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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
A convex surface has been advocated for the pontics of posterior
and anterior fixed partial dentures
(FPDs).1 A modified ridge lap pontic
establishes gentle contact on the labial surface of the alveolar mucosa,
with no contact on the palatal surface.2,3 This design facilitates good
oral hygiene and cleaning of the pontic. However, esthetics are compromised, 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 described in the literature,1,4,5 allowsfor 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 thinning of the epithelium and shortening
of rete pegs, without causing tissue
inflammation.6 The sculpted tissue
beneath the pontics must be accurately transferred to a cast to provide
the dental laboratory technician with
the necessary information to fabricate a definitive restoration with an
appropriate emergence profile.4,5,6
Use of elastomeric materials to
make the impression of the alveolar mucosa, regardless of the technique used, may alter the shape of
the sculpted tissue due to the density 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 alveolar 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 restoration 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 reliable 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 porcelain), if the patient maintains good
oral hygiene and removes plaque efficiently from the smooth convex pontic area.7 However, the technique has
limitations. The framework is fabricated 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 definitive restoration.
2. Use the provisional restoration to sculpt the soft tissue, as recommended by Jacques et al1 (Fig.
1, A). After tissue sculpting, make a
complete arch impression by using a
custom tray fabricated with light-polymerizing material (Triad; Dentsply
Intl, York, Pa) and polyether impression material (Impregum F; 3M ESPE,
Adjunct Professor, Department of Dentistry, Federal University of Santa Catarina.
Adjunct Professor, Department of Dentistry, Federal University of Santa Catarina.
c
Associate Professor, Department of Dentistry, Federal University of Santa Catarina.
d
Full Professor, Department of Dental Materials and Prosthodontics, São José dos Campos School of Dentistry, São Paulo State
University (UNESP).
a
b
(J Prosthet Dent 2010;105: 59-61)
Vasconcellos et al
60
7PMVNF*TTVF
A
B
C
1 A, Occlusal view of sculpted alveolar mucosa. B, Provisional FPD inside impression. C, Framework on silicone cast. Pontic site reproduced with acrylic resin.
A
B
2 A, Frontal view of cast with removable silicone artificial gingiva. B, Definitive restoration placed intraorally.
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 dental stone (Durone; Dentsply Intl, York,
Pa) to produce a definitive cast that
will allow the dental laboratory technician to fabricate the FPD framework
(InCeram Alumina; VITA Zahnfabrik,
Bad Säckingen, Germany).
3. Evaluate the framework intraorally. Use the customized transfer
impression technique as described in
the following steps.
4. With the provisional FPD in position (without provisional cement),
make a transfer impression of the
FPD, using a heavy-body vinyl polysiloxane material (Zetaplus System;
The Journal of Prosthetic Dentistry
Zhermack SpA, Rovigo, Italy). Remove
the impression from the mouth, ensuring that the provisional restoration remains in the impression (Fig. 1, B).
5. Isolate the impression and the
provisional restoration with petroleum jelly. Inject a medium-body vinyl polysiloxane impression material
(Aquasil; Dentsply Intl, York, Pa) into
the impression to obtain a silicone
Vasconcellos et al
61
January 2011
cast (silicone allows the cast to be
made as quickly as possible, while the
patient is waiting). After the impression 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 gingival 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 abutment 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 pontic 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 theories of crown contour, margin placement and pontic design. J Prosthet Dent
1981;45:268-77.
3. Howard WW, Ueno H, Pruitt CO. Standards 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. Tissue response under from convex pontics. 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 Vasconcellos
Department of Dentistry
Federal University of Santa Catarina
Rua: Dom Joaquim, 866, ap 801
Florianópolis, SC
CEP: 88015-310
BRAZIL
Fax: +55 48 3721 9520
E-mail: [email protected]
Acknowledgments
The 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 ceramic 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 identified. 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.
Vasconcellos et al