Rehabilitation of a Periodontally Compromised Case Using the Conical Crown System Part II

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Kassiani Stamouli, DDS, Dr med dent

Clinical Associate Professor

Department of Prosthodontics, School of Dentistry

University of Freiburg, Germany

Sjoerd Smeekens, DDS, Dr med dent

Clinical Associate Professor

Department of Prosthodontics, School of Dentistry

University of Freiburg, Germany

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THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY

VOLUME 4 • NUMBER 2 • SUMMER 2009

164

Rehabilitation of a Periodontally

Compromised Case Using

the Conical Crown System.

Part II.

Correspondence to: Dr Kassiani Stamouli

Sundgauallee 55, 79114 Freiburg, Germany

phone: +49 761 270 4838; e-mail: [email protected]

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STAMOULI/SMEEKENS

cations and limitations of both the fields of

fixed and removable prosthodontics. The

first part of this article deals with the vari-

ous prosthodontic treatment options, to-

gether with the advantages and disad-

vantages related to each one. This second

part of the article presents the final treat-

ment plan, the decision-making process,

and the sequence of the treatment steps.

(Eur J Esthet Dent 2009;4:164–176.)

Abstract

The aim of this two-part treatment series

is on the one hand to emphasize the dif-

ficulties a clinician is confronted with

when planning complex cases, and on

the other hand to reveal the rationale sup-

porting the final treatment plan selection.

Among the challenging cases to be con-

sidered are periodontal compromised

rest dentitions requiring prosthodontic re-

habilitation. For these patients the deci-

sion-making process deals with the indi-

165THE EUROPEAN JOURNAL OF ESTHETIC DENTISTRY


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166

conium dioxide (ZrO2) copings are not nu-

merous, their findings are lacking in evi-

dence, and only case reports on primary

crowns made from ZrO2 with the applica-

tion of the CAD/CAM technology exist.1In

the mandible, due to the reduced esthetic

demands, traditional gold primary crowns

were planned.

Treatment steps

Preliminary treatment

The hopeless teeth 16, 14, 12, 21, 22, 26,

33, and 46 were extracted, followed by the

immediate placement of the provisional

prostheses. In collaboration with the den-

tal hygienist, periodontal therapy was per-

formed and re-evaluated after 4 to 6

weeks. The major reduction of probing

Final decision

The final decision was taken after consider-

ing both the patient’s priorities and scientif-

ic objectives. While taking into consideration

the wishes of the patient, as well as the ben-

efits and limitations of the various treatment

modalities presented, the following decisive

parameters were evaluated (Table 1).

In the present case, the advantages of a

conical crown prosthesis were comparable

to the other treatment options. However,

the compensation of ridge defects and the

extensibility/repairability made it the most

favorable type of prosthesis. To overcome

the disadvantages (i.e. avoid the sub-

gingival abutment preparation and the vi-

sibility of gold margins), it was decided to

fabricate full ceramic primary crowns.

However, controlled clinical trials and long-

term data on the clinical behaviour of zir-

Table 1 Advantages and limitations of fixed and removable dental prostheses

Clasp- Attachment- Conical Fixed

Partial Denture retained retained crown-retained

Patient comfort - + + +

Esthetics - + +/- +/-

Compensation of ridge defects + + + -

Phonetics - + + +/-

Invasiveness - +/- + +

Fabrication complexity - + +/- +/-

Extensibility/repairability - - + -

Palatal coverage required - - +/- +

Oral hygiene performance + + + -

Economics + - +/- -

Long-term clinical performance - +/- +/- +

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167

tance (phonetic tests used m-sound

pronunciation [2–3 mm interarch space]

and s-sound pronunciation [no teeth

contact]), existing freeway space of

2 mm.

- the midline.

� Tooth 11 served as the reference point

indicating the length of the incisal edge.

� The smile line and occlusal plane.

After initial tooth preparation, provisional-

ization, and bite registration the technician

fabricated the diagnostic try-in setup (Figs

1 to 4). This setup offered the opportunity

to evaluate and visualize the treatment goal

depths allowed the initial prosthodontic

treatment plan to be carried out.

Diagnostic phase

Prior to tooth preparation, impressions

were taken from both the maxilla and the

mandible. On the casts obtained, the tech-

nician fabricated wax register plates, which

were used for bite registration. During the

next patient visit the following aspects were

controlled.

