CONTINUING EDUCATION 1

EBD AND DENTAL MATERIALS

Evidence-Based DentistryAs It Relates to Dental MaterialsStephen C. Bayne, MS, PhD; and Mark Fitzgerald, DDS, MS

LEARNING OBJECTIVES

Abstract: Evidence-based dentistry (EBD) is reviewed in depth to underscore

the limitations for evidence-based dental materials information that exist at this

time. Anecdotal estimates of evidence for dental practice are in the range of 8%

to 10%. While the process of evaluating the literature base for dentaf evidence

began 20 years ago, it was not practical to implement it until high-speed wireless

connections, open access to journals, and omnipresent connections via smart

phones became a reality. EBD includes five stages of information collection and

analysis, starting with a careful definition of a clinical question using the PICO(T)

approach. Clinical evidence in randomized control trials is considered the best.

Clinical trial perspectives (prospective, cross-sectional, retrospective) and out-

come designs (RCTs, SCTs, CCTs, cohort studies, case-control studies) are quite

varied. Aggregation techniques (including meta-analyses) allow meaningful combinations of clinical data from

trials with similar designs but with fewer rigors. Appraisals attempt to assess the entire evidence base without

bias and answer clinical questions. Varying intensities to these approaches—Cochrane Collaboration, ADA-EBD

Library, UTHSCSA CATs Library—ai-e used to answer questions. Dental materials evidence from clinical trials

is infrequent, short-term, and often not compliant with current guidelines (registration, CONSORT, PRISMA).

Reports in current evidence libraries indicate < 5% of evidence is related to restorative dental materials.

• identify the five stagesof operation in evi-dence-based dentistryused to answer a clinicalquestion

• expiain the characteris-tics of the major typesof clinical researchdesigns used to coliectevidence

•discuss why clinlcairesearch evidence forrestorative dentai mate-rials is lacking

Evidence-based care had its early political beginningswith the first appeals by Archibald Cochran' in 1972 torequire scientific justifications as part of the decision-making process. Cochran is often credited with beingthe "father" of modern evidence-based medicine. Until

that time, most medical (and dental) practice was based on tradi-tion or clinical preference rather than analysis of the informationin the published literature and consideration of patient factors.Table 1 provides a list of useful resources.

Evidence-based medicine (EBM) or dentistry (EBD) is a combina-tion of three key criteria that are the foundation for decision-making:1) best evidence; 2) clinical expertise; and 3) patient values. Thispraetice triad is logical but often misinterpreted. Clinical expertiseincludes consideration of an individual's clinical talents and personal

experiences. Patient values take into account the cultural, socioeco-nomic, and other special patient values infiuencing choices. Bestevidence for EBD is filtered from all the available evidence about theclinical question of interest. All three criteria are of equal importance.Several common misconceptions arise. Eirst is that EBD is onlyabout evidence, when, in fact, it involves all three parts of the triad.Second is the notion that identifying a publication or source of agree-ment for a given decision is sufficient evidence; however, evidenceis based on examining all available information in an unbiased andsystematic way. Third is that evidence is truth. It is not; evidence isthe collection of scientific information that is available at a specifictime, but it is typically incomplete and can be misleading.

Wliile different definitions may be cited for EBM or EBD, thetraditional one is "...the conscientious, explicit and judicious use of

18 COMPENDIUM January 2014 Volume 35, Number 1

The Current State ofAdhesive Dentistry:A Guide for Clinical Practicedentalaegis.com/go/cced521

current best evidence in making decisions about the care of individualpatients...".'' Notice again that the focus tends to be on the evidenceportion of the triad, yet all three components are equally important.

Determining how much evidence actually exists has long beendifficult. Wliat is generally accepted is that very little evidence isknown. An anecdotal estimate is that there is only about 8% to 10%evidence to support what occurs in general dental practice.*- This ispartly because good evidence usually is associated with a well-con-ducted clinical trial that has been extensively peer-reviewed and

published in a reputableRelated Content: journal. Clinical trials are

expensive, not often done,and may only cover a fewof the variables of inter-est for an issue. They alsorequire several years tocollect the answer, and

^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ * even more years for thatinformation to reach the

public domain, thereby creating a significant time lag. Thus, it isestimated that under optimal circumstances, about 50% of theevidence may be available, while the rest is in some earlier stageof investigation and discovery. This means that only about 10% ofcomplete evidence is available while 50% is needed, but it takestime to conduct the necessary clinical trials. Therefore, 10 to 15years or more may pass before a practical evidence base is available.

