Effect of Demineralisation on Bond Strengths of Self-conditioning Dentin Adhesives

Objectives: The purpose of this study was to determine the influence of experimental demineralization on microtensile bond strengths of three different self-conditioning adhesive systems (Adper, AdheSE, Clearfil Protect Bond). Methods: Seventy-two freshly extracted third molars were included. All teeth were specially prepared allowing the simulation of dentin perfusion. Dentin specimens with a total thickness of 3.5 mm were obtained under standardized conditions. The specimens were randomly assigned to six experimental groups. In three groups (AD, BD, CD) the prepared dentin surface was demineralized using acified gel technique (HEC, pH 4.8, 37°C) for 14 days. Group A, AD: Adper; group B, BD: AdheSE; group C, CD: Clearfil Protect Bond. All materials were applied on a standardized surface area as recommended by the manufacturer. Microtensile bond strength (µ-TBS) of the above mentioned adhesive systems was measured 15 minutes after application and light curing of the composite material (Clearfil APX, colour A2) using an universal testing machine. Statistical analysis was performed using SPSS 10.0. Results: For the six test series following microtensile bond strengths were evaluated (mean value and standard deviation in MPa): group A 21.93 (± 3.19), group AD 11.39 (± 5.58), group B 17.65(± 5.50), group BD 5.75 (± 2.35), group C 21.99 (± 3.56) and group CD 15.09 (± 7.26). Statistical analysis showed a significant influence of the used dentin bonding agent on tensile bond strength (pConclusions: Regarding the limitations of an in vitro study it can be concluded that demineralization of dentin might decrease bond strength of self-conditioning dentin adhesives. Keywords: demineralisation, bond strength, dentin adhesive