perborate

mixed with either water or low concentration hydrogen peroxide. Two studies employed

only the walking bleach technique using sodium perborate and 30% hydrogen peroxide.

One study employed thermocatalytic bleaching using 35% hydrogen peroxide, and one

study used 30% hydrogen peroxide in three methods: walking bleach, thermocatalytic, and

a combination of those methods.

Comment from Referee 1: The use of 3% hydrogen peroxide is a relatively recent recommendation. As you noted, for this reason the most commonly used concentration of hydrogen peroxide for non-vital bleaching is 30 to 35% as reported in the literature.

Study population, inclusion and exclusion criteria: All study participants had

endodontically treated, discoloured anterior teeth. The trauma history of study

participants was stated in two studies, including one whose entire patient sample had lost

tooth vitality due to trauma49. The age of study participants was not well described; one

study did not state age50, the study consisting of all trauma cases described patients as

being children and adolescents49, one study included patients aged >18 yrs51, and one

reported a range of 15-57 yrs48. The exclusion of teeth with severe internal and external



discolouration due to tetracycline stains, or fluorosis was explicitly stated in only one

study.

Follow-up and study period: The follow-up period of bleach studies was relatively short,

ranging from 1 to 8 years.

Outcome measures: Three outcomes related to the effectiveness of tooth bleaching were

reported; these were patient satisfaction, success/failure and colour stability.

7.3.2 Clinical Outcomes Intra-coronal bleaching of discoloured non-vital teeth is effective in at least 60% of teeth,

as measured over the short-term. Success in three studies, as judged by dentists, ranged

from 66.2 – 79%48-50. One study showed that the dentist judged far more critically than the

patient, with success according to the patient being 91.9%, compared with 66.2% success

according to the dentist48. Another study reported a patient satisfaction of just 62%49.

The colour change is not stable in all teeth; Deliperi & Bardwell (2005)51 and Waterhouse

& Nunn (1996)49 demonstrated a stable colour change in 48% and 83% of teeth

respectively. The majority of cases of re-discolouration involved minor colour changes of

1 or 2 shades51, and none of the re-discoloured teeth returned to their original shade49 51.

The long-term stability of the bleach induced colour change is unknown.

7.3.3 Safety and adverse effects Intracoronal bleaching is associated with external tooth resorption. One of the four studies

reported a 6.9% incidence of external tooth resorption50. The consensus opinion in review

literature is that high concentrations of hydrogen peroxide should be avoided, particularly

in combination with heat.

7.3.4 Implications for outcomes over a lifetime Teeth with unstable bleached tooth colour may need retreatment to restore acceptable

aesthetics to the tooth. Intra-coronal bleaching of non-vital teeth would appear not to

place limitations on future retreatment options

7.4 Summary of Evidence There is low quality evidence from case series’ to suggest that discoloured non-vital teeth

can be whitened satisfactorily in at least 60% of cases, using high percentage hydrogen




peroxide in intra-coronal bleaching techniques. There is currently no evidence base that

describes the effectiveness of the currently recommended method that uses low

concentrations of hydrogen peroxide.

There was evidence from one of the studies that the use of high concentrations of

hydrogen peroxide is associated with external tooth resorption. The review literature

supports the use of low concentrations of hydrogen peroxide, and avoidance of heat if high

concentrations are used.

7.5 Conclusions Intra-coronal bleaching appears to be effective in the short term for a significant

proportion of discoloured non-vital teeth; but not all teeth are aesthetically restored by

this method. There is sufficient evidence to suggest that patients of any age with

discoloured non-vital secondary teeth are good candidates for receiving this treatment.

However, there is insufficient evidence to enable a description of contraindications for this

treatment.


7.6 Appendix 4: Evidence Tables for Intracoronal bleaching Evidence Based Healthcare Table Intracoronal bleaching Reference: Glockner et al 199948 Bibliographic Number: Design Description


Description: Patients who had received ‘walking internal bleaching’ were invited to have a follow-up examination. Patients were classified according to the indication: ideal = an anterior tooth with only one palatal endodontic opening borderline = included teeth with extensive proximal composite restorations that involved a large part of the tooth structure that are difficult to bleach.

Outcome Measures: Subjective observations of a) the patient and b) the dentist. Successful grades: 1=optimal 2=very good 3=good Failure grades: 4=better than before treatment 5=identical to before treatment

No. in Group: 86 patients. Number of teeth not stated, but all were anterior Age: 15-57 yrs

Inclusions: Pre-requisites for treatment were 1) careful root canal treatment 2) a radiograph to ensure no cervical defect 3) coronal sealing of root canal 4) for those with silver point root canal treatments, the silver was

removed and replaced with gutta percha. Exclusions: Not stated

Results: Overall: 66.2% success rate according to dentists 91.9% according to patients Combining scores from patients and dentists 55.2% success rate for borderline cases 91.3% success rate for ideal cases Conclusions: 1. The dentist judges far more critically than the patient 2. A high percentage of success was possible after 5 yrs when only ideal clinical indications were treated.