� The vertical dimension was maintained:

- facial/lip support, maxillomandibular dis-

Fig 1 Diagnostic setup on the mounted casts. Fig 2 Try-in of the diagnostic setup.

Figs 3 and 4 Basal views of the diagnostic setups.

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Fig 5 Control with silicon key (made from the setup)

of the initial tooth preparation.

Fig 6 Definitive space control before taking impres-

sion.

Figs 9 and 10 Try-in of the maxillary and mandibular primary copings.

Figs 7 and 8 Occlusal view of all teeth before taking impression.

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169

and the prospective tooth form and out-

come of the removable dental prosthesis.

It served also as an effective communica-

tion tool among the patient, clinician, and

the dental technician.

Prosthodontic phase

After correcting the try-in setup, silicon keys

were made to serve as a guide for the de-

finitive abutment preparation (Figs 5 and

6). This process assured that an optimal

amount of tooth substance was removed.

This step is of great importance, since the

conical crown system requires a substan-

tial amount of tooth substance to be re-

moved. The location of the margins were

kept epigingivally. With respect to long-

term maintenance of periodontal health,

studies have shown that a supragingival lo-

cation of the crown margin is more favor-

able compared with a subgingival loca-

tion.2,3

From an esthetic point of view, this

approach did not have any disadvantages,

because the primary copings were fabri-

cated out of ZrO2 in the maxilla. After the

teeth had been definitively prepared (Figs

7 and 8), impressions were taken with cus-

tomised trays and PermadyneTM

GarantTM

(3MTM

ESPETM

, Seefeld, Germany).

The fabrication of the stone dies fol-

lowed at the dental laboratory. For the max-

illa, the ZrO2 primary copings were fabri-

cated with the Zeno®

Tec (Wieland Dental,

Germany) CAD/CAM system. First, the

stone dies were scanned in the 3D shape

200 Scanner. The copings (Fig 9) were

then milled out of Zeno®

Zr Discs (partially

sintered yttria tetragonal zirconia polycrys-

tal [Y-TZP]) in the Zeno®

4030 M1 CAM unit

(Wieland Dental). For the mandible, con-

ventional gold (BioMaingold SG, Heraeus

Figs 11 to 13 Occlusal and facial view of the sec-

ondary frameworks.

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Figs 14 and 15 Gingival and facial view of the fabricated maxillary conical crown denture.

Fig 16 Facial view of both conical crown dentures. Fig 17 Occlusal view of the maxillary conical crown

denture.

Fig 18 Focused facial view of the maxillary anterior

part of the reconstruction.

Fig 19 Occlusal view of the mandibular conical

crown denture.

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Kulzer, Hanau, Germany) primary cop-

ings were fabricated (Fig 10). The try-in

process of all primary copings revealed a

good marginal fit. Impressions of the max-

illa and mandible with customized trays

and ImpregumTM

PentaTM

(3M ESPE) were

taken over the primary copings, for the

fabrication of the master models. With a

face bow transfer and a bite registration

with wax plates, the master models were

mounted in the articulator. The desired

vertical dimension was transferred exact-

ly by using the provisional restorations.

The technician fabricated the secondary

frameworks (Figs 11 to 13) for the tele-

scope dentures on the mounted master

models. At the maxilla, owing to the favor-

able abutment distribution, a palatal-con-

nector-free framework was achieved (Figs

14 and 15). After trying in the frameworks of

both arches, the primary setup and the cor-

responding provisional restorations were

used as a reference for the final removable

dental prostheses.

The clinical re-evaluation before ce-

mentation revealed that the patient was

satisfied with both the function and the es-

thetics of the restorations (Figs 16 to 21).

All remaining teeth showed a probing

depth of less than 4 mm, negative bleed-

ing on probing, and a positive reaction to

the vitality test. The periodontal status be-

fore cementation is presented in Figure

22. The radiographic evaluation before

cementation also revealed healthy dental

and periodontal relations (Fig 23). Finally,

all primary copings were cemented with

KetacCem (3M ESPE). After removing the

cement rests, the removable dental pros-

theses were inserted. The patient received

instructions for meticulous home care and

was integrated into a 4-month recall pro-

gram.

Fig 20 Patient smiling after the insertion of the coni-

cal crown dentures.

