Description of Treatment
It was discussed that tooth No. 7 would have to be extracted due to the advanced bone loss and active infection. A removable appliance was considered as an alternative. However, a resin-bonded pontic was preferred by the patient. The technique used to bond and repair porcelain intraorally would be the foundation for this segment of the rehabilitation.
In the initial appointment, restoration of the abfraction lesions of abutment teeth Nos. 9 and 11 and build-out of the pontic on No. 10 were completed. Two appointments to create a preparation and bond a porcelain pontic for No. 7 followed.
The exposed, discolored dentin surfaces were roughened with a coarse round carbide bur (801 018 [KOMET USA]) and the superficial staining removed. The adjacent porcelain surface was prepared with a very light bevel. The beveled porcelain was etched with hydrofluoric (HF) acid for 5 minutes and the dentin was conditioned with 37% phosphoric acid for 15 seconds. A silane porcelain primer (BIS-SILANE [BISCO]) was applied to the beveled porcelain surface. A light-cured bonding agent (ALL-BOND 3 [BISCO]) was applied to both porcelain and dentin. A composite resin opaquing agent was applied as a thin coat to the dark-colored dentin and exposed metal collar of the prosthesis (Figure 5). This material handles similar to a flowable resin. An opaque masking agent (CLEARFIL ST OPAQUER [Kuraray]) is necessary as restorative composite resin has some degree of translucency, allowing the dark discoloration to negatively affect the aesthetics of the restoration. After the opaquer was light-cured, the restoration was built to full contour, finished, and polished.
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| Figure 5. Flowable resin opaquer (Clearfil Majesty Esthetic [Kuraray]) applied to darkened root surfaces. |
The space between the pontic and edentulous ridge was then addressed. A variety of manufacturers have created porcelain repair systems such as CLEARFIL Porcelain Repair Kit (Kuraray), Porcelain Prep Kit (Pulpdent), and Porcelain Repair Kit (BISCO). These systems frequently demonstrate statistically similar shear bond strengths. Many of the specimens exhibit cohesive fracture in the porcelain. The undersurface of the pontic was roughened with a coarse diamond bur (849L [KOMET USA]). The porcelain surface to be built out was then etched with HF acid and silanated. HF acid and silanating agents are available in many porcelain repair kits or kits designed for bonding of all-ceramic restorations. It is important to follow the manufacturer’s recommendations and protect the gingival tissues from the caustic HF acid with a conventional rubber dam or a syringable dam material (OraSeal or OpalDam [Ultradent Products]).
Proper silanation may be the most important step in achieving a strong, reliable bond. Depending on the manufacturer’s recommendation, etching times will vary from 20 seconds to 10 minutes. The concentration of HF acid varies between 5% and 10%. Silane primers have a carbon chain that presents an SiO2 group in a functional end. The functional end bonds to the porcelain, allowing the free carbon chain to bond to the resin.