Comparison of marginal adaptation between direct and indirect composites.

The evaluation of composite resin as a posterior restorative material has been slow and attended by several problems. Gap formation has been considered a serious problem by many researchers. The purpose of this in vitro study is to compare the marginal adaptation of posterior composite resins placed by a direct method with those placed by an indirect method utilizing flexible dyes. Conclusions drawn from the results of this study are that both techniques produced marginal gaps. Also there were no differences in the width of marginal gaps in the composite resin restorations placed by our direct or indirect methods, and no marginal gap differences were observed as a result of anatomical location.

Toothbrush abrasion caused by different dentifrices.

The purpose of this study was to evaluate the abrasive effect on toothbrush bristles caused by three brands of commercially distributed dentifrices: Colgate regular flavor, Crest tartar-control formula, and Caffree gel. New brushes and brushes tested in distilled water served as controls. Scanning electron micrographs were taken of all test samples, randomly labeled, then presented to independent evaluators. Each bristle evaluated was assigned to one of seven wear categories adapted from previous studies. Crest and Caffree produced the most bristle wear and were not significantly different from each other. Colgate and water resulted in less wear, and new brushes the least wear. These results demonstrate that the effective life of a toothbrush will vary with the type of dentifrice used.