Selection Notes:

Walking internal bleaching using a mixture of sodium perborate (tetrahydrate) and 30% hydrogen peroxide. Treatments lasted one week, and were terminated with neutralizing calcium hydroxide for at least 7 days. Some patients received multiple treatments, until desired results were achieved. Average follow-up was 57.9 months (4.8 yrs).




Evidence Based Healthcare Table Intracoronal Bleaching Reference: Waterhouse & Nunn 199649 Bibliographic Number: Design Description


Description: Children and adolescents with endodontically treated discoloured permanent anterior teeth. All patients had lost tooth vitality due to an earlier traumatic episode 97% of teeth were classified as gray, reddish gray or off-guide.

Outcome Measures: Follow-up occurred at 6 month intervals for 18 months Colour change according to a Vita porcelain shade guide. Rediscolouration = if shade has changed by more than one unit Root resorption assessed by periapical radiograph

No. in Group: 21 central incisor teeth Mean Age: children and adolescents

Inclusions: Teeth that exhibited well-condensed gutta-percha restorations and were clinically and radiographically healthy


Results: The number of gray, reddish gray or off-guide teeth had decreased from 97% to 57% 62% of patients satisfied 83% displayed stability of shade; 17% showed some re-discoloration, but never matched original discolouration 29% failed (were veneered, or colour unchanged) No evidence of cervical or progressive apical resorption

A case series, presumed to be retrospective.

Selection Notes:

Walking bleach technique; a thick crystalline paste made with sodium perborate granules/30% hydrogen peroxide solution was sealed within the tooth. The chamber was sealed with glass-ionomer cement material. Patient was asked to return 1 to 2 weeks later. The bleaching procedure was repeated up to 10 times if improvement in colour was visible. After bleaching the tooth was restored with white gutta percha and resin composite filling.




Evidence Based Healthcare Table Intracoronal Bleaching Reference: Friedman et al 198850 Bibliographic Number: Design Description


Description: The records of 64 pulpless teeth which had been bleached were pooled and the patients were recalled for follow-up examination. 38% had suffered a trauma at some time.

Outcome Measures: Follow up occurred 1-8 yrs after bleaching occured Color assessment:

A) ‘Absolutely satisfactory’ = matching the adjacent teeth

B) ‘Clinically acceptable’ = some discoloration but acceptable to the patient

C) ‘Failed’ = discoloration, requiring further treatment

Radiographic assessment of roots to assess external tooth resorption

No. in Group: 58 pulpless anterior teeth Mean Age: not stated

Inclusions: Patients who had received intracoronal bleaching of their pulpless teeth.


Results: Colour 50% were absolutely satisfactory 29% were clinically acceptable 21% failed Root resorption 6.9% (4 teeth) had external root resorption

A retrospective case series.

Selection Notes:

Intracoronal bleaching with 30% hydrogen peroxide (Superoxol) via walking bleach method. Thermocatalytic bleaching was performed on some teeth. 35% had walking bleach 22% had thermocatalytic 43% had both 74% had one treatment 9% had 2 treatments 17% had 3 treatments All teeth were restored after bleaching with composite filling materials





Evidence Based Healthcare Table Intracoronal Bleaching Reference: Deliperi & Bardwell 200551 Bibliographic Number: Design Description


Description: Patients were 18 yrs or over

Outcome Measures: 1. Tooth colour stability during follow-up period(number of shade changes): Alpha = no change Bravo = change of colour up to 4 shades Charlie = change of colour up to 8 shades Delta = change of colour >8 shades. Tooth shades were assigned according to a Vita shade guide. 2. Shade values (1 to 16) and percentage change from baseline. Follow-up periods: 14 days after at-home bleaching was completed, then at 6 month recalls for 2 years.


Inclusions: Pulpless anterior teeth endodontically treated at least 2 yrs prior, with A3 or darker shades. Only teeth having a combination of endodontic access and Class III/IV cavities were included in the study.

Exclusions: Severe internal and external discoloration (tetracycline stains, fluorosis), smokers & pregnant & nursing women. Teeth having previous bleach treatments, and with a complete loss of clinical crown; teeth having endodontic access opening only to be restored.

Results: Colour change: all teeth improved by at least 8 vita shade values. Colour stability (2 yrs): scored “Bravo”. 12/25 teeth had no shade rebound 13/25 teeth had a shade rebound to a darker shade of up to 4 shades. 9 of these 13 had a shade rebound of only 1 or 2 shades. Shade values: Baseline mean = 14.4 (+/- 1.9) 2 wk follow up = 1.6 (+/- 0.7) 2 yr follow up = 2.8 (+/- 1.7) [2 weeks after treatment 89% change from baseline 2 yrs after treatment: 81% change from baseline There was a significant shade change between 2 wk and 2 yr follow-up, p=0.008. It is not clear what these are %’s of]

A prospective case series

Selection Notes:

In-office bleaching 35% hydrogen peroxide gel inside the pulp chamber and on the facial enamel for 30 minutes; followed with at-home bleaching using custom tray and 10% carbamide peroxide according to the inside/outside bleaching technique. At-home bleaching treatment period not stated.

