51 - Bonding Durability of Resin Cement to Lithium Disilicate Glass Ceramics

Abstract

To obtain reliable adhesion of resin cement to glass ceramics, it is generally known that it is important to apply a silane coupling agent to glass ceramics surface to make its surface has chemically bonding ability. Currently, there are several types of commercial resin cement system with different approach to provide silane coupling agent, such as, prosthesis primer, mixed in bonding agent, or compounded in cement paste. The purpose of this study is to evaluate the bond durability of several resin cement systems to lithium disilicate glass ceramics (LDS) to find reliable system with silane coupling ability. 3 resin cement systems, G-CEM ONE (GO, GC Corporation) with G-Multi Primer (GMP, GC Corporation) which is prosthesis primer included silane coupling agent, PANAVIA SA Cement Universal (PSU, Kuraray) which compounded silane coupling agent in cement paste, and RelyX Universal (RXU, 3 M) with Scotchbond Universal Plus Adhesive(SBU+, 3 M) which is bonding agent mixed silane coupling agent in it were examined. Initial LiSi Block (LiSi, GC Corporation) was used as LDS in this study. LiSi were embedded with acrylic resin. Adhesive surface was finished with 600-grit SiC paper (#600) or hydrofluoric acid (HF)[BISCO PORCELAIN ETCHANT 9.5% HF]. Bonding area(3.0mm-diameter) and cement thickness(0.1mm-thickness) were defined by plastic-tape. Stainless-steel rod was bonded against the bonding area by each resin cement system according to manufacturers instruction in self-curing mode. Bonded specimens were stored in 37 C distilled water for 24 hours(24 h). In case of thermocycling, they were placed under thermocycling condition(5-55 C for 5000cycles:TC5000). Shear Bond strength was tested with universal test equipment (SHIMADZU AG-IC, crosshead-speed 1 mm/min, N=5). Data were statistically analyzed by Tukey-Krame. In case of GO with GMP, there were no significant differences of SBS between 24 h and TC5000 regardless of surface finish (#600 and HF). On the other hand, in case of PSU and RXU with SBU+, SBS of TC5000 on surface finish of #600 significantly decreased compared with SBS of 24 h. From the results, GO with GMP showed high bond strength and bonding durability regardless of surface finish. In case of #600, its finished surface was relatively smooth and mechanical retention would not be expected, but GO with GMP showed the equivalent bonding durability on #600 compared with HF. It might indicate silane coupling ability in GMP was properly functioned and separate prosthesis primer system can be effective. It is expected that better long term bonding durability to lithium disilicate glass ceramics may be achieved by G-CEM ONE system.