Quintessence International, 03/1991

Acrylic resin record bases made from three commerical resins were processed by water bath curing and by microwave energy. The adaptation of the record bases to a standard cast was measured to determine if there were any statistically significant differences in the fit that could be attributed to the differences in curing methods and the brands of resin. The results indicated a small statistically significant difference in favor of the water bath cure overall, but clinically there were no appreciable differences in the adaptation of the record bases with either curing method or the resins used. The adaptation of artificial dentures made from acrylic resin is clinically acceptable with either microwave curing or the water bath method.

Morphologic variations of dental hard tissue should be recognized and considered during restorative procedures. Overlooking anomalies increases the potential for clinical complications. Amalgam was used erroneously in a patient when the presence of a paramolar structure was overlooked. The clinical complications that resulted from overlooking the anomaly led to restorative, endodontic, and periodontal failures. The present report describes the use of conservative endodontics and a cast restoration, taking into account the rpesence of the paramolar structure, to correct the case.

Two patients were treated with surgical implantation of synthetic, granular, nonporous hydroxylapatite to correct bone defects around dental implants. Ultrastructural examination of biopsy specimens taken several months later showed that the hydroxylapatite material was encapsulated mostly by fibrous connective tissue, without any signs of active inflammation. Osteoid and mature bone were also present in many areas. Under the electron microscope, an electron-dense delimiting band was detected at the interface of the tissue and the material. A polygonal, networklike structure, originating from the electron-dense layer and penetrating into the periphery of the hydroxylapatite granules, was also observed. These findings confirm the results of pervious studies, in which it was hypothesized that the electron-dense structures were of a mucopolysaccaride nature and might prove the close bond between the hydroxylapatite and the tissues.

Two cases of pemphigus vulgaris in which oral lesions were the first signs of the disease are reported. The clinical signs and symptoms, histologic characteristics, and immunohistochemistry are discussed. Early recognition of oral lesions associated with the disease is of the utmost prognostic value. Treatment, which can only be symptomatic, usually consists of a combination of a corticosteroid and immunosuppressive medication. Because side effects may be serious, these medications should be prescribed and monitored by an experienced dermatologist.

As an alternative to a conventional fixed partial denture, a modification of the hybrid resin-bonded bridge was used to compensate for a spatial discrepancy accentuaged by a missing tooth. The proximal margins of the restoration were extended onto the facial surfaces of the abutment teeth to create a partially veneered surface. The abutment teeth wre widened by shifting the embrasure into the edentulous space, thus creating more esthetic proporations.

Shaping and fine working of restorations necessitated by cervical lesions, abrasions at the necks of teeth, or root surface caries can often be arduous to complete. As an example of a facilitated trimming and simplified finishing technique for cervical restorations, the use of tissue-protective finishing diamonds to adapt a Class V Type II glass-polyalkenoate (ionomer) cement restoration is demonstrated. Because of their noncutting guiding tips, these safe-ended diamond instruments can ehlp prevent discontinuous and nonanatomic contouring of restorations. In additiion, these special instruments allow a less traumatic working procedure in areas of marginal gingiva.

A renewed interst in conservative cavity preparations has emerged in recent years. In this paper, a substance-saving cavity preparation for the treatment of small, interproximal carious lesions, the rpeventive Class II preparation, is presented. The indications, the cavity preparation, and the obturation are discussed. The combined use of both amalgam and a light-curing pit and fissure sealant is suggested. Clinically, this type of restoration seems to be acceptable. Nevertheless, more clinical experience and in vitro research regarding this type of restoration is needed.

This study compared the amounts and patterns of fluoride release from 11 commercially available glass-ionomer cements into artificial saliva over an 84-day period. The results indicated that the materials differed in the amount of fluoride released, and that Miracle Mix released the highest cumulative total of fluoride over the test period. Along with old Fuji II, Miracle Mix also released the most fluoride during the last time interval (56 to 84 days). All of the materials released the greatest proportion of their cumulative total fluoride in the first 24 hours after mixing.

Fluoride release from a glass-ionomer cement was measured in vivo during an 8-day period. Maxillary arcylic resin appliances, each carrying four glass-ionomer cement specimens, were worn by four subjects at night. Unstimulated whole saliva samples were collected before the subjects retired to bed (pretreatment samples) and in the morning (posttreatment samples). The average fluoride concentration and saliva flow of pretreatment samples were 31 ± 4 ng/mL and 0.5 ± 0.1 mL/min, respectively. In all subjects there was a statistically significant posttreatment increase (.005 < P < .025) in salivary fluoride concentration. The release of fluoride was nearly constant during the test period.

The potential risks of mercury dissolution from dental amalgam have long been recognized. This study examined the effect of hydrogen ion concentration on the release of mercury from two dental amalgams: an admixed high-copper amalgam and a new tin- and copper-free amalgam. Specimens of each type of amalgam were incubated in citric acid buffer o f pH 2.5 or pH 7.0. Results showed that, for both types of amalgam, specimens incubated at pH 2.5 released stati stically significantly greater (P < .0001) quantities of mercury than did specimens incubated at pH 7.0. Release of mercury from the tin- and copper-free amalgam was also statistically significantly greater (P < .0001) than that of the high-copper amalgam at both pH level

Cavity varnishes are resinous materials used under permanent resotrations to protect dental tissues from marginal leakage and harmful components of the restorative material. These materials are soluble in the fluids of the oral cavity. The purpose of this study was to investigate, in vitro, the degree of solubility of these materials in different solvents over a period of time, to obtain an idea of their effectiveness.