Bonding of recent adhesive resin cement to metal-free CAD/CAM milling-blocks

Objectives: The purpose of this study was to examine the bonding efficiency of recent adhesive resin cement systems to various metal-free substrates.
Methods: Three recent adhesive resin cement systems; G-CEM LinkAce (LA; GC), PANAVIA V5 (PV; Kuraray Noritake Dental), RelyX Ultimate (RU; 3M ESPE) and one popular resin cement system; Clearfil Esthetic Cement (EC; Kuraray Noritake Dental, control) were used. Three metal-free milling-blocks for CAD/CAM restoration; two hybrid-resin-composite material; CERASMART (C; GC), VITA ENAMIC (E; VITA), and one feldspathic glass ceramic material; VITABLOCS MarkII (V; VITA), and human sound dentin (D; control) were selected. All substrates were ground with a series of SiC paper up to 800 grit and covered by aluminum-sheet with a hole of 2.4mm-diameter. Each specimen was pretreated according to the manufacturer’s instructions prior to bonding. Cylindrical cured-resin-composite was bonded to the pretreated substrates with four cement systems. Tensile-bond strength (TBS) of the bonded specimens (n=4) were measured. The data were analyzed using two-way ANOVA and Tukey’s q-test.
Results: The mean values of TBS(SD) in MPa with LA/PV/RU/EC were C:5.9(1.6)/3.6(1.3)/ 14.1(2.4)/3.4(1.1), E:14.8(1.2)/13.0(2.0)/15.0(0.7)/10.4(0.8), V:18.0(3.2)/9.4(1.8)/16.1(2.0)/9.3(1.7), D:5.7(2.3)/18.3(3.0)/24.7(4.9)/8.0(2.6). The TBS was influenced significantly by the two factors, cement system and substrate, respectively at p<0.01. The effect of the cement systems on the TBS did vary with the four substrates at p<0.01. The TBS of LA, PV, and RU was statistically greater than that of EC at p<0.01. The TBS to E and V was significantly bigger than the value to C and similar to that to D.
Conclusions: The bonding efficiency of three recent adhesive resin cement systems, LA, PV, RU, to four substrates, C, E, V, D, was significantly superior to that of a popular system, EC. The TBS of the recent cement systems did vary with the bonded substrate.