Bond strength of CAD-CAM and conventional veneering materials to different frameworks.

ABSTRACT

STATEMENT OF PROBLEM: New materials and precise manufacturing processes allow for new processes in the veneering and production of fixed dental prostheses. However, data on the bond strength of computer-aided design and computer-aided manufacturing (CAD-CAM) and conventional veneering materials to substrates bonded with different composite resins are lacking. PURPOSE: The purpose of this in vitro study was to investigate the shear bond strength (SBS) of 2 CAD-CAM, Lava Ultimate (LVU) and VITABLOCS Mark II (VMII), and 3 conventional veneering materials (VM9, VM13, VTI) to 3 different substrates zirconia (ZIR), cobalt-chromium (CC), and titanium (TIT). MATERIAL AND METHODS: Substrates and veneering cylinders were manufactured and bonded by using 3 different composite resins, RelyX Unicem (RUL), RelyX Ultimate (RXU), and Sinfony (SIN), after various pretreatments (n=18). Half the specimens underwent artificial aging before SBS testing, and failure types were analyzed. Univariate 1-way ANOVA, Kruskal-Wallis, and Mann-Whitney U were computed (α=.05). RESULTS: CC substrates bonded with RUL showed the highest SBS (P=.007). ZIR substrates bonded with RXU presented higher SBS than TIT substrates (P=.007). ZIR substrates bonded with SIN showed higher SBS than CC substrates (P<.001). SIN veneered groups showed lower SBS than that observed for VM9/13/VTI (P<.001). SIN veneered LVU and VMII substrates presented lower SBS (P<.001). Thermocycling led to a reduction in SBS for most groups (P=.001-.022). SIN veneered substrates and RXU veneered VMII substrates resulted in lower SBS than that seen for VM9/13/VTI and veneered ZIR substrates bonded with SIN or RXU (P<.001). Adhesive failures were most common. CONCLUSIONS: While RUL is capable of forming a stable bond to CC without pretreatment, ZIR substrates achieve higher SBS after conditioning with an MDP-containing primer when using RXU or SIN than that seen for RUL. Pretreated CAD-CAM-veneered ZIR substrates bonded with SIN or RXU led to similar SBS results to those observed for conventional veneers, while veneering with SIN resulted in lower SBS.