Storage effect of a pre-activated silane on the resin to ceramic bond

Objectives. The purpose of this study was to investigate the process of hydrolysis and chemical stability of a pre-activated silane solution stored for different periods of time. The tensile bond strength of resin composite to ceramic was also evaluated in order to determine the functional effectiveness after storage of the pre-activated silane solutions. Methods. Silane solutions using γ-methacryloxypropyltrimethoxysilane (γ-MPTS), acetic acid and ethanol were freshly prepared and kept for 15 min, 2 h, 24 h, 1 week, 1 month, 6 months, and 1 year. The solutions were analyzed using a 2000 Perkin–Elmer Fourier transform infrared (FT-IR) spectrophotometer. For the tensile bond strength test, Ni/Cr rods were prepared with ceramic facings polished to 1 μm. Five groups of ceramic surfaces (n=60) were treated with the pre-activated silane solutions and bonded using a luting resin. The process used to prepare the surfaces prior to bonding consisted of removing unreacted silane by boiling water and then heat treatment. Each group was then subdivided into two groups (n=30) and stored under two different storage conditions before subjecting to the tensile bond strength test; either (1) dry at room temperature for 24 h or (2) boiling water for 24 h. Results. FT-IR analysis showed that nearly complete hydrolysis of γ-MPTS has occurred 24 h after mixing, followed more slowly by the formation of siloxane (Si–O–Si) oligomers. The bond strength test results showed that there was no statistically significant difference in the mean tensile bond strength for any of the groups either in dry condition or in boiling water (P>0.05). The mode of failure for all groups was predominantly cohesive failure within the resin. The silane bond was also capable of resisting hydrolytic attack in boiling water for all the groups. Significance. From the results of this study it can be concluded that, when using an appropriate silane application technique, the adhesive effectiveness of a pre-activated silane solution based on γ-MPTS, acetic acid and ethanol will not deteriorate when stored for up to 1 year at room temperature.