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Int Chin J Dent 2005; 5: 65-70.

A direct composite fixed partial denture fabricated using a wax
mock-up technique: A clinical report
Toru Nikaido, DDS, PhD,a Masaomi Ikeda, BSc, RDT,a Richard M. Foxton, BDS, PhD,band Junji Tagami, DDS, PhDa,ca

Cariology and Operative Dentistry, Department of Restorative Sciences, Graduate School, Tokyob
Medical and Dental University, Tokyo, Japan, Division of Conservative Dentistry, Guy’s, King’s and St.
cThomas’ Dental Institute, Kings College of London, London, UK, and Member of the Center ofExcellence Program for Frontier Research on Molecular Destruction and Reconstruction of Tooth andBone, Tokyo Medical and Dental University, Tokyo, Japan
An 80-year-old woman was provided with a direct composite fixed-partial denture to replace a missing maxillary
first premolar using a wax mock-up technique. A wax mock-up was made in the laboratory and then a silicone
impression was taken of the basal aspect of the pontic to make silicone matrix. The surface of the adjacentmaxillary canine was not prepared and the bonding surface was expanded to any undercut areas and thedisto-labial/disto-buccal corners, while the adjacent maxillary second premolar had a MOD cavity as a retainer,
because of the removal of the secondary caries associated with a failed metal inlay. A composite fixed partial
denture was then directly fabricated at the chairside using the silicone matrix to shape the base of the pontic.
This is fairly minimally invasive prosthodontic treatment option for constructing a transitional fixed partialdenture. (Int Chin J Dent 2005; 5: 65-70.)
Key Words: adhesion, direct composite, fixed partial denture, pontic.

IntroductionThe development of good adhesive materials has enabled a minimally invasive approach to caries treatment to
be undertaken using a direct resin composite.1,2 This has also lead to the development of resin-bonded fixed
partial dentures (RBFPD) with metal frameworks as an alternative to full-preparation FPDs.3,4 Recently, resin
pre-impregnated fiber-reinforced composites (FRCs) have been developed, which offer high fracture strengthand tooth-colored metal-free frameworks.5,6 Fiber-reinforced composite FPDs can be fabricated either directly atchairside7-9 or indirectly in the laboratory.6,9 Adding fibers creates a layer, which could act as an impediment tocrack formation and debonding.10 However, in some pre-impregnated FRC materials, air bubbles trapped
between the fibers in the matrix may weaken the matrix and localize stresses that could lead to crack formation,
contributing to failures within the FRC matrix.10
It is generally thought that fiber-reinforced fixed partial dentures are not always necessary when replacing
only one missing tooth, if good adhesive materials and proper procedures are adhered to.11 The direct composite
fixed partial denture without fiber reinforcement is an option for fabricating three-unit FPDs. Previously,composite denture teeth have been used as pontics in RBFPDs.12 However, it is difficult to form the basal shapeof a pontic intraorally. The following case report describes how a direct composite fixed partial denture can bemade using a wax mock-up technique with minimal intervention.

Clinical Report
An 80-year-old patient attended the Operative Dentistry Clinic of the Dental Hospital of Tokyo Medical andDental University requesting treatment for a missing maxillary right first premolar. The adjacent canine was65

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Int Chin J Dent 2005; 5: 65-70.

intact and the second premolar had a gold MOD inlay with secondary caries (Fig. 1).

12Fig. 1. A missing maxillary right first premolar. The adjacent canine was intact and the second
premolar had a gold inlay with secondary caries.
Fig. 2. A wax mock-up of the missing first premolar was fabricated onto the working cast.

