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Biomedical subjects

R B Mazer

Publications and source records attributed to R B Mazer.

8 recordsLinked to original sources
PubMed1998

Tooth structure loss apical to preparations for fixed partial dentures when using self-limiting burs.

STATEMENT OF PROBLEM: Burs with guide pins may be used to limit the depth of tooth preparation for fixed partial dentures. The effects of guide pins on tooth structure apical to the finish line after tooth preparation for fixed partial dentures has not been recorded. PURPOSE: This in vitro study recorded loss of tooth structure within 1.0 mm apical to the finish line of teeth prepared with straight cylinder and tapered cylinder self-limiting burs and one conventional bur. MATERIAL AND METHODS: Forty-five extracted human teeth were randomly divided into three groups. The facial surface of each tooth was prepared with two types of diamond burs with guide pins and a conventional diamond for the control. The surface was profiled before and after tooth preparation. Profiled surfaces were analyzed and the groups were compared using analysis of variance and the Tukey-Kramer HSD test (alpha = 0.05). RESULTS: No significant difference was recorded between the control group and the group prepared with a round-ended tapered cylinder self-limiting pin. However, there was a statistically significant difference between the control and cylindrical pin groups, and between the two groups prepared with self-limiting diamonds. CONCLUSION: This study revealed abrasion apical to the finish line of the preparation in all groups. The cylindrical guide pin group exhibited the greatest loss of tooth surface.

Analysis of Variance↗
PubMed1992

Degradation of microfilled posterior composite.

The substantial improvement in the chemical, physical and mechanical characteristics of posterior composites has contributed to their increased use in recent years. However, some troubling characteristics of these materials are their susceptibility to wear, marginal leakage, and recurrent caries. Numerous studies have dealt with the wear resistance of posterior composites. Only a few have investigated the mechanisms of failure, particularly those containing submicron-sized fillers. The purpose of this study, therefore, was to analyze the clinical characteristics of a posterior composite to determine the mechanisms responsible for marginal degradation. Using a series of optical standards, it was determined that the generalized wear-rate was linear, averaging 8 microns/year. Furthermore, it was shown that the marginal defect was cohesive in nature and that this type of defect, which is inherent in submicron-type posterior composites, was probably due to tensile fatigue failure.

Acrylic Resins↗
PubMed1992

Clinical microleakage evaluation of a cavity varnish.

This clinical study evaluated the microleakage effectiveness of a cavity varnish when used in combination with two types of amalgam: a spherical particle and a dispersed phase alloy. Calcium hydroxide was utilized as the microleakage detection agent. Copalite showed a reduction in microleakage when it was employed with the spherical particle alloy used in this study. This study clinically demonstrated that Copalite is not totally effective in eliminating microleakage.

Bicuspid↗
PubMed1991

Evaluation of various forms of calcium hydroxide in the monitoring of microleakage.

Calcium hydroxide has been shown to be an effective medium for the in vivo microleakage testing of amalgams. The purpose of this study was to determine the relative effectiveness of several forms of calcium hydroxide in the measurement of this clinical problem. It was also the purpose of this study to determine whether a relationship exists between the pH of the Ca(OH)2 liner and its ability to detect microleakage. Standardized Class V preparations were generated on the buccal surfaces of extracted molars. The axial walls of the preparations were based either with Dycal, Dycal VLC, Pulpdent Liquid, or pure Ca(OH)2. A series of teeth without a calcium hydroxide base served as the negative control. All teeth were restored with a spherical amalgam and kept in de-ionized water. The surfaces of the restorations were then subjected to 20 mL of 2 degrees C water for a period of one min. After three min, a color-indicating pH paper was positioned over the restored area for detection of the presence of hydroxyl ions at the amalgam/tooth interface. Regardless of the form of calcium hydroxide, all indicated extensive microleakage immediately after insertion of the restoration. In all cases, the number of samples generating positive results for leakage decreased over a period of time. The rate of decrease, however, was substantially dependent upon the form of calcium hydroxide used as well as its pH. The reagent grade of Ca(OH)2 generated the greatest percentage of positive results for the longest duration.

Calcium Hydroxide↗
PubMed1990

Effect of surface penetrating sealant on wear rate of posterior composite resins.

Although posterior composite resins have been improved considerably, secondary caries and wear continue to be a major concern. Recent studies suggested that microstructural defects such as voids and microcracks contribute to a weakened surface. The purpose of this study was to evaluate the effect of an experimental surface-penetrating sealant on the wear resistance of a posterior composite resin. At the end of 1 year, the rate of wear of the treated restorations was one-half of those not receiving the surface penetrating sealant.

Bisphenol A-Glycidyl Methacrylate↗