Quintessence International, 11/1993

Experience has shown that a cast restoration will rarely hav proper occlusal contacts. One possible solution could involve the application of a computerized design and fabrication system for restorations with accurately calculated and computer-milled occlusal surfaces. The Cicero system for the production of ceramic-fused-to-metal restorations makes use of optical scanning, nearly net-shaped metal and ceramic sintering, and computer-aided crown fabrication techniques to fabricate restorations with maximal statis and dynamic occlusal contact relations. The Cicero system produces crowns, fixed partial dentures, and inlays with different layers, such as metal and dentin and incisal porcelains, for maximal strength and esthetics. Fabrication of a crown for a mandibular first molar is described to demonstrate the computer-based design system.

Although the corrected or altered cast impression technique is widely taught, it seems to be used very little, in part bec ause it requires separate appointments for framework try-in, corrected cast impression, and occlusal registration. This article describes a technique whereby each of these procedures may be accomplished accurately in one appointment. Visible light-cured resin impression trays with integral occlusion rims are fabricated after the framework has been fitted. Standard procedures are used for the corrected cast impression, and interocclusal records are made with the framework with the impression attached. A stable occlusal registration material allows the interocclusal records to be set aside and used to articulate the corrected cast before the impression tray is separated from the cast. Benefits of this technique include significant time savings, improved accuracy, and simplified procedures.

Fifty-one restorations of the tunnel type were performed wit cermet cement on primary molars. The restorations were assessed clinically, radiographically, and by direct examination of the proximal surface 6 months (group I) and 12 months (group II) after placement. The incidence of fractured marginal ridges was found to be 3.8% in group I and 4.2% in group II. All restorations had their occlusal protion intact and were caries-free. Clinically detectable occlusal wear was found in 7.7% of teeth in group I and 4.2% o f teeth in group II. No correlation was found between direct and radiographic assessment of proximal caries. White sports, without carious penetration, were detected on 53.8% of proximal surfaces at 6 months and on 60.0% of proximal surfaces at 12 months.

With the increasing demand for esthetic posterior restorations, numerous techniques have been developed. The direct resin restoration has probably been used most extensively in Class II situations. Problems with Class II direct resin restoration include difficulty in developing proximal contact, occlusal wear, and polymerization shrinkage. Beta-quartz glass-ceramic inserts have been developed in an attempt to reduce the incidence of these potential problems. They can be placed in a one-appointment technique, are relatively inexpensive, and can readily be utilized by the clinician adept in placing Clas s II composite resin restorations.

Apexification is the accepted procedure to form an apical stop in nonvital teeth with incomplete root formation. A case is presented in which apexification with calcium hydroxide was performed on two permanent central incisors with immature roots and wide-open apices; treatment concluded with gutta-percha root canal restoration. Spontaneous apical seal had probably been initiated before the calcium hydroxide was inserted, but it was weak and nonhomogenous.

The purpose of this study was to compare the accuracy and efficiency of two electronic apex locators to those of a conventional technique of determining working length with radiogjraphs. Data were collected from 53 patients with a total of 96 canals treated by dental students. No significant difference was noted in the accuracy of the two apex locators. The readings from these units exactly agreed with the working lengths established by the students and faculty in 34% of the canals and were within 1.0 mm of the length in 80 to 86% of the canals. The data seem to indicate that apex locators have the potential for reducing the number of radiographs required if used before the working length radiographs are taken. Working lengths should be verified radiographically, because electronic apx locators were not accurate in every case.

Reticulohistiocytic granuloma is a type of reticulohistiocytosis that is manifested without systemic disturbances. A rare case of reticulohistiocytic granuloma presenting as a solitary module on the tongue is reported and discussed.

Long-span, permanently cemented, multiunit prostheses that suffer a fracture of one of the porcelain facings present difficult and often embarassing problems to the clinician. Silane coupling repair systems, although quick, simple, and inexpensive, do not ensure a long-lasting result. An alterantive technique involving use of a porcelain-fused-to-metal overcasting and composite resin cement is presented. The overcasting is luted to the original metal casting.

The role of human saliva has traditionally been considered to be to aid in digestion. However, saliva's major role is not digestion but the protection and maintenance of the alimentary canal, espcially the oral cavity. Loss of salivary flow may be devastating to a patient. Simple tasks such as speaking, chewing, and swallowing may become arduous and uncomfortable. Oral infections and mucosal irritations may drastically affect the patient's systemic and oral well-being. Plaque-mediated diseases and fungal infections may prevail in teha bsence of saliva. Understanding the functions of saliva and recognizing signs and symptoms of salivary dysfunction will allow increased evaluation and awareness of the salivary-distressed patient.

Many methods of bleaching teeth and their effects on the surrounding tissues and pulp have been reported. The effect of bleaching agents on the enamel surface has received some investigation, but the products selected for the present study have not been included in previous scanning electron microscopic studies. In vitro scanning electron microscopic evaluation revealeld that the enamel surf ace underwent considerable changes after 1 hour of exposure to one of four bleaching agents. These changes increased in direct relation to the length of time that the enamel surface was exposed to the oxygenation (bleaching) agent.