Methodological Score: 3 Well reported.


8 Limitations of the review The findings of this evidence based review are considerably limited by the paucity of good

quality, long-term clinical studies, and a lack of indications and contraindications for

treatments. As a result this review was not able to establish comprehensive patient

selection criteria for each of the four treatments reviewed. The development of such

criteria will rely heavily on the consensus opinion of dental experts who convene during

the guideline development process.

The review excluded in vitro studies, and so has not accessed a source of information that

contributes to the development to current best practise in dentistry.

Similarly, the review included studies published in English only; it is known that there are

some studies published in German that may have met other inclusion criteria for this

review.

A considerable limitation of this review is that many of the studies report technology and

techniques that are out of date, e.g. all the bleaching studies used bleach solutions that are

no longer considered best practise; most of the composite resin studies used early

generation dentine bonding agents which are now obsolete; and with the release of late

generation dentine bonding agents, presumably advancements have been made in the

bonding of porcelain veneers and crowns.

Comment from Referee 1: While there have been various generations of resin bonding systems, currently the 4th generation is still considered the gold standard which has been available since the 1980s.



9 Recommendations There is insufficient evidence to make recommendations about which treatments are the

most appropriate for specific types of fracture and extent of tooth avulsion.

However, the guideline development panel should consider incorporating the following

recommendations into the guidelines. These recommendations arise from a synthesis of

all the evidence presented about survival of tooth restorations, and patient risk factors.

They also incorporate the philosophies of striving for conservation of tooth tissue, and

choosing a treatment plan that maximises the life-time potential of teeth.

1. When the primary indication for restorative treatment of fractured, non-vital

anterior teeth is discolouration, intra-coronal bleaching should be the first

treatment choice because it is effective in at least 60% of cases, has only one

harmful side effect of low incidence, and does not limit subsequent treatment

choices.

2. Unless indicated otherwise, patients <30 yrs should be treated conservatively with

composite resin build-up, or reattachment of the avulsed fragment if available.

This would be done with a clear understanding that these restorations are likely to

require replacement within 7 yrs, but that this can be done at least once before the

less conservative treatments of veneers and/or crowns need be considered.

3. In cases where either veneer or crowns are indicated, a veneer should be the first

treatment choice for the following reasons:

the survival rate of veneers appears to be better than for crowns.

a high percentage of failures are repairable, further extending the life of the

restoration.

there is greater conservation of tooth tissue, and consequently a retention of

some options for future treatments if the veneer fails.

4. Veneers should not be applied to teeth with large amounts of lost tooth tissue.

The definition of ‘large amounts’ remains to be decided.

5. A relative contraindication for veneers is poor oral health and a high caries rate.



Comments from Referee 1:

The review was accurate. This review appears to be completely based on the papers that satisfied the inclusion criteria. I consider that the report was balanced and fair and correctly interpreted the literature reviewed. Based on the evidence provided, the conclusions in this report appear to be appropriate. I appreciate your concern that there is relatively little high quality evidence on which to make recommendations about which treatments are most appropriate for certain types of tooth fracture. This particularly relates to sample size in the publication included in this review. This also makes it difficult to establish guidelines for patient and/or tooth selection criteria for each of the four treatments reviewed, however the literature for these four treatments across the range of the evidence hierarchy do report relatively similar findings. For this reason, I believe that this evidence review will be a valuable document that will be of great assistance in supporting the guideline development panel to establish restoration guidelines for fractured anterior teeth for ACC.

Comments from Referee 2:

Because of the low quality of the available research, making evidenced-based recommendations is difficult. This has been clearly identified in Section 8. The conclusions outlined in Section 9 represent a conservative approach to both the interpretation of the evidence and patient management. They are in my view consistent with what we know from the literature and what many experts would regard as best practise. The report is likely to be of significant assistance to an expert panel developing practise guidelines. The panel should be in a position to make progress with the development of a consensus-based expert opinion confident that there is no significant information of which they are not aware, avoiding the need to spent time identifying and debating the value of individual studies.



10 References 1. Burke FJ, Lucarotti PSK. Ten year outcome of crowns placed within the general dental

services in England and Wales. Journal of Dentistry 2008;doi:101.1016/j.jdent.2008.03.017.

2. Lucarotti PSK, Holder RL, Burke FJ. Analysis of an administrative database of half a million restorations over 11 years. Journal of Dentistry 2005;33:791-803.

3. Walton TR. A ten-year longitudinal study of fixed prosthodontics: 1. Protocol and patient profile. International Journal of Prosthodontics 1997;10(4):325-31.

4. Walton TR. A 10-year longitudinal study of fixed prosthodontics: clinical characteristics and outcome of single-unit metal-ceramic crowns. International Journal of Prosthodontics 1999;12(6):519-26.