This process has only been initiated in recent years partly be-cause the necessary technologies are just now becoming widelyavailable (Figure 1). Also, there are many tedious steps involvedin collecting an answer that are not yet standardized. Collectingevidence is remarkably similar in stages (Figure 1) to all researchoperations of vn-iting protocols for grants or writing scientificpublications—it is "the scientific method."*" The path includes: 1)asking a clinical question; 2) collecting knowledge in the publishedliterature; 3) assessing the quantity and quality of that informa-tion; 4) weighting and/or aggregating the information; and 5)creating a conclusion or answer. Once the answer is available, itcan be published in one form or another and used to create newpublished literature. Often these answers are reported as criticalreviews or critical appraisals and collected into evidence libraries.The answers, whether involving small questions or large ones, maynot be satisfying if little published information exists. It is muchmore common for them to be included as part of a summary men-tioning that more information or investigation should be done toprovide a complete answer.

There are many challenges along the path to producing an an-swer, including vvriting a clear, well-defined clinical question. ThePICO approach can ensure that this happens.' It involves breakingapart the elinical question into four parts: P = patients, population,or problem of interest; I = intervention, treatment, or other optionfor care; C = control or comparison; O = outcome of interest. Inmany cases, there is also concern for the time period of measure-ment and a T may be added to the acronym (PICOT).* Once thequestion is well formed, a search is conducted in available bio-medical databases (eg, PUBMED, Web of Knowledge [Table 1])

www.compendiumlive.com

Resources for Evidence-Based Dentistryfor Dental Materials

Publication Databases

• PUBMED database, http://www.ncbi.nlm.nih.gov/pubmed/

• Web of Knowledge, http://apps.webofknowiedge.com/

• Googie Scholar, http://scholar.googie.com/

• EMBASE, http://embase.com/

• TRIP database, http://www.tripdatabase.com/index.html

Clinical Trials Registries

• Nationai Library of Medicine. Ciinical Trials ProtocolRegistration System, https://register.clinicaitriais.gov/

• EU Ciinicai Trials Registration System,https://www.clinicaltrialsregister.eu/

• World Health Organization, International Trials RegistryPlatform, http://apps.who.int/trialsearch/

Clinical Trial Guidelines

• CONSORT. CONsoiidated Standards Of Reporting Trials,http://www.consort-statement.org/

• PRiSMA. Rules for preferred reporting items for systematicreviews and meta-anaiyses, http://prisma-statGment.org/

Evidence-Based Dentistry Libraries

• Cochrane Collaboration, http://www.cochrane.org/

• American Dental Association EBD Library, http://ebd.ada.org/

• UTHSCSA CATS Library, https://cats.uthscsa.edu/

fíítóriait •

Center for Evidence Based Medicine, http://www.cebm.net/

Booi<s

• Geyman JP, Deyo RA, Ramsey SD. Evidence-Based ClinicalPractice - Concepts and Approaches. Boston, MA: Butterworth-Heinemann: 2000.

• Huliey SB, Cummings SR. Designing Clinical Research - AnEpidemiologie Approach. Baltimore, MD: Wiiiiams and Wilkins:1998.

Journals

• Evidence-Based Dentistry, http://www.nature.com/ebd/

• Journal of Evidence-Based Dental Practice, http://www.journais.eiseyier.com/journai-of-evidence-based-dentai-practice/

APPs

• Uniyersity of Michigan, EBD APP, http://www-personai.umich.edu/-sbayne/EBD/EBD-Web-APPhtm

January 2014 COMPENDIUM 19

CONTINUING EDUCATION 1 I EBD AND DENTAL MATERIALS

to identify information. Quantity and quality considerations areessential. Defining the quality can be quite involved, and currentlythere is no widely accepted and standardized approach for this. Ifthere were, EBD might become a fully automated process. Meta-analyses and other tools for combining information are helpful aswell, but, again, they are not uniform. Locating information to beconsidered as evidence can now be done relatively quickly com-pared to two decades ago. Today, with high-speed networks, digitallibraries, and open access, this process can occur in seconds. Thereare applications (APPs) that facilitate this (Table 1).

