Porcelain veneers: Dentin bonding optimization and biomimetic recovery of the crown

Purpose: The purpose of this study was to investigate the biomimetic princi ple in porcelain veneer reconstruction, or in other words, to assess the ex tent to which the restoration can mimic the biomechanics and structural int egrity of the original tooth. Using an optimized luting procedure, porcelai n veneers are expected to present such features even when bonded to an exte nsive dentin surface. Methods and Materials: Dentin-bonded porcelain veneer s were assessed using functional and cyclic thermal loads with respect to t wo parameters: coronal stiffness (investigated using experimental strain ga uges and finite element analysis) and morphology of the tooth-restoration i nterface (scanning electron microscope evaluation). Two different applicati on modes of the same dentin-bonding agent, Optibond FL, were evaluated: a t raditional method (dentin adhesive applied when proceeding to luting the ve neer) and an alternative method (dentin adhesive applied to dentin and cure d before taking the impression for the veneer). Results: In the finite elem ent model, the crown compliance increased by a factor of 2.16 after facial enamel removal and returned to 96% of its original value after the placemen t of the veneer. The finite element values showed a good correlation with s train gauge experimental results (one-sample t test, P > 0.35 after facial enamel removal and P > 0.19 after veneer placement). The dentin adhesive ap plication mode was not critical to the recovery of tooth stiffness (analysi s of variance, P = 0.10). However, qualitative scanning electron microscope observations demonstrated that the traditional dentin adhesive application was associated with bonding failures between the hybrid layer and the over lying resin, whereas unbroken and continuous interfaces were obtained with the new method using the same dentin adhesive. Conclusion: The results of t his study definitely Favor the biomimetic behavior of porcelain veneers bon ded to teeth using an optimized application mode of dentin adhesives, becau se this treatment modality proved to restore both the mechanical behavior a nd microstructure of the intact tooth.