5. De Backer H, Van Maele G, De Moor N, Van den Berghe L, De Boever J. An 18-year retrospective survival study of full crowns with or without posts. International Journal of Prosthodontics 2006;19(2):136-42.

6. Etemadi S, Smales RJ. Survival of resin-bonded porcelain veneer crowns placed with and without metal reinforcement. Journal of Dentistry 2006;34(2):139-45.

7. Walter MH, Wolf BH, Wolf AE, Boening KW. Six-year clinical performance of all-ceramic crowns with alumina cores. International Journal of Prosthodontics 2006;19(2):162-3.

8. Oden A, Andersson M, Krystek-Ondracek I, Magnusson D. Five-year clinical evaluation of Procera AllCeram crowns. Journal of Prosthetic Dentistry 1998;80(4):450-6.

9. Fradeani M, Redemagni M. An 11-year clinical evaluation of leucite-reinforced glass-ceramic crowns: a retrospective study. Quintessence International 2002;33(7):503-10.

10. Erpenstein H, Borchard R, Kerschbaum T. Long-term clinical results of galvano-ceramic and glass-ceramic individual crowns. Journal of Prosthetic Dentistry 2000;83(5):530-4.

11. Sjogren G, Lantto R, Tillberg A. Clinical evaluation of all-ceramic crowns (Dicor) in general practice. Journal of Prosthetic Dentistry 1999;81(3):277-84.

12. Malament KA, Socransky SS. Survival of Dicor glass-ceramic dental restorations over 14 years: Part I. Survival of Dicor complete coverage restorations and effect of internal surface acid etching, tooth position, gender, and age. Journal of Prosthetic Dentistry. 1999;81(1):23-32.

13. Takeda T, Ishigami K, Shimada A, Ohki K. A study of discoloration of the gingiva by artificial crowns. International Journal of Prosthodontics 1996;9(2):197-202.

14. Koke U, Sander C, Heinecke A, Muller H. A possible influence of gingival dimensions on attachment loss and gingival recession following placement of artificial crowns. International Journal of Periodontics & Restorative Dentistry 2003;23(5):438-45.

15. Odman P, Andersson B. Procera AllCeram crowns followed for 5 to 10.5 years: a prospective clinical study. International Journal of Prosthodontics. 2001;14(6):504-9.

16. Sakai T, Sakai H, Hashimoto N, Hirayasu R. Gingival pigmentation beneath a metallic crown: light and electron microscopic observations and energy dispersive X-ray analysis. Journal of Oral Pathology 1988;17(8):409-15.

17. Gordon S. Foreign body gingivitis associated with a new crown: EDX analysis and review of the literature.[erratum appears in Oper Dent 2000 Sep-Oct;25(5):455]. Operative Dentistry 2000;25(4):344-8.

18. Saunders WP, Saunders EM. Prevalence of periradicular periodontitis associated with crowned teeth in an adult Scottish subpopulation.[see comment]. British Dental Journal 1998;185(3):137-40.



19. Zoellner A, Heuermann M, Weber HP, Gaengler P. Secondary caries in crowned teeth: correlation of clinical and radiographic findings. Journal of Prosthetic Dentistry 2002;88(3):314-9.

20. Wilson NA, Whitehead SA, Mjor IA, Wilson NH. Reasons for the placement and replacement of crowns in general dental practice. Primary Dental Care 2003;10(2):53-9.

21. Bruce GJ, Hall WB. Nickel hypersensitivity-related periodontitis. Compendium of Continuing Education in Dentistry 1995;16(2):178, quiz 186.

22. Jackson CR, Skidmore AE, Rice RT. Pulpal evaluation of teeth restored with fixed prostheses. Journal of Prosthetic Dentistry 1992;67(3):323-5.

23. Cheung GS. A preliminary investigation into the longevity and causes of failure of single unit extracoronal restorations. Journal of Dentistry 1991;19(3):160-3.

24. Fradeani M, D'Amelio M, Redemagni M, Corrado M. Five-year follow-up with Procera all-ceramic crowns. Quintessence International. 2005;36(2):105-13.

25. Horn HR. Porcelain laminate veneers bonded to etched enamel. Dent Clin North Am 1983;27:671-684.

26. Calamia JR. Etched porcelain veneers: the current state of the art. Quintessence International. 1985;16(1):5-12.

27. Burke FJ, Lucarotti PSK. Ten year outcome of porcelain laminate veneers placed within the genral dental services in England and Wales. Journal of Dentistry 2008;doi:10.1016/j.jdent.2008.03.016.

28. Fradeani M, Redemagni M, Corrado M. Porcelain laminate veneers: 6- to 12-year clinical evaluation--a retrospective study. International Journal of Periodontics & Restorative Dentistry 2005;25(1):9-17.

29. Smales RJ, Etemadi S. Long-term survival of porcelain laminate veneers using two preparation designs: a retrospective study. International Journal of Prosthodontics 2004;17(3):323-6.