Evidence appears in many forms. EBM and EBD tend to focuson clinical trials. There is a great variety of evidence to consider, allof which is valuable depending on the particular stage of evidencecollection. New procedures or products often precede the clinical

Objective Materials & Methods Results Discussion

Deiays to adopting the process:

1990-2002 - 1 ) Slow networks; 2) Very few digital articles; 3) limited clinitai research

2002-2008 - 1 ) High-speed networks; 2) Mobile connections; 3) Open-access literature

2008-2012 - 1 ) More clinical research; 2) More critical reviews; 3) More rules for articles

2012-2015 - 1 ) Better articles; 2) Routine quality assessment; 3) More CATs

Fig 1. F ive s tages o f us ing ev ider ice t o answer a c l in ical ques t i on .

BEST

Aggregation

3

O

Low level Middle level High level

Level of peer review

Fig 2. Evidence map ranking information quality by level of peer review. Sources of evi-

dence can be ranked as a 1-dimensional (1-D) pyramid (not shown) or a 2-dimensional

(2-D) map. Best evidence involves clinical research information.

trial evidence desired. Early information may have little peer review,even if it is of good quality. After 1 to 2 years, more information typi-cally becomes available as early non-clinical reports are publishedand peer groups develop Delphi assessments. After 5 to 10 years, theclinical data of interest finally begins to emerge. Different clinicaltrial types or efibrts may assess different patient variables, so theinformation may continue to accumulate for several years. Figure 2is an evidence map meant to cover all of these situations. At the topright-hand corner is the best possible evidence—that is, evidencethat is highly peer-reviewed, good quality, and includes critical ap-praisals and meta-analyses. Other similar explanations of quality orconfidence in evidence use a linear scale or pyramid and deal onlywith the tnethods found in the top right-hand corner of the map. Itshould be noted, however, that all evidence on the map might have

some value at some point.

Clinical Trial TypesClinical information is collected in a variety ofways,' and those difi'erences impact the value ofthe information. Difi erent biases maybe included.Different tj jes of calculations may not be possible.Three major parameters of clinical trial designsinvolve the "timing," the "sampling method" ofthe population, and the nature of the "outcomes"being assessed. A quick summary of all types ispresented in Eigure 3. A more expansive treatiseon types is presented by Spilker.'" A trial may bedesigned as a longitudinal prospective one (toproject into the future), a cross-sectional one, ora longitudinal retrospective one. Longitudinalprospective trials allow for careful planning of allthe factors to be controlled and the informationto be collected. Retrospective ones are limited towhat might have been previously planned in a trial.Across-sectional trial audits the status or currentoutcome of patients already treated and gener-ally does not include much information about thevariables associated with that treatment. Cross-sectional studies are often dififerent from others,due to the limited qualification of the informationbeing collected. In testing the longevity of dentalmaterials, a cross-sectional trial will often reportless than half the value ofthat of prospective lon-gitudinal trials."^

Longitudinal prospective trials maybe careful-ly designed with controls and measures of manykey factors, with randomization for patient selec-tion and treatment—ie, randomized controlledtrials (RCTs). Less-well-controlled trials maysimply be referenced as controlled clinical trials,or CCTs. In dental materials testing, in lieu of con-trols, the assessment system relies on calibratedevaluators'^'^ and published standards for assess-ment. They are distinguished as standards-basedclinical trials, or SCTs.'* If patients are selected

20 COMPENDIUM January 2014 Volume 35, Number 1

Related Content:

Controlling Biofilm withEvidence-Based Dentifrices

dentalaegis.com/go/cced522

for inclusion on the basisof having a condition orrisk, the trial is a cohortstudy. If the study is fo-cused on patients whohave already displayed a

^ ^ ^ ^ ^ ^ ^ • H ^ ^ ^ ^ ^ ^ ^ ^ ^ H particular outcome of in-terest, the study is a case-

control study. Additionally, there are also some combinations ofthese qualifiers as well.

