DENTIN BONDING DURABILITY AND CALCIUM RELEASE PROMOTED BY EXPERIMENTAL ADHESIVE SYSTEMS CONTAINING CALCIUM HYDROXIDE
self-etch adhesives, calcium hydroxide, bond strength
This study aimed to evaluate the impact of adding different levels of calcium hydroxide on the durability of bonding to dentin and the release of calcium from experimental self-etch adhesives systems. Methods: Four adhesives systems were formulated from the components UDMA, HEMA, GDMA-P, TPO, diphenyl iodonium, ethanol and water with different mass fractions of calcium hydroxide: 0% (control), 1%, 2% and 4 %. For the calcium release test, disks (5 mm in diameter x 1 mm in thickness) were made (n = 4) and immersed in distilled water. Calcium concentration was measured after 3h, 24h, 48h, 72h, 96h, 120h, 144h and 168h using a spectrophotometer. To analyze the durability of the dentin bond, 24 third molars (n = 6) were used. The middle third dentin was exposed, the adhesive systems were competent and 2 increments of composite resin and photoactivated. After 24 h of immersion in distilled water, the toothpicks were cut. Half of them were submitted to the bond strength test by micro traction in a universal testing machine (OM-150) and the other half stored in distilled water for 12 months for subsequent assessment of the bond strength. The bond strength data were statistically obtained through the ANOVA 2-factor tests and Tukey's post-test (p <0.05). The eluate pH was analyzed descriptively. In the bond strength test, there were statistically significant differences between storage times (p = 0.001). Only the material containing 2% of calcium highlighted a statistically significant increase in bond strength after 12 months of storage in water. The others maintained statistically similar values between storage times. All adhesive systems released calcium amounts below 1 ppm. Therefore, the inclusion of 2% calcium hydroxide in self-etching adhesive systems is an alternative to increase the longevity of the dentin bond.