Quintessence International, 08/1994

Recent advances in adhesive monomers and surface preparation methods allow strong resin adhesion to all intraoral metal surfaces. Resin-metal bond strengths may exceed typical resin-etched enamel bonds. Innovations in prosthetic procedures have resulted. Data for metal adhesion are reviewed and the use of intraoral metal adhesion to finalize an occlusal rehabilitation is illustrated. Included in the metal surface preparations are intraoral sandblasting and intraoral tin plating.

A simplified technique was used to treat a patient who had limited mouth opening as a result of scleroderma. Treatment included the construction of a three-piece, sectional maxillary partial denture and a one-piece mandibular complete denture.

A new concept for tooth preparation design for complete- and partial-coverage all-ceramic restorations is presented. Because of the efficacy of third-generation dentinal bonding agents, the preparations for complete-coverage and partial-coverage restorations can be made with less emphasis on retentive form. For partial-coverage restorations, cavosurface angles should be large so that the resultant configuration of the enamel rods is conducive to optimal bonding. The new preparations are simple, with extremely tapered axial walls, to allow maximum thickness of the ceramic material. These types of preparations result in finished restorations that are stronger and have better margins and less chance of microleakage. Long-term success of these types of restorations will be determined by the success or failure of the dentinal bonding agent and resin cement system used.

Studies on home-use bleaching agents containing carbamide or hydrogen peroxide demonstrate minimal topographic alteration and insignificant organic change to tooth material. This in vitro study evaluated the effects of a three-step commercial home-use bleaching agent on extracted human incisors over time. Each tooth was digitized by baseline and sequential profilometry and analyzed using computer software. Statistically significant volume loss was evident in cementum and dentin after simulations of 4 and 8 weeks of use.

The purpose of this study was to evaluate the effect on salivary pH of a 10% carbamide peroxide solution when used with a custom-fitted guard for bleaching teeth. Baseline pH values were established for unstimulated saliva and on saliva produced while wearing an empty guard. After insertion of a guard half filled with Proxigel, salivary pH measurements were made at 5-minute intervals until the values returned to baseline levels. Mean salivary pH values were 6.81 ± 0.11 for unstimulated samples and 6.91 ± 0.18 after insertion of the empty guard. After insertion of the filled guard, there was a statistically insignificant decrease in salivary pH during the first 5 minut es, followed by an increase above baseline at 10 minutes, to a mean peak value of 7.32 ± 0.27 at 15 minutes. The difference between the baseline values and the mean peak value at 15 minutes was statistically significant. The results of the study indicated that the pH of saliva increased significantly during the first 15 minutes of nightguard vital bleaching and did not significantly drop below baseline in the first 2 hours after i nsertion with a moderately low-pH solution.

Congenital erythropoietic porphyria is a rare condition resulting from an inborn error in prophyrin metabolism. This deficiency leads to hemolytic anemia, photosensitivity, blistering of the skin, and deposition of red-brown pigments in the bones and teeth. The literature regarding the dental aspects of this disorder is briefly reviewed and the preventive, restorative, and esthetic dental management of a 4-year-old child with congenital erythropoietic porphyria is described.

Contiguous autogenous transplant, also known as the bone-swaging procedure, is a technique aimed at regenerating lost periodontium. Clinical healing of bony defects after bone swaging has been satisfactory, but the relationship and mode of attachment between the bone graft and the root surface have not been fully investigated. A 19-year clinical and radiographic follow-up of a bony defect treated with the bone-swaging technique is presented. A significant coronal increase in bone height and a gain in clinical probing depth were achieved post-surgery and remained unchanged during the first 6 years. The long-term clinical and radiographic findings, however, indicated that the attachment developed at the root-bone interface may not have been a true attachment and may have been more vulnerable to pathogenic local agents. These observations may help the clinician to interpret the clinical and radiographic changes that occur in the area of a bony defect following the use of a bone graft.

An in vivo experiment to determine the wear of restorative materials (gold, ceramic, and microfilled resin) was performed in a patient with bruxism. Telescopic crowns were placed on teeth 35, 36, and 37. The opposing surfaces were all made from ceramic material. The weight loss of the materials was recorded after 30, 60, and 90 days and converted to volume loss. Replicas for scanning electron microscopic studies were obtained. Gold and ceramic material wore equally, while the wear of microfilled resin was two and a half times as much. The ceramic material and the microfilled resin chipped and fractured, but the gold did not. Mainly abrasive and fatigue types of wear were found in all materials.

Ninety patients, with a total of 90 resin-bonded prostheses placed in a private dental office from 1981 to 1991, were recalled for clinical evaluation of their restorations. Tissue condition, patient satisfaction, prosthesis failures by location and by sex of patient were assessed. Debondings occurred in both the mandibular and maxillary arches. In the present study, there were no gender-based differences in the rate of debonding and prostheses with more than two retainers were more likely to have problems.

Microleakage was assessed in Class V composite resin restorations, placed in extracted non-carious human premolar teeth after the enamel cavosurface margins of the preparations had been etched with phosphoric acid for 5, 15, or 30 seconds. The restored teeth were thermocycled, place d in methylene blue dye, invested, and sectioned. The extent of dye penetration along the tooth-restoration interface in the three etching groups was compared. The group etched for 5 seconds showed the greatest leakage; leakage was statistically significantly greater than that in the groups etched for 15 or 30 seconds. The tooth-restoration interface at the occlusal and gingival margins showed more leakage than did the mesial or distal margins.

Extensive silver amalgam restorations in premolars and molars occasionally require sacrifice of healthy unsupported enamel walls or cusps. A posterior composite resin-amalgam compound technique has been proposed to conserve these structures. Microleakage was high at the enamel-amalagam interface, moderate at the composite resin-silver amalgam and dentin-composite resin interfaces, and minimal between the inner enamel and the composite resin. Light microscopy and scanning electron microscopy demonstrated that marginal adaptation of teh silver amalgam to the composite resin of the cusps was acceptable and that penetration of the inner etched enamel to the composite resin was complete.