Restorative dental materials present some dis-tinctive challenges for clinical testing. A numberof additional factors' beyond the treatment orchoice of materials affect outcomes. These arecharacterized as: 1) operator factors; 2) designor preparation factors; 3) materials factors; 4)intraoral location factors; and 5) patient factors.Experience strongly hints that operator factorsdominate and may represent more than half therisk affecting the outcomes measured.

Two options exist for data collection. The firstis to employ only highly trained and calibratedclinicians following specific rules."'"Historically,this has been the case for trials managed in clini-cal research units (CRUs) of universities or insti-tutions. The alternative is to ignore those opera-tor factors and let them affect the results in orderto obseiTe outcomes that reflect typical practices.Trials managed this way involve a large number ofpractices contributing information and are calledPractice Based Research Networks (PBRNs).Both types have strengths, but information fromPBRNs is more limited in interpretation becausethe variables are not as well controlled.

Results from CRUs and PBRNs can be quitedifferent and often conflicting. For example,PBRNs allow for restoration replacement whenclinically anticipated, not necessarily because ofreal failure, while CRUs measure performanceto the point of failure. Therefore, longevitybased on PBRN performance is typically calcu-lated to be only half that of CRUs. Additionally,PBRNs report clinical assessments of secondarycaries based on uncalibrated or unconfirmedclinical judgments, which are often skewed bymisinterpretation of margin performance, andthey report secondary caries as the major reasonfor restoration failure. In contrast, CRUs reportsecondary caries as almost non-existent,'"^' andthey report restoration fracture as the majorfailure mode. It must be noted that CRUs usu-ally actively manage caries risk, use inclusioncriteria that exclude high-risk patients, and aremuch more discriminating about what changesin restoration margins connote.

Dental materials research, especially longitudinal prospective clini-cal trials of materials, historically has not been supported by majorsources of research fundingsuch as National Institutes of Health (NIH)until recently (2005), and then only as PBRNs. CRU trials have beensupported by dental companies as short-term-ie, 1 to 3 years—efforts.Thus, the base of information for evidence-based dentistry is rathersmall. TMs substantially limits the basis for making evidence-baseddecisions and also prevents efforts, such as correlating laboratoiy re-search tests and clinical outcomes, to foreshorten the research anddevelopment of new materials.

Date2015

Restrospectivelongitudinalclinical trial

Trial types:

RandomizedControlled Trials(RCTs)

StandardizedControlled Trials(SCTs)

Controlled ClinicalTrials (CCTs)

Cohort Trials

Case-controlledTriais

Cross-sectionalclinical trial

Controls:

Yes

NoUses standards

Yes

Yes

Yes

Prospectivelongitudinalclinical trial

Risk factors:

Measured

Measured

Measured

Basis of patientselection

Measured

Outcomes:

Observed

Observed

Observed

Observed

Basis of patientselection

Fig 3. Schematic summary of clinical trial types based on timing and outcomes.

in Vitro in Vivolab factors:• Operator• Design• Material• Interfaces

Environment

Direct PtObservations

(USPHS)

Clinical factors:• Operator• Design• Material• tocation• Patient

Clustered or Íweighted

observations j

Indirect Pt Obser-vations (replicasor pbotograpbs)

= Single-valued lab test ' Single intraoral observation

Fig 4. Challenges for detecting meaningful correlations between in-vivo and in-vitrotesting, (reproduced with permission from Elsevier from reference 14)

www.compendiumlive.com January 2014 COMPENDIUM 21

CONTINUING EDUCATION 1 | EBD AND DENTAL MATERIALS

Aggregation of Clinical EvidenceRarely are clinical trials large and complete enough in design thatthey can stand alone in answering a question. A number of variables,such as patient age, gender, risk factors, pre-existing conditions,socioeconomic factors, and trial design biases, are confounders.These challenges can often be managed when there are several goodtrials in existence by combining the information from the trials.There are statistical approaches such as meta-analyses^^ to weighthe quality of the trials, potentially combine the data, and forge agreater understanding of the true answer for a clinical question.An early example of applying this process to posterior compositewear results was reported by Taylor et al.- If the data cannot becombined, it is possible to systematically review-'' and aggregateresults in terms of relationships or risks (forest plots) to estimatethe true answer. Therefore, critical appraisals or meta-analyses areoften described as the "gold standard" of clinical evidence.

