Quintessence International, 09/1996

Achievement of an esthetic single-tooth restoration in the anterior segment is a difficult task for the restorative dentist. A case is described in which two congenitally missing maxillary lateral incisors were replaced with single-tooth implants. A new technique was used to restore the teeth provisionally with a polyethylene ribbon and resin replacement. Light-cured staining systems for acrylic resins and ceramics were employed to customize both the provisional and final restorations.

The distribution of stress around implants placed in the first molar region of the mandible was biomechanically analyzed in a two-dimensional mathematical model. Two types of implants, vertical and angled, were subjected to a vertical load of 100 N and a horizontal load of 50 N in turn. The magnitudes and contours of compressive and tensile stress within the surrounding bone were determined. For the sake of comparison, maximal compressive stress and maximal tensile stress at the surrounding bone were calculated. There were no measurable differences in stress values and contours when a horizontal load was applied to the vertical and angled implants. However, with the vertical loading, the compressive stress values were five times higher around the cervical region of the angled implant than around the same area in the vertical implant.

The prosthetic treatment of edentulous glossectomy patients is very difficut. The tongue defect results

Retention of complete mandibular dentures can be successfully achieved by means of an implant-retained or natural tooth-retained bar and clip system in the anterior segment of the mandible. The same design principles hold true for both methods of anchoring the retentive bar. These retentive elements must be constructed to allow some freedom of movement around a fulcrum line designed to be perpendicular to the sagittal plane.

Approximal carious lesions provide unique diagnostic and restorative challenges for clinicians interested in conserving tooth structure. Direct access reduces diagnostic doubt and facilitates optimal restorative management. The direct access afforded to newly erupted posterior teeth provides an imcomparable window of opportunity to the proximal surfaces. Optimal management is limited to the interval between exfoliation and eruption, because access is lost once the erupting adjacent permanent teeth come into contact. Diagnostic and restorative strategies accomplished after creation of direct access to approximal lesions are discussed.

A review of current clinical research has demonstrated that successful attachment with resin-based bonding systems is achieved through brief acidic conditioning of dentin, followed by thorough coverage with resin priming and bonding agents. This article discusses factors of clinical relevance in achieving optimal results. Effective priming, using multiple coats to enhance resin penetration to the full depth of dentinal demineralization, is crucial. A thin, uniform layer of bonding resin is a critical, elastic intermediary for absorbing stresses of polymerization shrinkage. An air stream should be used only for evaporation of solvent and not for spreading bonding resin, because use of an air stream causes uneven thinning of this valuable intermediate layer. Contamination of the dentinal surface with excessive moisture or solvent or the presence of air voids will make bonding unpredictable under clinical conditions. Adequate etching of peripheral enamel continues to be an important factor in the long-term retention of adhesive restorations.

This study was conducted retrospectively to evaluate the clinical performance of preventive resin restorations. Five hundred thirty-two restorations in 351 patients had been in the mouth for a mean of 16.5 ± 7.6 months. The clinical performance was determined with a modified version of the US Public Health Service rating system. In 79.9% of the restorations, the marginal discoloration was rate d as Alfa (no discoloration), while only 0.9% were scored as Charlie (discoloration pernetrating in a pulpal direction). The marginal adaptation was rated as Oscar (fully sealed) in 28.4% of restorations; in only 0.4% of restorations, rated as Charlie or Delta, was the dentin or base exposed. In 98.3% of the restorations evaluated, the anatomic form was rated as Alfa (continuous with existing anatomic form). Recurrent caries was associated with 2.3% of the restorations. Chi-squared tests failed to reveal any statistically significant relationships between the clinical performance of the restorations and the length of time in the mouth.

This investigation compared the initial fluoride release and release following refluoridation of three resin-modified glass-ionomer cements (Photac-Fil Applicap, Vitremer, and Fuji II LC) and a new polyacid-modified resin composite material (Dyract). After daily fluoride release was measured for 8 days, specimens were refluoridated in 1,000-ppm solutions of fluoride ion for 10 minutes and fluoride release was measured for 5 days. Two further 5-day refluoridation-release periods were carried out. All materials released fluoride initially. Photac released the most; Dyract released the least. Initial release was greatest over the first few days. All materials released significantly more fluoride for 24 to 48 hours after refluoridation. Less fluoride was released with each successive refluoridation for the three glass-ionomer cements. The release from the Dyract compomer remained at a comparatively constant and significantly lower level following each refluoridation.

This in vitro study compared the relative radiopacities of three commercially available resin-modified glass-ionomer cements (Vitremer, Fuji II LC, and Photac-Fil), an experimental resin-modified glass-ionomer (V-66), two conventional glass-ionomers (ChemFil and Fuji Cap II), and amalgam (As the control). Radiopacity was assessed densitometrically and expressed as equivalent thicknesses of aluminum. All the glass-ionomer cements were more radiopaque than enamel and dentin, with the exception of ChemFil and Photac-Fil. Apart from the control ma terial, the experimental resin-modified glass-ionomer material, V-66, had the highest radiopacity of all the materials tested. Of the three resin-modified glass-ionomer materials tested, Fuji II LC was the most radiopaque and Photac-Fil the least. For the radiopacity of restorative glass-ionomer materials to exceed that of enamel, it should be greater than 1.5 mm of equivalent thickness of aluminum.