Effect of Tannic Acid on Bond Strength of Etch and Rinse and Self-etch Adhesive Systems in Dentin of Primary Teeth.

INTRODUCTION: One of the possible mechanisms for the gradual destruction of bond strength in dentin-resin interface, could be due to the demineralized unstable collagen matrix. Use of protease inhibitors, such as tannic acid (TA) could prevent destruction of collagen fibers. The aim of this study was to compare the TA effect on bond strength of etch and rinse and self-etch adhesive systems in the dentin of primary teeth.

MATERIALS AND METHODS: This in vitro study was done on 40 extracted primary molar teeth. The teeth were sectioned in the mesiodistal direction, and enamel of buccal and lingual surfaces was removed. Samples were randomly divided into four groups: Single bond (SB) + TA, SB, Clearfil SE Bond (CSB) + TA, and CSB. Then, Z250 and Clearfil AP-X composites were cured on the surfaces of SB and CSB groups respectively. After that, all samples were divided into aging and non-aging groups. For 3 months, samples were placed under 1,000 thermal cycles in aging group. Subsequently, the shear bond strengths of all groups were measured by the International testing machine, and failure mode was evaluated by an optical stereomicroscope. Data were analyzed with paired t-test and independent t-test.

RESULTS: Tannic acid induced a significant reduction in the immediate bond strength of adhesive SB. Meanwhile, TA had no significant effect on shear bond strength of the CSB system.

CONCLUSION: Based on our findings, use of TA is not recommended with SB and CSB adhesives on primary teeth.

CLINICAL SIGNIFICANCE: Tannic acid may not be considered in resin restorations of primary teeth.