Anticipating the need to combine clinical trials, a set of rules hasbeen developed over the past decade or so to provide more uniformdata documentation and reporting. The first rule is that to publisha clinical trial, it must be preregistered. Different registration op-tions are possible (Table 1 list of Clinical Trials Registries), but allare public, describe the goals, report the clinical design, indicatethe data types collected, and can include information about themanagement and funding. While somewhat controversial, this

rule helps to ensure that the original design of the clinical trial isknown. Publication of clinical trial results requires that completecharacterization of the design be included. Guidelines in this re-gard are collected as CONsolidated Standards Of Reporting Trials(CONSORT [Table 1]). Guidelines for aggregating or meta-anal-yses are published as Preferred Reporting Items for Systematicreviews and Meta-Analyses (PRISMA [Table 1]). A good exampleof a clinical trial that meets the standard was published recently

While it stands to reason that everyone would like to be able tocombine their information with sufficient good clinical trials us-ing these methods, this is rarely possible. It is also the underlyingreason why evidence-based dentistry has been characterized asinvolving only 8% to 10% evidence.

Libraries of EBD InformationTo collect the evidence base, a number of approaches have beenused during the past 20 years. Of these, the foremost and mostformal one is the Cochrane Collaboration, which was created in1992 and demands good-quality clinical trial information. Sys-tematic reviews in the Cochrane Collaboration are produced byindividuals specially trained to adhere to the formal analytic pro-cedures that: 1) define a specific clinical question; 2) perform acomprehensive review to identify all possible literature; 3) follow

TABLE 2

Examples of Types of Laboratory Tests Performed on Dental Materials

Physical Properties

- Thermal (diffusivity,

conductivity, LCTE)

- Eiectricai

- Light (color, gloss,index of refraction,opacity, translucency,fluorescence, radi-opacity)

- Mass (density)

ChemicalProperties

- Chemical corrosion

- Electrochemicalcorrosion

- Absorption/adsorption

- Solubility

- Diffusion(F recharge rates)

-Shrinkageon setting

- Percent conversion

- Degree ofpolymerization

- Tm and/or Tg

- Copoiymerizationrates and Q/e

- Cross-link density

- Heats of reaction

- Residual materials

- Degradation events(depolymerization.chemical degradation,silane hydrolysis)

MechanicalProperties

- Modulus

- Elastic limit, yieldstrength

- Percent eiongation

- Ultimate strength

- Strain-rate sensitivity

- Temperaturedependence

- Bond strengths(to dentin, enamel,casting alloys, por-celain, other dentalceramics)

- Wear (two-body,three-body).attrition, abrasion,erosion, food wear.polishability,dentifrice wear

- Toughness

- Fracture resistance

- Fatigue resistance(mechanical.thermal)

BiologicalProperties

- Toxicity

- Mutagenicity

- Sensitivity

- No worrisomeingredients(eg, BPA)

(measuredat molecular.

cellular, andtissue levels)

ClinicalManipulation

- Minimal isolation

- Bulk placement

- Bulk cure

- Self cure

- Bonding

- Finishing/polishing

- Good wetting

- Low shrinkage

- Minimal recycling.waste, andpackaging

ClinicalProperties

- Caries resistance

- Color

- Surface texture

- Marginal adapta-tion

- Marginal staining

- Surface texture

- Wear resistance

- Postoperative

sensitivity

- Fracture resistance

- Retention

22 COMPENDIUM January 2014 Volume 35, Number 1

Clinical trials

require much more

time and expense

than laboratory

investigations of

properties or clinical

simulations. Only a

few laboratory

investigations have

shown correlations

with actual

clinical results.