34Fig. 3. A wide contact area between the pontic and abutment teeth was provided to ensure maximum
surface area for bonding. A 0.5-mm space was provided between the base of the pontic andthe alveolar ridge.
Fig. 4. An impression of the basal surface of the pontic and the surrounding area was taken using aheavy body type silicone rubber impression material. Following this, the occlusal half wasremoved with a razor blade.
An irreversible hydrocolloid impression (Aroma Fine DFIII, GC, Tokyo, Japan) was taken to make a working
cast (New Fuji Rock, GC). A wax mock-up of the missing first premolar was fabricated (Parafin Wax, GC) (Fig.
2).
After forming the pontic, both the mesial and distal proximal surfaces of the wax pattern were heated to fix thepontic between the canine and the premolar. A 0.5-mm space was provided between the base of the pontic andthe alveolar ridge. A wide contact area between the pontic and abutment teeth was provided to ensure maximum
surface area for bonding (Fig. 3).
Following this, an impression of the basal surface of the pontic and the surrounding area was taken using aheavy body type silicone rubber impression material (Exafine Putty Type, GC). When the silicone had set, theocclusal half was removed with a razor blade (Fig. 4).
At the second visit, the gold inlay was removed with a tungsten carbide bur (#1931, GC) in an air-turbine
handpiece with water spray. After the cement remnants were ultrasonically removed, the caries-infected dentin
was carefully removed with a steel round bur (ISO#010, GC) in a low-speed micromotor handpiece leaving thecaries-affected dentin and intact dentin. Following this, the teeth were isolated with a rubber dam for thesubsequent bonding procedures (Fig. 5).

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56Fig. 5. After removal of the caries infected dentin, the teeth were isolated with a rubber dam for thesubsequent bonding procedures.
Fig. 6. The distal aspect of the second premolar was restored using a direct resin composite.

78Fig. 7. After applying the bonding system and a flowable resin composite, the silicone matrix was thenseated on the alveolar ridge between the abutment teeth.
Fig. 8. Composite placement began at the base of the pontic. A resin composite was incrementally
built-up and light-cured to connect the abutment teeth.
A steel sectional matrix (KerrHawe, Bioggio, Switzerland) was inserted in the interproximal space andwedged. A two-step self-etching adhesive (Clearfil SE Bond, Kuraray Medical, Tokyo, Japan) was applied to
the whole cavity according to the manufacturer’s instructions, and then a flowable composite was applied to thecured adhesive and light-cured for 30 s using a halogen light curing unit (New Light VL-II, GC). Following this,the distal aspect of the second premolar was restored using a direct resin composite, Estelite Σ (TokuyamaDental, Tsukuba, Japan) (Fig. 6).
The distal surface of the canine was prepared for bonding by grinding the enamel surface with a plastic strip(#1000, Inoue Attachment, Tokyo, Japan). Phosphoric acid (37%, K-etchant, Kuraray Medical) was thenapplied to the enamel surface for 30 s, rinsed and dried. Following this, SE Primer in Clearfil SE Bond wasapplied to the surface for 5 s and gently air-blown. SE Bond in Clearfil SE Bond was applied to the caninesurface and light-cured for 10 s. In addition, a flowable resin composite, Unifil Flow (GC), was applied to theadhesive surface and light-cured for 30 s. The sectional matrix at the distal site of the premolar was removed
and the silicone matrix was seated on the alveolar ridge between the abutment teeth (Fig. 7).
Composite placement began at the base of the pontic. A resin composite was incrementally built-up andlight-cured for 30 s at each step to connect the abutment teeth (Fig. 8).
After the build-up procedure, the silicone matrix was removed and the composite was light-cured from theocclusal, buccal and lingual sides for 30 s each. After checking for and removing any premature occulsal

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contacts, the restoration was finished and polished (Fig. 9).
The patient was recalled one week later to check for any problems at the pontic and interproximal areas. At
this point, there were no clinical symptoms such as occlusal problems or postoperative sensitivity.

Fig. 9.
Post-operative view of the direct composite
fixed partial denture fabricated using a wax
mock-up technique.

