Effects of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) application on enamel microhardness after bleaching.

PURPOSE: To evaluate the effect of casein phosphopeptide-amorphous calcium phosphate (CCP-ACP) application on the microhardness of bleached enamel and compare it to that of fluoride application. METHODS: 10 extracted bovine incisors were cut into four sections (4 x 4 x 3 mm) that were randomly distributed among five groups (n = 8). All groups were bleached three times using 38% hydrogen peroxide (HP), with 5-day intervals between bleaching, according to the following treatment protocols: Group A: bleaching only; Group B: bleaching + daily CCP-ACP paste; Group C: bleaching + daily casein phosphopeptide-amorphous calcium fluoride phosphate (CPP-ACPF) paste; Group D: bleaching + daily 250ppm NaF solution; Group E: bleaching + APF gel (once after final bleaching). Specimens were maintained in artificial saliva throughout the experiment. Baseline and post-treatment Vickers microhardness values were obtained for all specimens. Statistical analysis was performed using one-way ANOVA and post-hoc Tukey tests. RESULTS: Groups B and C showed significant increases in enamel microhardness following treatment (P < 0.001), whereas no statistically significant changes were observed in Groups A, D, or E (P > 0.05). One-way ANOVA of delta Vickers microhardness numbers (deltaVHN) revealed significant differences among groups (P < 0.001), with Group B showing the highest deltaVHN and Group A the lowest.

Shear bond strengths of different adhesive systems to white mineral trioxide aggregate.

This study was conducted to compare the shear bond strengths of different adhesive systems to White Mineral Trioxide Aggregate (WMTA). To this end, 40 cylindrical acrylic blocks with a hole in the middle measuring 4 mm diameter x 2 mm height were prepared. The hole was filled with WMTA, and the specimens were allocated into four groups: Group 1--Prime & Bond NT; Group 2--AdheSE; Group 3--Xeno III; and Group 4--Adper Prompt L-Pop. In each group, a different adhesive system and a compomer (Dyract AP) were applied over WMTA. Shear bond strengths were measured using a universal testing machine, and then the data were subjected to one-way ANOVA and Scheffé's post hoc test (p<0.05). Significantly lowest shear bond strength value was obtained with Adper Prompt L-Pop, whereas Prime & Bond NT revealed higher shear bond strength than the others (p<0.05). In conclusion, an etch-and-rinse adhesive system--which exhibited significantly higher shear bond strength than self-etch adhesive systems--could be a preferred choice when placing compomer materials upon WMTA.

Evaluation of survival of 3 different fixed space maintainers.

PURPOSE: The purpose of this study was to provide a comparative evaluation of the survival times and failure rates of different types of fixed space maintainers (SMs). METHODS: A total of 30 4- to 10-year-olds were selected for the study. Children were divided into 3 groups, according to type of SM, namely: band and loop (B&L), direct bonded (DB), and fiber-reinforced composite (FRC). Patients were recalled once every 3 months for clinical evaluation for 1 year or until failure. The survival times of SMs were estimated by means of the Kaplan-Meier method, and confounding factors were investigated using Cox regression analysis. RESULTS: Mean survival time was highest for B&L SMs (11.20 months), followed by DB SMs (9.20 months) and FRC SMs (6.70 months). There were statistically significant differences noted between types of SMs (log rank=11.99; P=.002). The Cox proportional hazards model revealed that age, sex, dental arch, and side of the jaw were not significantly correlated with "success of SMs" (P>.05). CONCLUSIONS: Band and loop fixed space maintainers showed superior performance in terms of both survival time and success rates versus direct bonded and fiber-reinforced composite space maintainers.

The evaluation of bond strength of a composite and a compomer to white mineral trioxide aggregate with two different bonding systems.

The purpose of this study was to evaluate the bond strength of a resin composite and a polyacid modified composite or "compomer" to white mineral trioxide aggregate (WMTA) with two different bonding systems (total-etch one bottle and self-etch one step). Forty specimens of WMTA were prepared and divided into four groups. In group one, Single Bond (3M/ESPE, St Paul, MN) and Z250 (3M/ESPE) were placed over WMTA. In group two, Prompt L-Pop (3M Dental Products, St Paul, MN) and Z250 were applied. In group three, Single Bond was applied with Dyract AP (Dentsply DeTrey, Konstanz, Germany), and, in group four, Prompt L-Pop was applied with Dyract AP. The shear bond strength was measured, and the fractured surfaces were examined. The results of the shear bond strength tests were analyzed by one-way analysis of variance test. The results of this study have suggested that the total-etch one-bottle adhesive system mediated a stronger bond to WMTA for both the resin composite and the compomer investigated. The placement of composite (Z250) and compomer materials (Dyract AP), used with total-etch one-bottle adhesive (Single Bond), over WMTA as final restoration may be appropriate.