a peer-reviewed protocol; 4) select studies forinclusion; 5) assess quality of each study; 6)synthesize the findings in an unbiased manner;and 7) interpret the findings in a balanced andimpartial summary. Almost invariably, neededRCTs, CCTs, or SCTs are non-existent at pres-ent and the conclusions of efforts are eitherthat there is no clinical evidence or its qualityis poor. As of October 2013, the Cochrane Col-laboration included 152 reports for dentistry,which primarily focused on prevention anddental sealants. Still others have collected theavailable evidence, rated its quality, and triedto force a limited answer to a clinical question.The American Dental Association (ADA) in thepast few years has made a major commitmentto collecting evidence and training practitioners(Table 1). The ADA EBD Library currently hascollected more than 2,300 references (E. Vas- ^ ^ ^ ^ ^ ^ ^ ^ ^silos. Manager, ADA Center for Evidence-BasedDentistry, personal communication, October 14,2013) that are clinical trials, meta-analyses, critical appraisals, orreferenees to Cochrane Collaboration reports. The dental schoolat the University of Texas Health Science Center at San Antonio(UTHSCSA) has approached the problem more practically,-'* iden-tifying relatively limited clinical questions, collecting two to fivereadily available reports, evaluating and rating the quality of thosereports, and providing one-page summaries with potential conclu-sions. These are called "critically appraised topics" (CATs) ' anddepend on trained faculty and students to generate them (Table 1).

One of the major benefits of each of these libraries is that theyform a new database that can be searched quickly for clinical an-swers. Rather than repeating the entire EBD process outlined inFigure 1, EBD libraries can be searched, making it possible to re-ceive the answers in seconds. At the University of Michigan, a web-based APP (Table 1) has been developed to provide quick accessfor PICO searches of the literature or EBD libraries to discoveranswers to clinical questions. More of these types of portals areanticipated in the very near future.

As with any effort to examine the literature, the evidence isusually not final, but is continuing to develop. Appraisals must beroutinely revisited; while there is no formal requirement, the rec-ommendation is often that appraisals be redone every 2 to 5 years.It is important to reiterate that evidence is not truth; it is simplythe collection of scientific information to date.

Foundation for Dental MaterialsFor dental materials, the clinical research effort has been limited,representing only about 10% of all research for many years."' "Clinical trials require much more time and expense than labora-tory investigations of properties or clinical simulations. Only a fewlaboratory investigations have shown correlations with actualclinical results." This occurs for a variety of reasons. Individuallaboratory properties (such as ñexural strength) do not line up wellwith the performance data measured clinically for restoration

surfaces and margins. Simulations are attemptsto bridge the gap, but they are generally too lim-ited in design, not validated, use water to mim-ic saliva, and are not conducted long enough torepresent reasonable clinical lifetimes. As indi-cated in Table 2," a large range of laboratoryproperties could be tested. However, research-ers face significant challenges in detectingmeaningful correlations (C) between labora-tory tests and simulations (small circles in Fig-ure 4) and clinical results or combinations ofclinical data (small boxes in Figure 4). Relation-ships (R) may occur with laboratory or clinicalresults that do not produce correlations. Figure4 also shows types of factors that typically con-found data for the lab and clinic.

Table 2 provides examples of the wide range oflaboratory tests performed on dental materials

^ ^ ^ ^ ^ ^ ^ ^ for physical, chemical, mechanical, and biologicalproperties, as well as clinical manipulation andclinical performance properties. Typically, only

a couple are tested, and the results do not correlate with clinicalproperties. Table 2 summarizes the limited range of clinical catego-ries evaluated. The original categories were published by Cvar andRyge' while working for the United States Public Health System(USPHS). They are; color match, marginal discoloration, secondarycaries, anatomic form, marginal adaptation, and surface texture.The original list has been expanded to include more information,such as: proximal contact, functional occlusion, axial contour, pre-and postoperative sensitivity, restoration retention, and resistanceto fracture. Most of these categories concern clinical observationsof restoration margins or surfaces, and a rating system (A - Alia =clinically "ideal"; B - Bravo = clinically "acceptable"; C - Charlie =clinically "unacceptable") is used to determine clinical steps fromidea to failure.

