A Randomized Double-blind Clinical Trial of Dentin Surface Treatments for Composite Restorations in Noncarious Cervical Lesions: A 36-month Evaluation.

OBJECTIVE:: This randomized, double-blind clinical trial aimed to evaluate the influence of different dentin surface treatments in noncarious cervical lesions (NCCLs). METHODS AND MATERIALS:: Twenty-nine patients participated in this study. One hundred sixty-five NCCLs were selected and randomly assigned to three groups: G0 (control group) with phosphoric acid etching for 15 seconds; G1: phosphoric acid etching for 30 seconds; and G2: ultrasound probe applied for 30 seconds on the dentin surface. Class V composite resin restorations were performed (Z350, 3M ESPE, St Paul, MN, USA). The restorations were evaluated at baseline and at six, 12, 24, and 36 months according to the World Dental Federation criteria. Survival curves were obtained using the Kaplan-Meier method and the log-rank test. Comparisons between groups and times were performed using the McNemar and Chi-square tests (α =0.05). RESULTS:: The presence of failures due to retention was statistically different among the groups ( p=0.012), and G0 and G2 showed better clinical performance than did G1. Sensitivity decreased over time in all groups. Marginal discoloration, postoperative sensitivity, and marginal adaptation were not different among the groups ( p>0.05). CONCLUSIONS:: The studied dentin surface treatments showed similar clinical performance to the conventional technique at 36 months in terms of marginal discoloration, marginal adaptation, and postoperative sensitivity. In contrast, increased acid-etching time resulted in a higher risk of failure due to retention over time in composite Class V restorations.

Sealing ability, water sorption, solubility and toothbrushing abrasion resistance of temporary filling materials.

AIM: To evaluate marginal seal, water sorption, solubility and loss of mass after brushing of several temporary filling materials. METHODOLOGY: For marginal seal, Class I cavities, including endodontic access preparations, were made in human molar teeth and restored using one or other of several temporary filling materials (n = 10): zinc oxide/calcium sulphate-based cement (Cavit, 3M,ESPE, St. Paul, MN, USA), zinc oxide/eugenol cement (IRM, Dentsply Caulk, Milford, DE, USA), glass ionomer cement (Vidrion R, SSWhite, Rio de Janeiro, RJ, Brazil) or a dimethacrylate-based filling (Bioplic, Biodinâmica, Londrina, PR, Brazil). Dye penetration was assessed after thermocycling and immersion in 0.5% basic fuchsine solution. For water sorption, solubility and loss of mass analyses, disc-shaped specimens were made. Water sorption and solubility were evaluated by mass alteration after storage in distilled water for 7 days (n = 7). Loss of mass was calculated based on the difference of mass after abrasion with a toothbrush (n = 5), and surfaces were analysed by SEM. Data of water sorption, solubility and loss of mass were submitted to anova and Tukey's test, and marginal sealing data to Kruskal-Wallis test (P < 0.05). RESULTS: Statistically significant differences were observed for marginal sealing (P < 0.0001), water sorption (P < 0.01), solubility (P < 0.01) and loss of mass (P < 0.05). Bioplic had the best marginal seal. Cavit had the greatest water sorption and solubility. Vidrion R and Bioplic had the lowest solubility. Loss of mass after brushing was higher for Cavit, followed by Bioplic, IRM and Vidrion R. Cavit and Vidrion R were worn aggressively by brushing. CONCLUSIONS: The resin-based temporary filling Bioplic produced the best marginal seal, and was associated with the lowest water sorption, solubility and loss of mass.

Nanofiller loading level: Influence on selected properties of an adhesive resin.

OBJECTIVES: To evaluate the effect of the filler content in the cohesive strength (sigma), Weibull modulus (m) and degree of conversion (DC) of an experimental adhesive system. METHODS: A HEMA/Bis-GMA/TEGDMA-based adhesive was formulated and filled with silica nanofillers in the following weight percentages (wt%): R0=0%; R1=1%; R3=3%; R5=5% and R10=10%. The adhesive of Adper Scotchbond Multi-Purpose (SBMP) system was used as a commercial reference. Twenty dumbbell-shaped specimens with cross-sectional area of 0.5mm(2) were made per group and tensile tested with a crosshead speed of 0.5mm/min until fracture. The cohesive strength was calculated in MPa. DC was obtained through FTIR after light curing for 25s. Data were submitted to one-way ANOVA and Tukey's test (alpha=0.05) and to Weibull analysis. RESULTS: Mean sigma results were: R0=65.4+/-8.4; R1=73.2+/-8.8; R3=72.0+/-8.4; R5=73.1+/-9.7; R10=85.5+/-13.1 and SBMP=79.0+/-11.0MPa. R10 presented the highest sigma, while R0 showed the lowest. R5 and SBMP did not differ significantly (p<0.05). Weibull analysis revealed no significant difference in structural reliability between groups. The experimental adhesives presented similar results of DC, which, in turn, were significantly higher than the SBMP. CONCLUSIONS: The addition of 10% filler in weight improves the cohesive strength of the adhesive, not interfering in the structural reliability or the degree of conversion.