Quintessence International

A new radiopaque composite resin restorative material was tested for biologic compatibility, clinical performance, and micromorphologic characteristics. Application of the test material to the dental pulp of rat incisors did not result in any toxic reaction, even when the pulp was covered by only a thin layer of dentin. A 3-year clinical test of the material in humans led to acceptable results in Class I, III, IV, and V cavities. On average, only 10% of the restorations had to be replaced within the test period (Class V restorations had to be replaced at a rate of 15%). The micromorphologic observations confirmed the clinical acceptability of the material, despite progressive changes in the surface substance and marginal conditions.

To assess the resistance to fracture of ceramic inlays, extracted sound human molars were restored with different ceramic materials and glass-ionomer or composite resin luting cement. Compression forces were applied to the specimens until they fractured, and maximal force developed, extent and location of fractures, and the micromorphology of the fractured surfaces were studied. Inlays made of Vitadur N with aluminum oxide profile and bonded with composite resin demonstrated the highest resistance among the restorative combinations, but their resistance was still lower than that of intact (control) teeth. The extent of fracture increased proportionally to the fracture resistance of the specimens. Scanning electron microscopic observation confirmed the effectiveness of the adhesion between composite resin and etched ceramic and the absence of sufficient micromechanical anchoring between glass-ionomer cement and etched ceramic.

A one-step divergent sliding post incorporated through a crown casting provides effective auxiliary retention for the short crown preparation, especially when interocclusal distance is minimal. With this procedure, retention is gained from the residual walls of both the extracoronal preparation and the canal preparation even though their respective axes may be divergent. A tube and screw attachment may also be incorporated inside an understructure coping to secure a permanently cemented short crown-and-bridge retainer. Both techniques may be used separately or in combination for maximal retention and, despite the additional complexity and cost, will compensate for the short extracoronal walls of the second molar preparation.

This case report demonstrates correction of a maxillary anterior diastema in a Class I, deep bite dentition by using an intrusion utility arch wire. With proper case selection, this approach permits a conservative resolution to a common esthetic complaint. Critical treatment criteria, including diagnostic considerations, appliance mechanics, and retention, are discussed.

A recently reported technique for bleaching vital discolored teeth involves the use of a mouthguard and 10% carbamide peroxide without preoperative etching or postoperative polishing of the enamel. This in vitro study evaluated the effects of the bleaching agent on the surface texture of the enamel. Thirty-three extracted teeth were subjected to 10% carbamide peroxide for a period equivalent to 5 weeks of nighttime wear. A control area on each tooth had been covered and sealed. All discolored teeth experienced lightening, but there was no difference in color between the treated and control areas; the color-changing effects apparently extend to portions of the tooth not in direct con tact with the solution. Epoxy replicas of the teeth were examined under a scanning electron microscope. No etching was apparent, and no difference in surface texture between treated and control areas was detected.

Proper use of modern composite resin materials precludes the need to mask Class III restorations behind residual labial enamel. With the use of micromechanical enamel bonding, chemical adhesion to dentin, and traditional mechanical interlocking, visible Class III composite resin restorations that exactly simulate the color and texture of natural enamel surfaces can be placed. Such imperceptible restorations, when performed properly, can last for many years. This paper details a step-by-step procedure for restoring a Class III carious lesion with composite resin, using labial access and a recently introduced dentinal and enamel bonding agent.

Radiovisiography is a rapid, low-dose, digital imaging system that utilizes a small, intraoral sensor in place of radiographic film. Because of these characteristics, it may be particularly suitable for use in endodontics. Consequently radiovisiography and conventional film radiography for the imaging of root canals were compared in vitro. There was no statistically significant difference between the percentage of length of root canal visible on conventional film and that visible on radiovisiographic images. Thus, radiovisiography may be considered to be of equal value to conventional film radiography for the imaging of root canal systems in vitro.

Two hundred fifty-eight teeth severely discolored by tetracycline were treated with an internal bleaching technique. Endodontic treatment was required in all teeth before the walking bleaching procedure could be undertaken. Four years of clinical and radiographic evaluation revealed good esthetic results for all patients. Endodontic procedures were considered to be successful, and not one patient showed external cervical resorption after 4 years. This type of treatment is a valid alternative to porcelain laminate veneers for those teeth that exhibit severe tetracycline discoloration and in which the dental enamel and anatomic crown are intact.

Standards presently used to evaluate the biologic compatibility of dental restorative materials are examined and their inherent shortcomings are noted in this report. Studies citing the alleged effects of dental materials on the pulp are reviewed and compared to new theories, which suggest that the principal cause of pulpal inflammation is bacterial infiltration. Thus, studies that are not able to exclude bacteria as a variable cannot be used to draw conclusions as to the cause of inflammatory changes. This paper presents a proposal to alter the current biocompatibility testing methods to methods that can distinguish between the effects of materials and the effects of bacteria on the pulp.

The in vitro occlusal wear of two recently introduced, small-particle composite resins was evaluated. Twelve disks of each material were opposed by maxillary third molars and subjected to 300,000 masticatory cycles in a servohydraulic model of the human masticatory apparatus. Before and after profiles of the surfaces of both the disks and the teeth were mapped and digitally recorded on magnetic disks. P-50 disks showed significantly (P .05) less volume loss than did Herculite disks. Enamel that opposed P-50 disks showed significantly (P .001) more near than did enamel that opposed Herculite disks.