Almost all dental materials trials are short-term (1 to 5 years)and involve low-risk participants. Generally, about 20% of thepopulation is considered at high risk for dental caries. Because of

Summary of Dental Materials Reports fromThree Major Evidence Libraries for DirectRestorative Riomaterials

Source

CochraneCollaborationLibrary

ADA EBD-ibrary

UTHSCSA CATS-ibrary

RestorativeBiomaterialsTopics

7

69

60

TotalReferences

152

2,300

186

%Bio-materials

4.6%

3.1%

32.3%

www.compendiumlive.com January 2014 COMPENDIUM 23

CONTINUING EDUCATION 1 i EBD AND DENTAL MATERIALS

pre-existing restorations, lost teeth, or existing dental caries, thathigh-risk group is primarily excluded from trials. As a result ofthese two practices combined, reports of dental restorative materi-als' clinical performance are generally very positive. Understandingpotential differences or problems, however, requires that failuresand their patterns be observed. These are missing from most dentalmaterials clinical trials.

Finally, the prevalence of clinical research reports from the differ-ent EBD library databases must be considered. As shown in Table 3,

which provides a summa-Related Con ten t:

Flowable Composite Resins:Do They Decrease Microleakageand Shrinkage Stress?

ry of dental materials re-ports for three major evi-dence libraries for directrestorative biomaterials,many of these reportsconclude that there waslittle or no sufficient or

^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ good evidence availableat the time of the report.

The number of reports involving dental materials that appeared inOctober 2013 in the Cochrane Collaboration, ADA EBD Library, andUTHSCSA CATS library were 12,89, and 69, respectively. For the firsttwo, fewer than 5% of the libraries discovered information. For thelast one, the inclusion of laboratory research in the process elevatesit to 32%. It is clear that very little information exists. Compilingthe evidence needed to answer 50% of the important questions willstill require 15 to 20 more years and much more concerted efforts.

SummaryEvidence for restorative dental materials performance is very lim-ited due to the scarcity of clinical trials. A much greater effort toconduct clinical research over the next 15 to 20 years is required tobuild the needed evidence base. Fast access to the available knowninformation is already possible.

ABOUT THE AUTHORS

Stephen C. Bay ne, MS, PhDProfessor and Chair, Cariology, Restorative Sciences, and Endodontics, School ofDentistry, University of Michigan, Ann Arbor, Michigan

Mark Fitzgerald, DDS, MSAssociate Professor and Vice Chair, Cariology, Restorative Sciences, and Endodontics,School of Dentistry, University of Michigan, Ann Arbor, Michigan

Queries to the author regarding this course may be submitted toauthorqueries@aegiscomm.com.

REFERENCES

1. Cochrane AL. Effectiveness and Efficiency. Random Reflections on HealthServices. London, England: The Nuffield Provincial Hospitals Trust; 1972.2. Ismail Ai. Bader JD. Evidence-based dentistry in clinical practice. JAm DentAssoc. 2004;135(l):78-83.3. Sackett DL, Richardson WS, Rosenberg W, Haynes RB. Evidence-based t^edicine: How to Practice and Teach EBM. New York, NY:Churchill Livingstone; 1997.4. Niederman R, Badovinac R. Tradition-based dental care andevidence-based dental care. J Dent Res. 1999;78(7):1288-1291.

