Abstract
To evaluate the effects of hydrophobic long-chain silane 8-methacryloxyoctyl trimethoxy silane (8-MOTS) on the bonding performance and hydrolytic durability of alumina-abraded zirconia with various luting agents. Zirconia specimens were airborne-particle-abraded with alumina and treated with 1.0% 8-MOTS, 0.5% 8-MOTS, 1.0% 3-(trimethoxysilyl) propyl methacrylate (3-TMSPMA), KATANA Cleaner, or no primers. Three luting agents (G-Cem One, methacryloyloxydecyl dihydrogen phosphate (MDP) only; PANAVIA SA Cement Universal, MDP, and silane; DUO-LINK Universal, without MDP and silane) were used for bonding. An additional DUO-LINK Universal group was treated with Z-Prime Plus. Shear bond strength (SBS) was measured after 24 h of water storage and 16 h of boiling (n = 8 each). Contact angles and debonded surfaces were also evaluated. After boiling, 1.0% 8-MOTS maintained a significantly higher SBS than 1.0% 3-TMSPMA and primer-free conditions in G-Cem One (P = 0.0005). The effect of the external 8-MOTS was limited in PANAVIA SA Cement Universal and DUO-LINK Universal. In DUO-LINK Universal, both Z-Prime Plus and KATANA Cleaner maintained higher residual SBS than the primer-free condition. The high-SBS group generally exhibited more residual luting agents on the zirconia, whereas the low-SBS group predominantly showed exposed zirconia surfaces. The benefit of 8-MOTS was most evident in G-Cem One, in which 1.0% 8-MOTS maintained a higher zirconia bond strength after hydrothermal aging than 3-TMSPMA or no primers. These findings indicate that the effect of 8-MOTS depends on luting agent composition and represents secondary stabilization within a compatible MDP-containing bonding framework.