Effect of saliva contamination and cleansing solutions on the bond strengths of self-etch adhesives to dentin.

PURPOSE: This study determined the effect of saliva contamination and cleansing solutions on microtensile bond strengths of self-etch adhesives to dentin. MATERIALS AND METHODS: Seventy-five human molars were ground flat to expose mid-coronal dentin and randomly assigned to five groups (N = 15): no contamination, saliva contamination without cleansing, saliva and cleansing with water, saliva and cleansing with 2% chlorhexidine, and saliva and cleansing with 5% sodium hypochlorite. One-third of the specimens in each group of 15 were bonded with Adper Prompt L-Pop (all-in-one self-etch adhesive; 3M ESPE, St. Paul, MN, USA), one-third with Adper Easy Bond (all-in-one self-etch adhesive; 3M ESPE), and one-third with Clearfil SE Bond (self-etch primer system; Kuraray America, New York, NY, USA). Specimens were restored with composite and processed for microtensile bond strength testing (5-6 rods/tooth). RESULTS: Mean bond strengths ranged from 17.3 MPa for Adper Prompt L-Pop after water cleansing to 69.3 MPa for Clearfil SE Bond after water cleansing. For all three adhesives, there was no statistically significant difference in bond strengths between the saliva contaminated group, the cleansing groups, and the no contamination groups. CONCLUSIONS: Neither saliva nor the cleansing solutions adversely affected bond strengths of the self-etch adhesive systems.

Effect of finishing instrumentation on the marginal integrity of resin-based composite restorations.

PURPOSE: This study evaluated the effect of the use of different finishing instruments on the marginal integrity of resin composite restorations. MATERIALS AND METHODS: Bovine incisors (N = 75) embedded in epoxy resin had the facial enamel ground and polished to 1200-grit. A standardized cavity (3 x 3 mm, 2 mm deep) was prepared on each specimen and restored with a 2-step total-etch adhesive (Single Bond, 3M ESPE, St. Paul, MN, USA) and a hybrid resin composite (Filtek Z250, 3M ESPE) in a single increment. The restorations were mechanically polished to 1200-grit. Specimens were randomized into different groups (N = 5) according to finishing technique: positive control (1200-grit paper), negative control (regular-grit diamond), fine cross-cut laminated burs, straight-cut laminated burs, spiral-cut laminated burs, and finishing diamonds. The straight-cut burs, spiral-cut burs, and finishing diamonds were tested individually as fine, extra-fine, and ultra-fine, as well as sequentially as a series. A high-speed, water-cooled handpiece under standardized pressure (0.5 N) and time (40 seconds) was used for all finishing procedures. Specimens were processed for scanning electron microscope, and margin gaps were systematically measured. Data were analyzed with one-way analysis of variance and Duncan test. RESULTS: The negative control specimens (course diamond) presented the largest gaps, whereas the positive control specimens (mechanically polished) generated the smallest gaps. No statistically significant difference was noted between the finishing diamonds and the positive control. The negative control exhibited significantly larger gaps when compared with the other finishing instruments. Intermediate results were observed for cross-cut, straight-cut, and spiral-cut laminated burs. Fine, extra-fine and ultra-fine finishing diamonds generated smaller gaps compared with laminated burs, but the differences were not always statistically significant. CONCLUSION: Fine, extra-fine and ultra-fine finishing diamonds used to finish composite restorations generated better marginal integrity when compared with carbides and regular-grit diamonds. CLINICAL SIGNIFICANCE When finishing composite restorations, finishing diamond burs result in better composite margins than carbide laminated burs.