Quintessence International, 01/1993

This paper, in three parts, describes additional modified rubber dam utilizations that are generally not attempted with restrictive orthodox application methods. Part II covers alternative means of retention, with the emphasis on nuisance-free and easy application, during the preparatory, impression, and cementation phases of cast restorations.

Treatment of cervical carious lesions presents significant problems to the restorative dentist, including difficulties with access and with the restorative materials themselves. Conventional approaches are not suitable for inaccessible or multisurface cervical lesions. Polymerization shrinkage associated with composite resins is also a problem. Although indirect composite resin inlay techniques address these shortcomings, they generally require two patient visits. An improved technique solves these problems by utilizing a copper basnd impression technique, a quick-setting stone die, extraoral curing of the composite resin inlay, and dentinal adhesive bonding technology in a one-visit restorative approach to the cervical carious lesion.

Gelfoam biodegradable mesh was used in the surgical treatmen of an infrabony defect in a 30-year-old patient. A similar defect in the same patient was treated in the same way, but the mesh was not placed. The soft tissue of the site that received the mesh healed faster, with regeneration of normal anatomy and keratinized epithelium, minimal soft tissue recession, and reduced postoperative crevice depths. The simple clinical placement technqiue and the complete resorption of the material, which obviates the need for a secondary surgical procedure for removal of the material, are advantages over the currently used nondegradable materials. Further work is required to establish whether this material has the potential to be used routinely in surgical regeneration procedures.

Historically, cast gold occlusal surfaces for complete or removable partial dentures have been fabricated with retentive loops or beads and luted to prepared denture teeth with acrylic resin or attached to tooth-colored, heat-processed acrylic resin. At present, alterantives to mechanical retention for attaching resin to metal include chemical bonding of the resin after placement of intermediate ceramic or tin layers and the use of chemically adhesive resin cements. Compared to mechanical retention, the chemical bonding of resin to metal requires less gold and allows more room for properly contoured and esthetic resin. Additionally, this chemical bond limits microleakage at the resin-metal interface. In the following technique, cast gold occlusal surfaces are fitted to onlay preparations of acrylic resin denture teeth set in a processed denture base. The castings are air-abraded, tin plated, and luted to the denture teeth with Panavia dental adhesive. This method is quick, easy, and economical.

An indirect technique for taking hydrocolloid impressions of multirooted teeth is described. Advantages of both hydrocolloid impression material and the technique are discussed.

The purpose of this investigation was to evaluate the effect of three 10% carbamide peroxide bleaching agents on enamel microhardness and surface morphology. Seventy-two enamel slabs were subjected to one of three carbamide peroxide solutions or an artificial saliva solution for 15 hours a day for 2- and 4-week periods. During the remaining 9 hours, slabs were exposed to human saliva in vivo. Although differences were not statistically significant, microhardness values of all treated specimens 2 weeks after treatment were less than those of control specimens. These trends, however, were not evident at 4 weeks. Scanning electron microscopic evaluation revealed significant surface alterations in enamel topography for slabs treated with the bleaching solutions for 4 weeks. The most severe alterations were found in slabs exposed to the lower-pH solutions.

Little is known about the oral health of American blacks. In particular, have they experienced the same reductions in dental caries and improvements

An ideal prophylaxis paste should have both cleaning and polishing properties. Key elements would be abrasive particles that become less agressive under load. The abrasive perlite, a volcanic glass with a sheetlike gemoetry, is claimed to have these unique properties. This study evaluated the average particle size, size distribution, and morphology of perlite in raw form, in an unused prophylaxis paste, and a used prophylaxis paste. The su rface roughness induced on enamel and dentinal specimens was quantitated after paste application in either a rubber cup or a nylon brush. Flour of pumice, a standard prophylaxis paste, a polishing paste, and water were tested similarly. The luster induced by the tested pastes and controls was assessed. Perlite blunted and disintegrated under load. The perlite-containing prophylaxis paste acted as a fine or superfine prophylaxis paste, although it was ranked as medium, based on the mean particle size of its abrasive in the fresh, unused form. Perlite might provide the properties required for the abrasive material of an ideal prophylaxis paste.

The purpose of this study was to compare the in vitro microleakage of a new dentinal bonding system, not yet released in the United States, to the microleakage of two first-generation bonding agents. Simulated Class V cavities were prepared in freshly extracted bovine incisors and restored with the appropriate composite resin-bonding agent combination. Restorations were thermocycled and examined for microleakage at 24 hours and 60 days. Comparison of the materials revealed no statistically significant difference in microleakage scores at the gingival or incisal margins after 24 hours. However, the first-generation bonding agents exhibited significantly more microleakage at the gingival margin than did the new bonding system after 60 days. No significant increase in microleakage was measured at the incisal margin for any of the materials after 60 days. In contrast, all materials exhibited a significant increase in leakage at the gingival margin after 60 days. No correlation between microleakage and polymerization shrinkage or coefficients of thermal expansion of the composite resins could be established.