Vasconcellos et al

Impression technique for ovate pontics

Diego Klee de Vasconcellos, DDS, MSc, PhD,a Cláudia Ângela Maziero Volpato, DDS, MSc, PhD,b Izo Milton Zani, DDS, MSc, PhD,c and Marco Antonio Bottino, DDS, PhDd

Federal University of Santa Catarina, Florianópolis, Santa Catarina, Brazil; São José dos Campos School of Dentistry, São Paulo State University (UNESP), São José dos Campos, São Paulo, Brazil

aAdjunct Professor, Department of Dentistry, Federal University of Santa Catarina.bAdjunct Professor, Department of Dentistry, Federal University of Santa Catarina.cAssociate Professor, Department of Dentistry, Federal University of Santa Catarina.dFull Professor, Department of Dental Materials and Prosthodontics, São José dos Campos School of Dentistry, São Paulo State University (UNESP).(J Prosthet Dent 2010;105: 59-61)

A convex surface has been ad-vocated for the pontics of posterior and anterior fixed partial dentures (FPDs).1 A modified ridge lap pontic establishes gentle contact on the la-bial surface of the alveolar mucosa, with no contact on the palatal sur-face.2,3 This design facilitates good oral hygiene and cleaning of the pon-tic. However, esthetics are compro-mised, since a complete emergence profile cannot be obtained because of the convex shape of the alveolar ridge. In addition, this design commonly creates palatal food traps and causes phonetic difficulties, as air and saliva are pushed through from the lingual surface.4

The ovate pontic design, as de-scribed in the literature,1,4,5 allows-for an excellent esthetic outcome. To sculpt the tissue beneath the pontics, provisional restorations with ovate pontic designs should be provided for tissue guidance and stabilization.1 The controlled pressure applied to the soft tissues of the residual ridge by the smooth convex pontic, along with good plaque control, results in a thin-ning of the epithelium and shortening of rete pegs, without causing tissue

inflammation.6 The sculpted tissue beneath the pontics must be accu-rately transferred to a cast to provide the dental laboratory technician with the necessary information to fabri-cate a definitive restoration with an appropriate emergence profile.4,5,6

Use of elastomeric materials to make the impression of the alveo-lar mucosa, regardless of the tech-nique used, may alter the shape of the sculpted tissue due to the den-sity of the impression material. This may provide inaccurate information to the dental laboratory technician with respect to the tissue contours. Additionally, the shape of the alveo-lar mucosa may be distorted during the impression making due to tissue collapse caused by the removal of the provisional FPD.

This article describes a safe and effective impression technique for use when fabricating ovate pontics. In this method, the provisional resto-ration is used for easy and accurate transfer of the tissue features to the cast, avoiding tissue collapse caused by the removal of the provisional FPD and tissue compression produced by the impression material. This tech-

nique allows the fabrication of a reli-able cast so that the dental laboratory technician can appropriately develop the definitive FPD. Mucosa will remain healthy irrespective of the definitive pontic material used (metal or por-celain), if the patient maintains good oral hygiene and removes plaque ef-ficiently from the smooth convex pon-tic area.7 However, the technique has limitations. The framework is fabri-cated without information regarding the definitive gingival contours and, therefore, may not provide adequate support for the porcelain in particular areas.

PROCEDURE

1. Create a provisional restoration that simulates the design of the de-finitive restoration.

2. Use the provisional restora-tion to sculpt the soft tissue, as rec-ommended by Jacques et al1 (Fig. 1, A). After tissue sculpting, make a complete arch impression by using a custom tray fabricated with light-po-lymerizing material (Triad; Dentsply Intl, York, Pa) and polyether impres-sion material (Impregum F; 3M ESPE,

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St. Paul, Minn). Use nonimpregnated retraction cord for gingival retraction (Ultrapack Cord no. 00; Ultradent Products, Inc, South Jordan, Utah). Cast the impression with type IV den-tal stone (Durone; Dentsply Intl, York, Pa) to produce a definitive cast that will allow the dental laboratory tech-nician to fabricate the FPD framework (InCeram Alumina; VITA Zahnfabrik,

Bad Säckingen, Germany). 3. Evaluate the framework intra-

orally. Use the customized transfer impression technique as described in the following steps.

4. With the provisional FPD in po-sition (without provisional cement), make a transfer impression of the FPD, using a heavy-body vinyl poly-siloxane material (Zetaplus System;

Zhermack SpA, Rovigo, Italy). Remove the impression from the mouth, ensur-ing that the provisional restoration re-mains in the impression (Fig. 1, B).

