Effect of pre- and postoperative bleaching on marginal effect of leakage of amalgam and composite restorations

Objectives: The aim of this study was to investigate the effect of pre- and postoperative bleaching with 10% carbamide peroxide on marginal leakage of amalgam and resin composite restorations. Method and materials: Three groups were made using 30 extracted, caries-free third molars (n = 10). In the preoperative group, bleaching was performed with 10% carbamide peroxide, followed by the placement of resin composite and amalgam restorations on Class V cavity preparations. In the postoperative group, bleaching was performed after the resin composite and amalgam restorations were fabricated. The third group served as a control in which no bleaching was performed. Dye penetration was used for evaluation of marginal leakage. Results: Chi-square test showed that marginal leakage of resin composite restorations increased in both pre- and postoperatively bleached groups, but marginal leakage of amalgam restorations showed no alterations. Conclusion: Bleaching with carbamide peroxide may alter the marginal leakage of resin composite restorations, but amalgam restorations are not affected adversely in vitro

Determination of fluoride release from light-cured glass-ionomers and a fluoridated composite resin from the viewpoint of curing time

The purpose of this study was to investigate the fluoride releasing pattern of several visible light-curing glass-ionomers and one fluoride-containing filling material, from the viewpoint of curing time. Standardized blocks of Time Line (Caulk-USA), XR-Ionomer (Kerr-USA), Vitrebond (3M-USA) and Heliomolar-Ro (Vivadent-Lichtenstein) were light cured for 20, 40 and 60 s, and then stored in deionized distilled water at 37 degrees C for 24, 48, 72 h and 7 days. The water was changed every day and measurements of the fluoride released from the materials were made daily. The results were compared statistically with the results obtained from Ketac-Bond (Espe-Germany) prepared in the same manner. The levels were highest for the first 24 h; in the following days they decreased rapidly. The fluoride-releasing patterns of all these materials were similar to each other. The fluoride release was the highest from XR-Ionomer, and the lowest from Heliomolar-RO. For Time Line glass-ionomer, the fluoride release from 20 s cured blocks was significantly higher than the fluoride release from 40 and 60 s cured blocks at the end of 1 week. It was observed that the fluoride release from Ketac-Bond was significantly lower than XR-Ionomer and VitreBond and higher than Time Line and Heliomolar-Ro

In vitro plaque formation on some dental filling materials

The purpose of this study was to investigate the effects of filling and lining materials in various compositions on Streptococcus mutans. Five glass-ionomer cements (Vitrebond, XR Ionomer, Ketac-Bond, Shofu Base Cement, Shofu Lining Cement) and two composite materials (Heliomolar-RO, Concise) were used in this study. Samples from these materials were prepared in sterilized conditions and hung in tryptic soy broth medium containing 5% sucrose. The media were inoculated with Streptococcus mutans ATCC 13419. After 5 days, the plaque that had accumulated on the surfaces was scraped off and weighed in wet and dry conditions, Then the colonies were counted and evaluated in comparison with each other. The least amount of plaque and colony numbers were found on Vitrebond material disks, in conclusion, there were no differences among XR Ionomer, Heliomolar-RO and Ketac Bond. Concise gave better results than some materials containing fluoride; whereas the most abundant amounts of plaque were found on Shofu Lining Cement and Shofu Base Cement