Fig 21 Smile of the patient after rehabilitation

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Fig 23 Radiographic evaluation before cementation.

Fig 22 Periodontal status before cementation (Furc: furcation involvement, PD: probing depth, AL: attachment

loss).

PD

AL

mm

mm

AL

PD

Furc

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In cases of favorable number, distribution,

and condition of the abutment teeth (as in

the present case) the secondary denture-

framework can be fabricated without sup-

porting big connectors (palatal, lingual

bar).6,7

Moreover, a cementation of the re-

construction with a temporary cement is

also possible. This modification allows the

restoration to be retrieved if needed. In

case of de-cementation, there is no risk of

secondary caries, as the failure zone is

between the primary and the secondary

crown. The primary crown, which was ce-

mented on the tooth, remained intact

showing a good marginal fit. Another as-

pect that should not be underestimated is

the feeling of having fixed restorations in

a patient’s mouth. For many patients, this

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173

Discussion

This article describes the application of the

conical crown system for the oral rehabili-

tation of a patient with advanced periodon-

tal disease. In such a case, rehabilitation

with a fixed prosthesis would increase the

risk of failure, whereas a removable dental

prosthesis can be retrieved and repaired,

and is therefore flexible.4,5

However, the lack

of stability, the limited esthetics and the low

patient comfort make removable prosthe-

ses unattractive for patients as well for the

clinicians.

Therefore, the conical crown system and

its variable modifications are considered to

be a suitable prosthesis to cover the gap

between fixed and removable prostheses.

Fig 24 Orthopantogram after 18 months of function.

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Fig 25 Fig 26 Fig 27

Fig 28 Fig 29

Fig 30

Figs 25 to 31 Intraoral views of the patient after 18 months of function.

Fig 31

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is of high priority, offering an improved

quality of life and increased self-esteem

and confidence.

On the other hand, the gold margins, the

view of metal in the oral cavity, and the

overcontour are major disadvantages. The

increasing demand for more esthetic and

natural-looking restorations has led to an

advanced development of ceramic mate-

rials.8-10

The low fracture strength of the tra-

ditional ceramics limits their wide applica-

tion.8The improved mechanical properties

of the new high-strength ceramics, espe-

cially the ZrO2 ceramics, have expanded

their application for reconstructions under

increased loading1. This allows the appli-

cation of ZrO2 for the fabrication of primary

copings for the conical crown system,

avoiding the unattractive gold margins and

achieving an esthetically and functionally

pleasing restoration. However, to avoid the

visibility of the anterior maxillary secondary

crowns, the core margins were cut back

buccally up to 2 mm (vertically) and shoul-

der composite was applied according to

the facial porcelain margin principle of

Shillingburg.11-13

From both the esthetic and functional

point of view the end result was satisfying.

At the 3-, 6-, 12-, and 18-month recall inter-

vals the periodontal re-evaluation revealed

healthy hard- and soft-tissue relations. An

orthopantogram (Fig 24) after 18 months

of function revealed healthy dental and pe-

riodontal relations. Figures 25 to 31 show

intraoral views of the patient after 18

months. The patient reported an enhance-

ment in quality of life (Fig 32).

Generally, it is well established that self-

performed plaque control, combined with

regular attendance of maintenance care

following active periodontal treatment, rep-

resents an effective means of controlling

gingivitis and periodontitis and limiting

tooth mortality over a 30-year period.14

Acknowledgements

The authors would like to thank the dental laboratory

Woerner Zahntechnik, Freiburg, Germany for the tech-

nical part of the case.

Fig 32 Patient reported of an enhancement in qual-

ity of life.

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10. Sadan A, Blatz MB, Lang B.

Clinical considerations for

densely sintered alumina and

zirconia restorations: Part 2. Int

J Periodontics Restorative Dent

2005;4:343–349.

11. Shillingburg HT Jr, Hobo S,

Fisher DW. Preparation design

and margin distortion in porce-

lain-fused-to-metal restora-

tions. J Prosthet Dent

1973;3:276–284.

12. Goodacre CJ, Van Roekel NB,

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A, Genini P. Improved esthetics

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5. Wenz HJ, Hertrampf K,

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struktion. Eine Langzeitstudie.

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Documents

Rehabilitation of a Periodontally Compromised Case Using the Conical Crown System Part II