Quintessence International, 12/1996

A number of practical problems may be encountered when a dentist attempts to provisionalize an indirect restoration. Problems that relate to provisional restorations for conservative, less retentive, ceramic cavity forms are discussed. A provisionalization technique that improves marginal integrity, assures predictable retention, and facilitates cleanup following detachment is introduced.

A clinical recall was conducted for 103 patients who were functioning with resin-bonded restorations for approximately 10 years. The purpose of this study was to evaluate marginal adaptation of the cast metal retainers. Following clinical evaluations, replicas of incisal and occlusal margins were examined in the scanning electron microscope to determine marginal separation and microscopic patterns of the resin composite interface between metal and tooth. Anterior abutments exhibited better clinical adaptation and fewer voids and debonds than di d posterior abutments. Larger microscopic marginal separations were associated with those retainers that had clinically detectable voids or defects.

Removable partial denture production in Scotland was studied by analyzing photographs taken of consecutive casts and dentures and reviewing prescriptions of 539 cases at a large dental laboratory. Of the casts, 70.4% were maxillary and 29.6% mandibular. The mean number of teeth present was 9.9 in the maxilla and 8.4 in the mandible. Of the partial dentures studied, 33.6% were acrylate dentures without any framework. None of these had occlusal rests, and 5.6% had clasps. Of the framework-retained maxillary dentures, the palatal strap (12.9%), horseshoe (15.5%), and anterior palatal bar (18.9%) designs were the most frequent. In the mandible, lingual bars (32.7%) and lingual plates (32.7%) predominated. Of the acrylic dentures, 89.3% were made without any instruction from the dentist. The corresponding figure for prostheses with cobalt-chromium frameworks was 15.0%.

The presence of calculus was assessed on the lingual surfaces of the mandibular anterior teeth in a randomly selected group of 63 young adults. The rate of regrowth of calculus after professional prophylaxis was also observed. Twenty-two individuals had supragingival calculus on the mandibular lingual surfaces of their teeth at baseline. Eleven of these individuals demonstrated regrowth of calculus by the end of the study, in spite of repeated professional prophylaxis. Thus, 17.5% of subjects exhibited rapid regrowth of calculus on the mandibular lingual surfaces of their teeth within 2 weeks of professional prophylaxis.

The efficiency of the Cerec 2 system, introduced in September 1994, is briefly presented. The system provides improved accuracy of fit, an automatically generated occlusion, free (unrestricted) cavity design, unlimited anatomic veneer preparation with incisal edge coverage, and automated and simplified operation.

This article presents the long-term follow-up of a patient in whom an incisor that had been fractured through the pulp was replaced with the original tooth fragment. In the replacement process, the enamel, dentin, and pulp were acid etched and bonded as part of the restoration protocol. More than 5 years have passed since the original treatment, and the treatment has thus far been a success.

The purpose of this study was to establish the influence that finishing and polishing of existing amalgam restorations might have on the decision to replace them. Forty extracted teeth, in which amalgam restorations had been placed in vivo, were individually examined by 60 practitioners and students prior to and following standard finishing and polishing procedures. Examiners, who had not been informed of the study's methodology or objectives, opted either for maintaining or replacing the restoration in question. The main reasons for replacement were also registered. Finishing and polishing significantly reduced the number of decisions to replace restorations in all groups and for all practitioners. Appearance (anatomic shape) was the most frequently cited reason for replacing restorations before finishing and polishing, followed by marginal defects and secondary caries.

This in vitro study investigated the temperature changes experienced during electric welding of titanium to determine if the welding heat presented a potential danger to pulpal vitality. Welds were applied to cast titanium simulations of a three-unit fixed partial denture containing two thermocouples measuring temperature changes. Mean maximal temperature changes were 127.4 degrees F near the weld and 68.6 degrees F at the axial wall. The mean times for the temperature to drop to within 10.0 degrees F of starting temperature ranged from 84.1 to 133.7 seconds. The relatively low temperatures recorded in this study suggest that further investigation is warranted into the use of the welder intraorally.