Discussion
Self-etching adhesive systems use weak acidic monomers to condition both the enamel/dentin substrates.13,14
Self-etching adhesive systems are effective in bonding resin composite to dentin.15 However, the application ofself-etching systems on enamel has been a controversial issue. It was reported that the adhesion of self-etchingadhesives to ground enamel was inferior when compared with systems utilizing phosphoric acid as a separate
conditioner.16,17 On the other hand, other studies have shown that self-etching systems might be a satisfactory
alternative to phosphoric acid conditioning of ground enamel.18,19 The acidity of the etchant may not have arelationship with bond strength to enamel.19 In this report, 37% phosphoric acid was applied to the canineenamel, which was un-ground enamel, while only a self-etching primer was applied to the enamel of the second
premolar, which was ground enamel.
Flowable composites have lower elastic moduli, lower filler contents and in general, inferior mechanicalproperties than traditional hybrid composites.20 However, the additional application of a flowable composite on
the cured adhesive significantly improves the sealing of the dentinal margins.21 Theoretically, a gradual change
in material properties at the interface could reduce stresses during loading of the restoration.22,23 At the hybrid
resin composite/tooth interface, application of a flowable composite between the hybrid composite and adhesive
resin is expected to result in a gradual change of properties from the outermost surface toward the tooth.24,25 It
has therefore been recommended to include a flowable composite in the chairside fabrication protocol ofRBFPDs.8
The pontic must meet certain structural requirements to ensure the mechanical stability of the restoration.26 Inaddition, the pontic must fulfill the complex roles of replacing the function of the lost tooth, achieving anesthetic appearance, enabling adequate oral hygiene, and preventing tissue irritation.27 At the chair-side, it isdifficult to fabricate a pontic with a correct relationship to the alveolar ridge and/or to the abutment teeth.
Therefore, before beginning treatment in the mouth, a working cast was fabricated onto which a pontic waswaxed. In order to maintain healthy soft tissues, a pontic with a smooth and convex shape was fabricated, 0.5
mm from the alveolar ridge. The bonding surfaces of the mesial/distal abutment teeth were extended as much as
possible to obtain a large adhesive interface. An impression of the basal surface was taken using a silicone putty
impression material.
A hybrid composite was used to build the pontic up incrementally. Composite placement began at the base of68

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the pontic. During polymerization, shrinkage stresses compete with the adhesive-tooth bond, potentially causing
failure of the bond and eventually, the restoration itself.28 To reduce curing stresses, an incremental technique
has been advocated when placing composite resin.29,30
Wear resistance is one of the most important factors affecting the longevity of direct composite FPDs. Recent
composite materials seem to have attained a balance of good wear resistance and low abrasiveness towards
antagonistic enamel.31 However, attritional wear may be a problem when composites are placed in heavy
contact.32 Occlusion has an important effect on the wear process. The distribution of forces can be alteredthrough selective occlusal adjustment. Multiple contact areas maintain occlusal stability by lowering stressconcentrations.33
Teeth have some degree of mobility under function, which causes repeated tensile and compressive stresses at
the adhesive joint, which would cause fatigue failures. The survival rate of resin-bonded FPDs is dependent
upon location, type and length of the FPD.3,4 The debonding rate of resin-bonded FPDs with a span greater than
one pontic is higher as a result of increased tensile stresses at the bonded interface from occlusal loads.34 In thecase of three-unit FPDs, a direct composite FPD without fiber reinforcement requires less invasive treatment
than conventional FPDs, which may be a new treatment option. Long-term clinical evaluation of this newtechnique will be carried out in the near future.
Acknowledgment
This study was supported by the grant for the Center of Excellence Program for Frontier Research on MolecularDestruction and Reconstruction of Tooth and Bone at Tokyo Medical and Dental University.

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Reprint request to:
Dr. Toru Nikaido
Cariology and Operative Dentistry, Department of Restorative Sciences
Graduate School, Tokyo Medical and Dental University
1-5-45, Yushima, Bunkyo-ku, Tokyo 113-8549, Japan
Fax: +81-3-5803-0195 E-mail: nikaido.ope@tmd.ac.jp
Received July 7, 2005. Revised August 5, 2005. Accepted August 10, 2005.
Copyright ©2005 by the Editorial Council of the International Chinese Journal of Dentistry.

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