5. Bayne SC, Marshall SJ. 20-year analysis of basic vs applied DMG-IADRresearch abstracts [abstract]. J Dent Res. 1999:78:130. Abstract 196.6. Duke ES. The Changing Practice of Restorative Dentistry. Indianapolis,IN: Indiana University School of Dentistry: 2000.7. Richardson yvs. Wilson MC, Nishikawa J, Hayward RS. The well-built clinical question: a key to evidence-based decisions. ACPJ Club.1995:123(3):A12-A13.8. Toh SL, Messer LB. Evidence-based assessment of tooth-colored resto-rations in proximal lesions of primary molars. Pediatr Dent. 2007:29(l):8-15.9. Sainani KL, Popat RA. Understanding study design. PM R. 2011:3(6):573-577.10. Spilker B. Guide to Clinical Trials. Philadelphia, PA: Lippincott Williams& Wilkins: 1991.11. Bayne SC. Dental restorations for oral rehabilitation - testing oflaboratory properties versus clinical performance for clinical decision-making. J Oral Rehabil. 2007:34(12):921-932.12. Cvar JF, Ryge G. Criteria for the Clinical Evaluation of DentalRestorative Materials. San Francisco, CA: US Department of Health.Education, and Welfare: 1971.13. Bayne SC, Schmalz G. Reprinting the classic article on USPHSevaluation methods for measuring the clinical research performance ofrestorative materials. Clin Oral Investig. 2005:9(4):209-214.14. Bayne SC. Correlation of clinical performance with 'in vitro tests'of restorative dental materials that use polymer-based matrices. DentMater. 2O12:28(l):52-71.15. Bayne SC, Heymann HO, Sturdevant JR, et al. Contributing co-variables in clinical trials. Am J Dent. 1991:4(5):247-250.16. Hickel R, Roulet JF, Bayne SC, et al. Recommendations for con-ducting controlled clinical studies of dental restorative materials. Part1: study design. IntDentJ. 2OO7:57(5):3OO-3O2.17. Hickel R, Roulet JF, Bayne SC, et al. Recommendations for conduct-ing controlled clinical studies of dental restorative materials. Part 2:criteria for evaluation. J Adh Dent. 2007:9 suppi 1:121-147.18. Brunson WD, Bayne SC, Shurdevant JR, et al. Three-year clinical evalua-tion of a self-cured posterior composite resin. Dent Mater. 1989:5(2):127-132.19. Wilder AD Jr, May KN Jr, Bayne SC, et al. Seventeen-year clinicalstudy of ultraviolet-cured posterior composite Class I and II restora-tions. J Esthet Dent. 1999:11(3):135-142.20. Swift EJ Jr, Perdigao J, Heymann HO, et al. Eighteen-month clinicalevaluation of a filled and unfilled dentin adhesive. J Dent. 2001:29(l):1-6.21. Swift EJ Jr, Perdigao J, Wilder AD Jr, et al. Clinical evaluation oftwo one-bottle dentin adhesives at three years. J Am Dent Assoc.2001:132(8):1117-1123.22. Crombie IK, Davies HT. What is meta-analysis? In: Evidence-basedMedicine? 2ná ed. London, England: Hayward Medical Communica-tions: 2009:1-8. http://www.medicine.ox.ac.uk/bandolier/painres/download/whatis/meta-an.pdf. Accessed November 20, 2013.23. Taylor DF, Bayne SC, Leinfelder KF, et al. Pooling of long term clini-cal wear data for posterior composites. Am J Dent. 1994:7(3):167-174.24. Hemingway P. Brereton N. What is a systematic review? In:Evidence-based Medicine? 2nd ed. London, England: Hayward MedicalCommunications: 2009:1-8. http://www.medicine.ox.ac.uk/bandolier/painres/download/whatis/syst-review.pdf. Accessed November 20, 2013.25. Cunha-Cruz J, Stout JR, Heaton LJ, et al. Dentin hypersensitivityand oxalates: a systematic review. J Dent Res. 2011:90(3):304-310.26. Rugh JD, Sever N, Glass BJ, Matteson SR. Transferring evidence-based information from dental school to practitioners: a pilot "academicdetailing" program involving dental students. J Dent Educ. 2011:75(10):1316-1322.

27. Sauvé S, Lee HN, Meade MO. et al. The critically appraised topic: apractical approach to learning critical appraisal. Ann R Colt PhysiciansSurg Can. 1995:28(7):396-398.28. Bayne SC, Grayden SK. DMG-IADR Abstract Research Patterns byType, Focus, and Funding [abstract]. J Dent Res. 2008:87(spec iss A).Abstract 1093.

24 COMPENDIUM January 2014 Volume 35, Number 1

Copyright of Compendium of Continuing Education in Dentistry (15488578) is the propertyof AEGIS Communications, LLC and its content may not be copied or emailed to multiplesites or posted to a listserv without the copyright holder's express written permission.However, users may print, download, or email articles for individual use.