Effects of etching and adhesive applications on the bond strength between composite resin and glass-ionomer cements

OBJECTIVE: This study determined the effects of various surface treatment modalities on the bond strength of composite resins to glass-ionomer cements. MATERIAL AND METHODS: Conventional (Ketac(TM) Molar Quick Applicap(TM)) or resin-modified (Photac(TM) Fil Quick Aplicap(TM)) glass-ionomer cements were prepared. Two-step etch-rinse & bond adhesive (Adper(TM) Single Bond 2) or single-step self-etching adhesive (Adper(TM) Prompt(TM) L-Pop(TM)) was applied to the set cements. In the etch-rinse & bond group, the sample surfaces were pre-treated as follows: (1) no etching, (2) 15 s of etching with 35% phosphoric acid, (3) 30 s of etching, and (4) 60 s of etching. Following the placement of the composite resin (Filtek(TM) Z250), the bond strength was measured in a universal testing machine and the data obtained were analyzed with the two-way analysis of variance (ANOVA) followed by the Tukey's HSD post hoc analysis (p=0.05). Then, the fractured surfaces were examined by scanning electron microscopy. RESULTS: The bond strength of the composite resin to the conventional glass-ionomer cement was significantly lower than that to the resin-modified glass-ionomer cement (p<0.001). No significant differences were determined between the self-etching and etch-rinse & bond adhesives at any etching time (p>0.05). However, a greater bond strength was obtained with 30 s of phosphoric acid application. CONCLUSIONS: The resin-modified glass-ionomer cement improved the bond strength of the composite resin to the glass-ionomer cement. Both etch-rinse & bond and self-etching adhesives may be used effectively in the lamination of glass-ionomer cements. However, an etching time of at least 30 s appears to be optimal.