Effects of two methyl methacrylate-tributylborane-based luting agents with a silane-phosphate primer on bonding of four different CAD/CAM resin composite materials.

This study compared the bond strengths of four adhesive systems and four different resin composite block materials: Gradia Block (GR), Shofu Block HC (SH), Estelite Block (ES), and KZR-CAD HR2 (KZ). A primer (PZ-AB) containing a silane (γ-MPTS) with 10-methacryloyloxydecyl dihydrogen phosphate (MDP) was applied to ground surfaces of the resin composite block specimens, and the specimens were then bonded to stainless-steel rods using two methyl methacrylate-tributylborane (MMA-TBB)-based luting agents (SB and MT), designated as the PZ-AB/SB and PZ-AB/MT adhesive systems, respectively. The SB resin contained 4-methacryloyloxyethyl trimellitate anhydride (4-META), whereas the MT resin did not. The SB resin without primer (No primer/SB) and a dual-curing composite-type adhesive system (UPA/RelyX) were used as controls. The 24-h tensile bond strengths were determined and analyzed using the Tukey-Kramer HSD test (α = 0.05, n = 8). The highest bond strengths were obtained for the GR/PZ-AB/MT, GR/PZ-AB/SB, KZ/PZ-AB/MT, ES/PZ-AB/SB, and KZ/No primer/SB groups, whereas the KZ/UPA/RelyX, ES/UPA/RelyX, SH/UPA/RelyX, and SH/No primer/SB groups exhibited the lowest bond strengths. For each resin composite block material primed with γ-MPTS and MDP, the MMA-TBB-based luting agents, irrespective of the presence of 4-META, provided higher bond strengths than the dual-curing composite-type adhesive system.