30. Peumans M, De Munck J, Fieuws S, Lambrechts P, Vanherle G, Van Meerbeek B. A prospective ten-year clinical trial of porcelain veneers. Journal of Adhesive Dentistry 2004;6(1):65-76.

31. Aristidis GA, Dimitra B. Five-year clinical performance of porcelain laminate veneers. Quintessence International 2002;33(3):185-9.

32. Sieweke M, Salomon-Sieweke U, Zofel P, Stachniss V. Longevity of oroincisal ceramic veneers on canines--a retrospective study. Journal of Adhesive Dentistry 2000;2(3):229-34.

33. Dumfahrt H, Schaffer H. Porcelain laminate veneers. A retrospective evaluation after 1 to 10 years of service: Part II--Clinical results. International Journal of Prosthodontics. 2000;13(1):9-18.

34. Walls AW. The use of adhesively retained all-porcelain veneers during the management of fractured and worn anterior teeth: Part 2. Clinical results after 5 years of follow-up. British Dental Journal 1995;178(9):337-40.

35. Calamia JR. Clinical evaluation of etched porcelain veneers. American Journal of Dentistry 1989;2(1):9-15.

36. Dumfahrt H. Porcelain laminate veneers. A retrospective evaluation after 1 to 10 years of service: Part I--Clinical procedure. International Journal of Prosthodontics. 1999;12(6):505-13.

37. Mader C. Restoration of a fractured anterior tooth. Journal of the American Dental Association 1978;96(1):113-115.

38. Tennery TN. The fractured tooth reunited using the acid-etch bonding technique. Texas Dental Journal 1978;96(8):16-17.

39. Reis A, Loguercio AD. Tooth fragment reattachment: current treatment concepts. Practical Procedures & Aesthetic Dentistry: Ppad 2004;16(10):739-40.



40. Spinas E. Longevity of composite restorations of traumatically injured teeth. American Journal of Dentistry 2004;17(6):407-11.

41. Garcia-Ballesta C, Perez-Lajarin L, Cortes-Lillo O, Chiva-Garcia F. Clinical evaluation of bonding techniques in crown fractures. Journal of Clinical Pediatric Dentistry 2001;25(3):195-7.

42. Cavalleri G, Zerman N. Traumatic crown fractures in permanent incisors with immature roots: A follow-up study. Endodontics & Dental Traumatology 1995;11(6):294-296.

43. Andreasen FM, Noren JG, Andreasen JO, Engelhardtsen S, Lindh-Stromberg U. Long-term survival of fragment bonding in the treatment of fractured crowns: a multicenter clinical study. Quintessence International 1995;26(10):669-81.

44. Andreasen JO, Andreasen FM, editors. Textbook and color atlas of traumatic injuries to the teeth. 3rd ed. Copenhagen: Munksgaard, 1994.

45. Harlan AW. The removal of stains caused by administration of medicinal agents and the bleaching of pulpless teeth. American Dental Science 1884;18:521.

46. Attin T, Paque F, Ajam F, Lennon AM. Review of the current status of tooth whitening with the walking bleach technique. International Endodontic Journal 2003;36(5):313-29.

47. Dahl JE, Pallesen U. Bleaching of the Discolored Traumatized Tooth, Chapter 33. In: Andreasen J, Andreasen F, Andersson L, editors. Textbook and Color Atlas of Traumatic Injuries to the Teeth. 4th ed: Blackwell Munksgaard, 2007:852-860.

48. Glockner K, Hulla H, Ebeleseder K, Stadtler P. Five-year follow-up of internal bleaching. Brazilian Dental Journal 1999;10(2):105-110.

49. Waterhouse PJ, Nunn JH. Intracoronal bleaching of nonvital teeth in children and adolescents: interim results. Quintessence International 1996;27(7):447-53.

50. Friedman S, Rotstein I, Libfeld H, Stabholz A, Heling I. Incidence of external root resorption and esthetic results in 58 bleached pulpless teeth. Endodontics & Dental Traumatology 1988;4(1):23-6.

51. Deliperi S, Bardwell DN. Two-year clinical evaluation of nonvital tooth whitening and resin composite restorations. Journal of Esthetic & Restorative Dentistry: Official Publication of the American Academy of Esthetic Dentistry 2005;17(6):369-78; discussion 379.

52. Heithersay GS, Dahlstrom SW, Marin PD. Incidence of invasive cervical resorption in bleached root-filled teeth. Australian Dental Journal 1994;39(2):82-7.

53. Haywood VB. History, safety, and effectiveness of current bleaching techniques and applications of the nightguard vital bleaching technique. Quintessence International 1992;23(7):471-88.

54. MacIsaac AM, Hoen CM. Intracoronal bleaching: concerns and considerations. Journal (Canadian Dental Association) 1994;60(1):57-64.

55. Dahl JE, Pallesen U. Tooth bleaching--a critical review of the biological aspects. Critical Reviews in Oral Biology & Medicine 2003;14(4):292-304.

