Influence of methods of application of self-etching adhesive systems on adhesive bond strength to enamel.

PURPOSE: To assess the influence of variations in the application technique of self-etching adhesive systems on the adhesive bond strength to enamel. MATERIALS AND METHODS: One hundred thirty bovine teeth were used and divided into 13 groups. The teeth were embedded in acrylic resin, ground until a flat enamel area was exposed, and polished with 600-grit abrasive paper. The self-etching adhesive systems One Up Bond F, Clearfil SE Bond, Self & Etch were used, and the conventional adhesive Magic Bond and acid etching were used as the control group. One or two layers of the self-etching systems were actively or passively applied. Composite cylinders were made over the bonding area. The samples were submitted to shear bond testing at a speed of 1 mm/min. Statistical analysis of the data was performed using two-way ANOVA, followed by Tukey's test at a 5% level of significance. RESULTS: Significant variations were observed for the factors type of adhesive (p = 0.001, F = 193,3594, df = 3) and application technique (p = 0.001, F = 29,9119, df = 1). No significant interaction was found between the two factors (p = 0.08). The adhesives Clearfil SE Bond and One Up Bond F presented significantly higher adhesive bond strength means than Self & Etch. The active application of two layers resulted in higher bond strength means than the other techniques. CONCLUSION: The application technique had a significant influence on adhesive bond strength to enamel.

Effectiveness of carbamide peroxide and sodium perborate in non-vital discolored teeth

Objective: To evaluate the efficacy of 16% carbamide peroxide gel (CP16%), tetrahydrate sodium perborate (SP) and mixture (CP16% + SP), in walking bleaching of non-vital discolored teeth. Materials and methods: Sixty single-rooted human premolars with intact crowns were used and initial color was assessed using Vita shade guide and standardized photos. The teeth were stained using rabbit fresh blood for 18 days and photos of discolored teeth and color evaluation were performed. The teeth were divided into 4 groups (n= 15), according to bleaching agent used: G1) CP16% gel; G2) CP16% gel + SP; G3) SP + distilled water; G4: control.The bleaching agents were replaced twice at 7-day intervals for 21 days. All teeth were evaluated by two endodontists at days 0, 7, 14 and 21 and the color changes were assessed using Vita shade guide and standardized photos. The results were analyzed byKruskal-Wallis and Dunn’s tests (p=0.05). Results: The experimental groups presented statistically similar bleaching results (p>0.05) at the end of 7, 14 and 21 days. These groups presented significantly higher bleaching efficacy than control group (G4) (p<0.05). The mixture CP16% + SP promoted return of original color in 100% of teeth at the end of 21 days. Conclusion: It was concluded that three bleaching agents were effective in bleaching of stained teeth with blood products, especially at the end of 21 days.

Effectiveness of carbamide peroxide and sodium perborate in non-vital discolored teeth.

OBJECTIVE: To evaluate the efficacy of 16% carbamide peroxide gel (CP16%), tetrahydrate sodium perborate (SP) and mixture (CP16% + SP), in walking bleaching of non-vital discolored teeth. MATERIALS AND METHODS: Sixty single-rooted human premolars with intact crowns were used and initial color was assessed using Vita shade guide and standardized photos. The teeth were stained using rabbit fresh blood for 18 days and photos of discolored teeth and color evaluation were performed. The teeth were divided into 4 groups (n= 15), according to bleaching agent used: G1) CP16% gel; G2) CP16% gel + SP; G3) SP + distilled water; G4: control. The bleaching agents were replaced twice at 7-day intervals for 21 days. All teeth were evaluated by two endodontists at days 0, 7, 14 and 21 and the color changes were assessed using Vita shade guide and standardized photos. The results were analyzed by Kruskal-Wallis and Dunn's tests (p=0.05). RESULTS: The experimental groups presented statistically similar bleaching results (p>0.05) at the end of 7, 14 and 21 days. These groups presented significantly higher bleaching efficacy than control group (G4) (p<0.05). The mixture CP16% + SP promoted return of original color in 100% of teeth at the end of 21 days. CONCLUSION: It was concluded that three bleaching agents were effective in bleaching of stained teeth with blood products, especially at the end of 21 days.