The effect of HEMA and 10-MDP in the bonding agent of a two-step self-etch system on water sorption, elastic modulus, and microtensile bond strength to dentin.

This study evaluated the effects of HEMA and 10-MDP in the bonding agent in a 2-step self-etch adhesive system, Clearfil SE Bond 2, on water sorption (W) and elastic modulus (E) of the polymerized bonding agent. The microtensile bond strength (µTBS) to dentin was also evaluated initially and after 10,000 thermal cycles (TC10,000). Four bonding agents were tested: the original, H-free (excluding HEMA), M-free (excluding 10-MDP), and HM-free (excluding HEMA and 10-MDP). HEMA increased W and decreased E. Initial µTBS (TC0) was highest for the original and lowest for HM-free. After TC10,000, the original maintained the highest µTBS, indicating the importance of HEMA and 10-MDP. TC10,000 did not reduce µTBS for any groups. HEMA and 10-MDP compromised mechanical property and increased water sorption, suggesting these components could potentially compromise adhesive stability.