In-vivo bond-strength of self-etch adhesive in dentine class I cavities

Objectives: This study evaluated the six-month in-vivo dentin bond strength performance of self-etch adhesives. Methods: Class I cavities (4x7x4mm) were prepared in caries-free human third-molars (n=25). Bonding procedures were performed using two self-adhesive systems (Easy One (EO) and Silorane (S), 3M ESPE) according to manufacturers' instructions. Methacrylate-based composite resin (Filtek Z350, 3M ESPE) was applied using an oblique incremental technique for Easy One Groups. Silorane-based composite resin (Filtek Silorane, 3M ESPE) was inserted using a horizontal 2mm incremental technique. Light-cure procedures were performed using a LED unit (1250mW/cm2). Teeth were extracted after one week (EO n=5; S n=7) and six months (EO n=7, S n=6). After 24 hours in 2% gluteraldehyde storage (4o C), each tooth was horizontally and vertically cut to obtain five bonded beams (0.8 ± 0.1mm2 in cross-section). Specimens were tested in tension using a universal testing machine (Instron) at a cross-speed of 0.5mm/min. Fracture modes were observed under SEM. Data was analyzed by ANOVA and Tukey's test (p≤0.05). Results:(Mean MPa±S.D.) Easy One (1 week= 21.4±6.6; 6 months=17.6±4.3) and Silorane (1 week= 20.0±9.2; 6 months= 13.3± 5.0). No statistically significant values were observed between adhesives in both experimental periods tested. Fracture pattern analysis in SEM revealed predominance of cohesive adhesive fractures for both self-etch adhesives. Conclusions: In vivo results indicate that two new self-etch adhesives bond strength values were not altered after six months in the buccal environment.