Objective: The purpose of this study was to determine the effect of three different calcium hydroxide (CH) bases placed under composite resins on micro tensile bond strength (µTBS) of a self-etch bonding system.
Methods: Twenty deep coronal dentin surfaces were obtained from sound human molars with a diamond bur using a slow-speed turbine. The teeth were randomly divided into four groups of five teeth. The CH bases used in this study were resin based CH, Kerr-life and Alkaliner. Three groups were treated with one of the calcium hydroxide bases according to the manufacturer's instructions and the fourth group was left uncovered and served as the control group. Bonding system (Clearfil SE bond (CSE)) was applied according to manufacturer's instructions and followed by composite application (Majesty posterior). After the storage in water at 37° C for 24 hours, the teeth were sectioned to obtain several bonded sticks of 1.0mm2 of cross sectional area. The specimens were then subjected to the µTBS test. µTBS values were calculated in MPa (n=15). Fracture analysis of the bonded enamel surface was performed using stereo microscope.
Groups | n | Mean± SD |
Resin based CH | 15 | 24,83±7,16a |
Kerr life | 15 | 21,85±4,57b |
Alkaliner | 15 | 21,80±6,02b |
Control | 15 | 30,19±8,04a |
Results: µTBS were analyzed by One way ANOVA, Post Hoc Tukey tests and showed in the table below. Means with the same letter are not statistically different at p>0.05. µTBS of CSE significantly changed according to used some CH bases (p>0.05). Kerr-life and Alkaliner showed the lowest bond strength to dentin surface (p>0.05). There was not statistically difference between resin based CH and control groups. fracture analysis of the surfaces showed that the failure was mostly adhesive in nature. Conclusions: The resin based CH placed under composite resins dramatically affected the µTBS of CSE to dentin (p>0.05).