56. Tredwin CJ, Naik S, Lewis NJ, Scully C. Hydrogen peroxide tooth-whitening (bleaching) products: review of adverse effects and safety issues. British Dental Journal 2006;200(7):371-6.

57. Friedman S. Internal bleaching: long-term outcomes and complications. Journal of the American Dental Association 1997;128 Suppl:51S-55S.

58. Attin T, Hannig C, Wiegand A, Attin R. Effect of bleaching on restorative materials and restorations--a systematic review. Dental Materials 2004;20(9):852-61.





Appendix 1: Evidence tables for Crowns (go to p 33)

Appendix 2: Evidence tables for Veneers (go to p 56)

Appendix 3: Evidence tables for Composite resin restorations (go to p 74)

Appendix 4: Evidence tables for Intracoronal bleaching (go to p 86)




Appendix 5. Level of evidence in the SIGN system

1++ High quality meta analyses, systematic reviews of RCTs, or RCTs with a very low risk of bias

1+ Well conducted meta analyses, systematic reviews, or RCTs with a low risk of bias

1- Meta analyses, systematic reviews, or RCTs with a high risk of bias

2++ High quality systematic reviews of case-control or cohort studies

High quality case-control or cohort studies with a very low risk of confounding or bias and a high probability that the relationship is causal

2+ Well conducted case control or cohort studies with a low risk of confounding or bias and a moderate probability that the relationship is causal

2- Case control or cohort studies with a high risk of confounding or bias and a significant risk that the relationship is not causal

3 Non-analytic studies, e.g. case reports, case series

4 Expert opinion


Appendix 6. Studies excluded from this review

Study

Title Reasons for excluding

Crown Studies Akkayan & Caniklioglu 1998

Resistance to fracture of crowned teeth restored with different post systems. European Journal of Prosthodontics & Restorative Dentistry 1998;6(1):13-8.

An in vitro study

Aquilino & Caplan 2002

Relationship between crown placement and the survival of endodontically treated teeth. Journal of Prosthetic Dentistry 2002;87(3):256-63.

Can not differentiate data for anterior teeth

Ellner et al 2003 Four post-and-core combinations as abutments for fixed single crowns: a prospective up to 10-year study. International Journal of Prosthodontics 2003;16(3):249-54.


Felden et al 1998 Retrospective clinical investigation and survival analysis on ceramic inlays and partial ceramic crowns: results up to 7 years. Clinical Oral Investigations 1998;2(4):161-7.

Posterior teeth

Goodacre et al 2001

Tooth preparations for complete crowns: an art form based on scientific principles. Journal of Prosthetic Dentistry 2001;85(4):363-76.

Does not report outcomes

Jackson et al 2006 Factors affecting treatment outcomes following complicated crown fractures managed in primary and secondary care. Dental Traumatology 2006;22(4):179-185.

Outside scope. About pulp treatment, not restorative treatment

Jensen et al 1990 Plaque retention on Dicor crowns and gingival health evaluated over a 4-year period. International Journal of Periodontics & Restorative Dentistry. 1990;10(6):454-63.

Posterior teeth

Karlsson et al 1992 A clinical evaluation of ceramic laminate veneers. International Journal of Prosthodontics. 1992;5(5):447-51.

Follow-up less than 5 years

Lewis & Smith 1988

A clinical survey of failed post retained crowns. British Dental Journal. 1988;165(3):95-7.

Tooth position not stated



Kelly & Smales 2004

Long-term cost-effectiveness of single indirect restorations in selected dental practices. British Dental Journal. 2004;196(10):639-43; discussion 627.

Cannot differentiate data for anterior teeth


Survival of Dicor glass-ceramic dental restorations over 14 years. Part II: effect of thickness of Dicor material and design of tooth preparation. Journal of Prosthetic Dentistry. 1999;81(6):662-7.

Outside scope; Not relevant to EBH question


Survival of Dicor glass-ceramic dental restorations over 16 years. Part III: effect of luting agent and tooth or tooth-substitute core structure. Journal of Prosthetic Dentistry. 2001;86(5):511-9.

Outside scope; Not relevant to EBH question

Miyamoto et al 2007

Treatment history of teeth in relation to the longevity of the teeth and their restorations: outcomes of teeth treated and maintained for 15 years. Journal of Prosthetic Dentistry 2007;97(3):150-6.


Moopnar & Faulkner 1991

Accidental damage to teeth adjacent to crown-prepared abutment teeth. Australian Dental Journal 1991;36(2):136-40.

Adverse effect not relevant to the EBH question

Ozcan & Niedermeier 2002

Clinical study on the reasons for and location of failures of metal-ceramic restorations and survival of repairs. International Journal of Prosthodontics 2002;15(3):299-302.

Can not differentiate between crown data and fixed partial denture data

Palmqvist & Swartz 1993

Artificial crowns and fixed partial dentures 18 to 23 years after placement. International Journal of Prosthodontics. 1993;6(3):279-85.

