Objectives: To determine the effect of curing and a new ceramic pre-treatment on the bond strength of composite cements to dentin.
Methods: Feldspathic ceramic blocks were luted to flat bur-cut dentin surfaces using three self-etch composite cements (Nexus 3 (NX3) using Optibond XTR, Kerr; RelyX Ultimate (RXU) using Scotchbond Universal (SBU), 3M ESPE; Panavia F2.0 (PAF) using ED Primer II, Kuraray). Experimental groups included different modes of curing (LL: light-curing of cement and adhesive; LA: light curing of adhesive, auto-cure of cement) and different ceramic pre-treatments: 5% HF (IPS ceramic Etching Gel) + silane (S; Monobond Plus) + Heliobond (HB, all Ivoclar-Vivadent)) or HF+SBU. After water storage (7 days, 37°C), 1x1 mm ceramic-dentin sticks were prepared to determine the micro-tensile bond strength (µTBS).
Results: Regarding composite cement, no significant difference in µTBS was recorded, except for PAF and RXU, the latter when the HF-etched ceramic received SBU that was light-cured while the cement was allowed to auto-cure (p<0.001). Regarding the ceramic pre-treatments HF+S+HB versus HF+SBU, again no significant differences in µTBS were measured for the two self-etch composite cements NX3 and RXU. Regarding the different curing modes, no differences in µTBS were found, except a significantly lower µTBS when solely SBU was light-cured and RXU allowed to auto-cure, and the ceramic received a HF+SBU pre-treatment (p<0.05). Failure analysis revealed predominantly ‘mixed’ failures for NX3. For PAF, the failures were located predominantly at the adhesive-dentin interface. When the ceramic was pre-treated with HF+SBU, failures occurred at the adhesive-ceramic interface.
Conclusion: When the ceramic was pre-treated with HF+S+HB, light-curing of the composite cement was not decisive for the immediate µTBS. Ceramic pre-treatment with SBU decreased the immediate µTBS when the cement was not light-cured.