Microtensile bond strength to dentin of self-etching adhesives after thermociclyng

Objectives: To evaluate the microtensile bond strength (µTBS) to dentin of self-etching adhesives after thermociclyng
Methods: 16 recently extracted caries and restoration free, human molars, were section with a slow speed saw to expose superficial dentin. Self-etching adhesives All Bond Universal (BISCO) and Single Bond Universal (3M ESPE) were place and light-cured over dentin following manufacturer’s instructions, 8 teeth per adhesive. Composite resin (Brilliant, Coltene) was placed over DBA in two increments, light-curing each one for 40 seconds. Specimens were then sectioned to make sticks of 0.9 mm on each side, and 40 sticks were randomly selected among all samples collected from each cement and divided into two groups (n=20), one group was stored in water at 37 C for 30 days, and the other was thermocycled form 5 to 55 degrees with 30 seconds dwell time, for 1000 cycles. Specimens were tested in tensile at 0.1 cm/min until break on an universal testing machine (Tinius Olsen H10K-S). Bond strength was calculated in MPa, data were analyzed with two-way ANOVA calculated at 0.05 significance level. Means were compared using Tukey-Kramer interval also calculated at 0.05 significance level.
Results: Means (Std Dev) are shown in table in MPa. Both adhesives showed almost identical behaivior, both at 30 day storage and after 1000 cycles. There were no statistical difference between adhesives or storage conditions. Both adhesives increased their µTBS after 1000 cycles. Some specimens were broken after thermoclcing but before being tested, those received a value of 0 MPa and increased the variation of the group.
Conclusions: Thermocycling increased µTBS in both self-etch adhesives tested in this study.