5. Isolate the impression and the provisional restoration with petro-leum jelly. Inject a medium-body vi-nyl polysiloxane impression material (Aquasil; Dentsply Intl, York, Pa) into the impression to obtain a silicone

1 A, Occlusal view of sculpted alveolar mucosa. B, Provisional FPD inside impres-sion. C, Framework on silicone cast. Pontic site reproduced with acrylic resin.

2 A, Frontal view of cast with removable silicone artificial gingiva. B, Definitive restoration placed intraorally.

A B

C

BA

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Vasconcellos et al

cast (silicone allows the cast to be made as quickly as possible, while the patient is waiting). After the impres-sion material polymerizes, remove the silicone cast from the impression. If necessary, trim the silicone cast with a surgical scalpel (No. 11; Hu-Friedy Co, Inc, Chicago, Ill).

6. Adapt the FPD framework on the silicone cast. With the bead-brush technique, place acrylic resin (GC Pattern Resin; GC America, Inc, Alsip, Ill) beneath the pontic, until contact with the pontic site of the silicone cast is obtained. Note that the gingi-val surface of the provisional pontic is reproduced by the acrylic resin and will remain joined to the framework pontic (Fig. 1, C).

7. Place the customized FPD framework intraorally over the abut-ment teeth and make a definitive transfer impression using heavy- and light-body vinyl polysiloxane (Aquasil; Dentsply Intl) simultaneously.

8. Pour the impression with soft

tissue cast material (Coltex Extrafine; Coltene Whaledent, Inc, Cuyahoga Falls, Ohio) and type IV dental stone (Durone; Dentsply Intl) to create a cast with artificial gingiva represented in silicone (Fig. 2, A). Note that the soft tissue cast material used in the pontic site to avoid fracture of thin plaster margins in this area allows the dental technician to fabricate a pon-tic with contours identical to those of the provisional pontic (Fig. 2, B).

REFERENCES

1. Jacques LB, Coelho AB, Hollweg H, Conti PC. Tissue sculpturing: an alternative method for improving esthetics of anterior fixed prosthodontics. J Prosthet Dent 1999;81:630-3.

2. Becker CM, Kaldahl WB. Current theo-ries of crown contour, margin place-ment and pontic design. J Prosthet Dent 1981;45:268-77.

3. Howard WW, Ueno H, Pruitt CO. Stan-dards of pontic design. J Prosthet Dent 1982;47:493-5.

4. Dylina TJ. Contour determination for ovate pontics. J Prosthet Dent 1999;82:136-42.

5. Edelhoff D, Spiekermann H, Yildirim M. A review of esthetic pontic design options. Quintessence Int 2002;33:736-46.

6. Tripodakis A, Constantinides A. Tis-sue response under from convex pon-tics. Int J Periodontics Restorative Dent 1990;10:408-14.

7. Zitzmann NU, Marinello CP, Berglundh T. The ovate pontic design: a histologic observation in humans. J Prosthet Dent 2002;88:375-80.

Corresponding author:Dr Diego Klee de VasconcellosDepartment of DentistryFederal University of Santa CatarinaRua: Dom Joaquim, 866, ap 801Florianópolis, SCCEP: 88015-310BRAZILFax: +55 48 3721 9520E-mail: diegokv@terra.com.br

AcknowledgmentsThe authors thank dental technician Márcio Breda, and Wilcos (Petrópolis, Brazil) and Conexão Sistemas de Prótese (São Paulo, Brazil) for their support of this study. The ce-ramic used in this study was provided by VITA Zahnfabrik (Bad Säckingen, Germany).

Copyright © 2010 by the Editorial Council for The Journal of Prosthetic Dentistry.

Noteworthy Abstracts of the Current Literature

Survival rates of porcelain molar crowns—an update

Kassem AS, Atta O, El-Mowafy O.Int J Prosthodont 2010;23:60-2.

The aim of this study was to identify recent studies that dealt with the clinical performance of porcelain molar crowns and to explore the possibility of grouping the findings from similar studies together to draw overall conclusions. A MEDLINE literature search was conducted in early 2009 covering the preceding 12 years. Seventeen studies were iden-tified. However, only seven met the specific inclusion criteria and were analyzed. Among seven studies, five European countries were covered. Five studies reported on Procera AllCeram molar crowns while one reported on In-Ceram Alumina and Spinell crowns and another on CEREC crowns. For comparison, one additional study that reported on premolar crowns was included. In the five Procera AllCeram studies, 235 molar crowns were evaluated for 5 or more years, of which 24 failed. When the results of the five studies on the performance of Procera AllCeram molar crowns were considered collectively, an overall failure rate of 10.2% was found at 5 or more years.

Reprinted with permission of Quintessence Publishing.