Can not differentiate between fixed partial dentures and crowns

Pippin et al 1995 Clinical evaluation of restored maxillary incisors: veneers vs. PFM crowns. Journal of the American Dental Association 1995;126(11):1523-9.


Reitemeier et al 2006

Metal-ceramic failure in noble metal crowns: 7-year results of a prospective clinical trial in private practices. International Journal of Prosthodontics 2006;19(4):397-9.

No anterior teeth data

Scherrer et al 2001 Incidence of fractures and lifetime predictions of all-ceramic crown systems using censored data. American Journal of Dentistry. 2001;14(2):72-80.


Segal 2001 Retrospective assessment of 546 all-ceramic anterior and posterior crowns in a general practice. Journal of Prosthetic Dentistry 2001;85(6):544-50.

Can not differentiate follow-up period for anterior teeth

Sjogren et al 1999 Clinical examination of leucite-reinforced glass-ceramic crowns (Empress) in general practice: a retrospective study. International Journal of Prosthodontics




1999;12(2):122-8.

Spiechowicz et al 1999

A long-term follow-up of allergy to nickel among fixed prostheses wearers. European Journal of Prosthodontics & Restorative Dentistry 1999;7(2):41-4.

Can not differentiate the crown data

Thayer et al 1993 Acid-etched, resin bonded cast metal prostheses: a retrospective study of 5- to 15-year-old restorations. International Journal of Prosthodontics 1993;6(3):264-9.

Not about single crowns; Fixed Partial Denture

Tiwarri et al 1992 Effects of restorations and carious lesions on the periodontium in humans. Annals of Dentistry 1992;51(2):22-5.

Does not report N for crown group.

Valderhaug et al 1997

Assessment of the periapical and clinical status of crowned teeth over 25 years. Journal of Dentistry. 1997;25(2):97-105.


Wagenberg et al 1989

Exposing adequate tooth structure for restorative dentistry. International Journal of Periodontics & Restorative Dentistry 1989;9(5):322-31.

Not relevant. Related to tooth lengthening procedure

Wagner et al 2003 Long-term clinical performance and longevity of gold alloy vs ceramic partial crowns. Clinical Oral Investigations 2003;7(2):80-5.

Posterior teeth

Wasserman et al 2006

Clinical long-term results of VITA In-Ceram Classic crowns and fixed partial dentures: A systematic literature review. International Journal of Prosthodontics 2006;19(4):355-63.

No anterior tooth data

Wolfart et al 2004 Comparison of using calcium hydroxide or a dentine primer for reducing dentinal pain following crown preparation: a randomized clinical trial with an observation time up to 30 months. Journal of Oral Rehabilitation 2004;31(4):344-50.

Adverse effect not relevant to the EBH question

Zitzmann et al 2007

Clinical evaluation of Procera AllCeram crowns in the anterior and posterior regions. International Journal of Prosthodontics 2007;20(3):239-41.


Veneer studies Reason for exclusion Belcheva 2001 Esthetic restoration of traumatized permanent teeth in children using composite

vestibular veneers (preliminary communication). Folia Medica (Plovdiv) 2001;43(1-2):9-11.


Kourkouta et al 1994

The effect of porcelain laminate veneers on gingival health and bacterial plaque characteristics. Journal of Clinical Periodontology 1994;21(9):638-40.

Follow-up period not cited; small sample size



Reid et al 1991 Gingival health associated with porcelain veneers on maxillary incisors. International Journal of Paediatric Dentistry 1991;1(3):137-41.

Follow-up period less than 4 years

Friedman 1998 A 15-year review of porcelain veneer failure--a clinician's observations. Compendium of Continuing Education in Dentistry. 1998;19(6):625-8.

A commentary; Inadequate reporting of methods, inclusion, and outcome data.

Meijering et al 1997

Patients' satisfaction with different types of veneer restorations. Journal of Dentistry 1997;25(6):493-7.


Meijering et al 1997

Recognition of veneer restorations by dentists and beautician students. Journal of Oral Rehabilitation 1997;24(7):506-511.


Kreulen et al 1998 Meta-analysis of anterior veneer restorations in clinical studies. Journal of Dentistry 1998;26(4):345-53.


Calamia 1989 Clinical evaluation of etched porcelain veneers. American Journal of Dentistry 1989;2(1):9-15.


Shaini et al 1997 Clinical performance of porcelain laminate veneers. A retrospective evaluation over a period of 6.5 years. Journal of Oral Rehabilitation. 1997;24(8):553-9.

Mean follow-up period not cited

Coyne & Wilson 1994

A clinical evaluation of the marginal adaptation of porcelain laminate veneers. European Journal of Prosthodontics & Restorative Dentistry. 1994;3(2):87-90.


Wakiaga et al 2004 Direct versus indirect veneer restorations for intrinsic dental stains. Cochrane Database of Systematic Reviews John Wiley & Sons, Ltd Chichester, UK 2004.


