Restoration interface microleakage using one total-etch and three self-etch adhesives

This study evaluated the efficacy of a total-etch and three self-etch adhesives in reducing microleakage after three months water storage and thermocycling. Thirty freshly extracted caries-free human premolars and molars were used. Class V standardized preparations were performed on the facial and lingual surfaces, with the gingival margin placed 1 mm below the CEJ. The teeth were randomly divided into four groups; Group I: Xeno III one-step self-etch adhesive (Dentsply/Caulk), Group II: Prime & Bond NT total-etch adhesive (Dentsply/Caulk), Group III: i-Bond one-step self-etch adhesive (Heraeus Kulzer) and Group IV: Clearfil SE Bond two-step self-etch adhesive (Kuraray Medical). The teeth were restored using 2 mm increments of shade A2 resin composite (Esthet-X, Dentsply/Caulk). Each layer was cured using the Spectrum 800 curing light (Dentsply/Caulk) for 20 seconds at 600mW/cm2. The teeth were stored in distilled water for 90 days. Samples were thermocycled 500x between 5 degrees C and 55 degrees C with a dwell time of 30 seconds, then placed in a 0.5% methylene blue dye solution for 24 hours at 37 degrees C. Samples were sectioned longitudinally and evaluated for microleakage at the occlusal and gingival margins under a stereomicroscope at 20x magnification. Dye penetration was scored: 0 = no penetration; 1 = partial dye penetration along the occlusal or gingival wall; 2 = dye penetration along the occlusal or gingival wall; 3 = dye penetration to and along the axial wall. A Mann-Whitney test was used to demonstrate significantly more dye penetration in Group III than in the other groups at both the occlusal and gingival scores (p < 0.0001). When comparing the occlusal and gingival scores for each group, the Wilcoxon Rank test showed no significant difference in dye penetration for Xeno III (p > 0.05), Prime & Bond NT (p = 0.059) and I Bond (p = 0.083), and Clearfil SE Bond yielded more dye penetration at the occlusal than at the gingival wall (p = 0.001).