Quintessence International, 11/1998

Objective: The aim of this in vitro study was to evaluate the shear bond strength to dentin of five different dentin bonding agents in combination with two resin composites (Tetric and Z-100). Method and materials: Human third molars were selected for the study, and cylindrical posts of either Tetric or Z-100 were bonded vertically to a standard flat dentinal area, prepared on the buccal surface of the teeth. A chisel-shaped shearing blade, attached to the crosshead of a universal testing machine, was positioned so that its edge was immediately adjacent to the adhesive joing. The shear bond strengths to dentin of 10 resin composite-dentin adhesive combinations were measured. Results: The results showed that the bond strength of dentin bonding agents may depend on the choice of restorative material. The in vitro bond strength of dentin bonding agents also differed significantly. In several cases, the bond strength exceeded the cohesive strength of dentin. Conclusion: It seems important for clinicians to be acquainted with the variation in bond strength values that is experienced with any bonding system.

This is the first of two articles describing the development and use of a continuous fiber-reinforced composite as a framework for the fabrication of fixed partial dentures and splints. The chemical composition and physical structure of the fiber-reinforced composite, along with the progression and development of a variety of fiber-reinforced composite materials, are discussed. Criteria for case selection, tooth preparation, and the clinical and laboratory procedures required for partial- or complete-coverage fixed partial denture fabrication and delivery are described. Keywords: complete-coverage prosthesis, fiber-reinforeed eomposite, fixed prosthesis, framework, partial-cove rage prosthesis, prei m preg nation

Silver amalgam has become a less attractive dental restorative material for restoration of primary teeth. After many decades of scientific and nonscientific controversy , use of silver amalgam for primary teeth is waning, not because of its mercury content but because dentistry has come up with more suitable materials. This article reviews the development and use of glass-ionomer silver-cermet cements, resin-modified glass-ionomer cements, and polyacid-modified resin composites (compomers) for restoration of primary teeth. Keywords: compomer, glass-ionomer silver-cermet cemenl. polyacid-modified resin composite, primary tooih, resin-moditled glass-ionomer cemenl. silver amalgam

Objective: The purpose of this study was to compare the quanti ties of oral Candida albicans in patients with primary and secondary Sjogren's syndrome before and after the use of orally administered pilocarpine hydrochloride for 1 year. Method and materials: Twelve female subjects with primary (n = 4) and secondary (n = 8) Sjogren's syndrome (mean age ± SEM = 56.7 ± 5.7 years) were enrolled in the study, after meeting rigid enrollment criteria. Oropharyngeal collection of samples and culturing was performed on each subject. Cultures specific for Candida albicans were plated into a culture media tube using the Oricult kit and also by serial dilutions and plating by a streptomycin-vancomycin technique. Cultures were incubated for 48 hours at 37 degrees C. The subjects used 5 mg of pilocarpine hydrochloride, administered orally three times dai ly, for 1 year, after which both of the Candida cultures were repeated. None of the subjects used antifungal medications, none smoked, and all were dentate. Results: There was a significant difference in the prevalence of Candida after the use of pilocarpine hydrochloride for both groups. At the strat of the study, 75% of all subjects were positive for Candida. Following the use of pilocarpine, 25% had positive cultures. There was also a decrease in the prevalence of clinical manifestations of infection from 75% of subjects to 25%. There was a significant decrease in the numbers of Candida cultured following the use of pilocarpine. Conclusion: Long-term administration of pilocarpine hydrochloride resulted in a significant reduction in Candida albicans colonization in patients with primary or secondary Sjogren's syndrome.

The bond strength of resin to metal or ceramic surfaces has been increased with the introduction of various surface-co nditioning techniques. The principles of currently used conditioning methods and clinical trials with these methods are summarized. The advances in surface-conditioning methods have increased bonding to a high level; however, interpretation of the literature review indicates that chemical bonding by means of recently introduced techniques provides better results than does mechanical bonding.

Objective: The purpose of this study was to evaluate the effects of glass-ceramic inserts and different application techniques of resin composites on marginal leakage. Method and materials: Three groups of 10 standardized, round, Class V cavities were prepared on the buccal surface of 30 extracted human molar teeth. Gruop 1 received resin composite restorations, placed in one increment (bulk). Group 2 received resin composite restorations that were placed in two increments, and gruop 3 received resin composite restorations with beta-quartz ceramic inserts. After the teeth were thermocycled and placed in 0.5% basic fuchsin for 24 hours, they were sectioned and examined for microleakage. Results: On the occlusal margins, there was no statistically significant difference between the restorations placed with the incremental technique and the restorations with beta-quartz inserts. The restorations placed with the bulk technique had significantly more microleakage than did the others. On the gingival margins, the restorations with beta-quartz inserts exhibited significantly less microleakage than did the other groups. The restorations placed with the bulk technique showed significantly more dye penetration than did the others. Conclusion: The use of a glass-ceramic insert reduced the marginal leakage of Class V resin composite restorations.

An alternative technique for fabricating resin composite veneers for teeth with color alterations is presented. The technique is based on research carried out with a silica derivative (coesite). The veneer is applied directly to the mouth. The objective of the technique is to provide greater translucence to the teeth, resulting in a better imitation of the natural appearance.

Objective: The purpose of this study was to investigate the effect of conditioners on smear layers produced by different bur types and rotational speeds and to study the interaction of subsequently applied primer and sealer with these conditioned surfaces. Method and materials: Smear layers were produced on human teeth immediately after extraction by burs rotating at approximately 6,000 rpm without water sprary and 400,000 rpm with water sprary. Gluma CPS etchant was applied for 15, 30, and 60 seconds, and a 20% phosphoric acid liquid (control) was applied for 30 seconds to smear layers. The specimens were prepared by critical point drying for scanning electron microscopic imaging within 24 hours. Additional specimens were prepared and treated with Gluma CPS primer and sealer, according to the manufacturer's instructions. Results: There were only small variations in the smear layer thicknesses with different bur types or speeds of rotation. Gluma CPS conditioner, applied for the recommended t imes, did not completely remove the smear layer. An altered smear layer, composed of a reaction product, remained on the dentinal surface. A zone of demineralization did occur, however, beneath the partially removed smear layer in both the 15- and 30-second specimens but was only partly filed by primer and sealer. Smear layers were completely removed by the 20% phosphoric acid liquid to expose a delicate collagen network. Conclusion: An understanding of the appropriate treatment for smear layers is crucialto the development of improved dent in bonding systems.