Tensile bond strength of PMMA- and composite-based CAD/CAM materials to luting cements after different conditioning methods

This study investigated whether the adhesion of novel generation of polymeric CAD/CAM resins to luting cements would improve after use of different conditioning methods, and to evaluate the failure types after debonding. Two CAD/CAM resins (PMMA- and composite-based) were obtained (N=600, n=15 per test group). The specimens were conditioned as follows: MH: Monobond Plus/Heliobond, VL: Visio.link, AM: Ambarino P60, VP: VP connect, CG: no conditioning as control group, and luted with conventional (Variolink II) or self-adhesive luting cement (Clearfil SA Cement). Two types of storage were performed: after 24 h water storage (37 °C) and additional 5000 thermal cycles (5 °C/55 °C). Tensile bond strength (TBS) was measured and data were analysed using 4/1-way ANOVA (Scheffé test), independent two-sample t-test and Chi2 test (alpha=0.05). For both CAD/CAM resins, no or lower bonding was observed for the non-conditioned or AM groups, regardless of the luting cement. The conditioning with MH, VL and VP showed significant increase of TBS. In general, bonding on exp. CAD/CAM composite presented significant higher values compared to PMMA-based artBloc Temp. Variolink II showed higher TBS in combination with artBloc Temp. After conditioning with MH and VL predominantly cohesive failures in the luting cement were observed. All other groups showed adhesive failure. Aging level did not affect the TBS. The bonding properties of the CAD/CAM resin materials are dependent of the targeted selection of the conditioning method and luting cement. Composite-based materials showed higher bonding properties to luting cements than PMMA-based.