Dunne & Millar 1993

A longitudinal study of the clinical performance of porcelain veneers. British Medical Journal 1993;175:317-21.


Bleach Studies Reason for exclusion Alnazhan 1991 External Root Resorption after Bleaching - a Case-Report. Oral Surgery Oral

Medicine Oral Pathology Oral Radiology and Endodontics 1991;72(5):607-609.

The adverse effect being reported had signs of being present prior to bleach treatment

Amato et al 2006 Bleaching teeth treated endodontically: Long-term evaluation of a case series. Journal of Endodontics 2006;32(4):376-378.

Analysis is flawed. Reported ‘n’ of those followed up is incorrect.

Caughman et al 1999

Carbamide peroxide whitening of nonvital single discolored teeth: case reports. Quintessence International 1999;30(3):155-61, 213-4.

No follow-up Outcome measures not clearly defined



Dahlstrom et al 1997

Hydroxyl radical activity in thermo-catalytically bleached root-filled teeth. Endodontics & Dental Traumatology 1997;13(3):119-25.

An in vitro study

Feiglin 1987 A 6-year recall study of clinically chemically bleached teeth. Oral Surgery, Oral Medicine, Oral Pathology 1987;63:610-3.

Position of teeth not stated Outcome measure not adequate

Frazier 1998 Nightguard bleaching to lighten a restored, nonvital discoloured tooth. Compendium 1998;19(8):810-813.

No follow-up

Haywood et al 1994

Effectiveness, side effects and long-term status of nightguard vital bleaching. Journal of the American Dental Association 1994;125(9):1219-26.

Position of teeth not stated Outcome measure not adequate

McCaslin et al 1999

Assessing dentin color changes from nightguard vital bleaching. Journal of the American Dental Association 1999;130(10):1485-90.

An in vitro study

Poyser et al 2004 Managing discoloured non-vital teeth: the inside/outside bleaching technique. Dental Update 2004;31(4):204-10.

Not relevant; about methodology/technique

Turkun & Turkun 2004

Effect of nonvital bleaching with 10% carbamide peroxide on sealing ability of resin composite restorations. International Endodontic Journal 2004;37(1):52-60.

An in vitro study

Composite Resin Studies

Reason for exclusion

Redman et al 2003 The survival and clinical performance of resin-based composite restorations used to treat localised anterior tooth wear. British Dental Journal 2003;194:566-572.

Not fractured teeth

Salvi et al 2007 Clinical evaluation of root filled teeth restored with or without post-and-core systems in a specialist practice setting. International Endodontic Journal 2007;40(3):209-15.

Outside scope of EBH Question. Not fractured teeth, a study of root-filled teeth.

Creugars et al 2005

5-year follow-up of a prospective clinical study on various types of core restorations. International Journal of Prosthodontics 2005;18(1):34-9.

Outside scope of EBH Question. Not fractured teeth, a study of root-filled teeth.

Creugars et al 2005

A 5-year prospective clinical study on core restorations without covering crowns. International Journal of Prosthodontics 2005;18(1):40-1.

An expanded abstract. Outside scope of EBH Question. Not fractured teeth, a study of root-filled teeth.

Martens et al 1988 Reattachment of the original fragment after vertical crown. The Journal of Pedodontics 1988;13:53-62.

No follow-up described.



Smales 1991 Effects of enamel-bonding, type of restoration, patient age and operator on the

longevity of an anterior composite resin. Am J Dent 4(3):130-3 1991;4(3):130-3.

Not trauma population

Peumans et al 1998

The influence of direct composite additions for the correction of tooth form and/or position on periodontal health. A retrospective study. Journal of Periodontology 1998;69(4):422-7.

Not trauma population

Ehrmann 1989 Restoration of a fractured incisor with exposed pulp using original tooth fragment: report of case. Journal of the American Dental Association. 1989;118(2):183-5.

Case study

Baratieri et al 1990 Tooth fracture reattachment: case reports. Quintessence International 1990;21:261-70.

Case study

Kanca 1996 Replacement of a fractured incisor fragment over pulpal exposure: a long-term case report. Quintessence International 1996;27:829-32.

Case study

Gorecka et al 2000 Direct pulp capping with a dentin adhesive resin system in children's permanent teeth after traumatic injuries: case reports. Quintessence International 2000;31(4):241-8.

Case study

Vilela Maia et al 2003

Tooth fragment reattachment: Fundamentals of the technique and two case reports. Quintessence International 2003;34(2):99-107.

Case study

Basuttil Naudi & Fung 2007

Tooth fragment reattachment after retrieval from the lower lip - a case report. Dental Traumatology 2007;23(3):177-80.

Case study

Svizero et al 2003 Partial pulpotomy and tooth reconstruction of a crown-fractured permanent incisor: A case report. Quintessence International 2003;34(10):740-747.

Case study

Shah 2007 1. Shah P. direct restoration of a discoloured single anterior tooth - A multi-layer approach. Oral Health 2007;97(4):61-64.

Case study




Documents

venee