George C. Cho

Tensile bond strength of polyvinyl siloxane impressions bonded to a custom tray as a function of drying time: Part I

Time-dependent bond strength studies of two polyvinyl siloxane impression materials to acrylic resin disks with their respective adhesives were studied to determine the optimal time for maximum bond strength. Six groups were tested with varying adhesive dry times of 0, 7, 15, and 60 minutes and 8 and 24 hours before testing. The results indicated that the bond strength of the adhesive increased at least twofold from time zero to 7 minutes adhesive dry time and peaked at 60 minutes for one of the materials and at 8 hours for the other. Bond strengths increased rapidly to the 15-minute test interval and then seemed to plateau. Both materials exhibited decreased adhesive bond strengths at 24 hours.

Efficient soldering index materials for fixed partial dentures and implant substructures

Multiple-unit fixed partial dentures routinely require an intraoral index to ensure accurate fit. One of the most commonly used materials is Duralay acrylic resin, which has yielded satisfactory clinical results, but one disadvantage has been a prolonged setting time. This study compared the setting times of two autopolymerizing resins, Duralay and G. C. Pattern resin. The dimensional accuracy of these materials was also compared with one light-cured resin, G.C. Unifast light-cure resin. All three materials were suitable to relate castings with clinically acceptable outcomes, and chairside time could be saved with the use of recently introduced indexing materials.

Custom characterization of the provisional restoration

The fabrication of esthetic custom provisional restorations that provide optimum esthetics and function accomplished with minimal chairside time is described. The effects of mamelons, translucency, and incisal haloes are reproduced to mimic natural dentition. The technique is based on a provisional shell that is made in the laboratory and relined intraorally for a more precise fit. In addition, it can be characterized chairside to better satisfy the esthetic demands of the patient. The laboratory-processed shell allows us to attain optimal physical characteristics with auto-polymerizing methylmethacrylate resin.