Comparison of shear bond strength of resin-modified glass ionomer to mineral trioxide aggregate with different surface pretreatment techniques

Objective: The aim of this study was to evaluate the effects of different cavity disinfection methods on the bond strength of mineral trioxide aggregate (MTA) and glass ionomer cement (GIC) at 3 intervals after placement of MTA. Method: In current study, 180 cylindrical acrylic blocks, each of which had a hole (5 mm in diameter and 2 mm in height) in the middle were used. The samples were divided into three main groups on the basis of the intervals after placement of MTA. Main groups 1, 2 and 3 had intervals of 15 minutes, 24 hours and 72 hours respectively. All 3 groups were divided into 3 subgroups on the basis of the cavity disifection methods. Group A; chlorhexidine gluconate (CHX) (2mL/m, 2%), Group B; ozone (output power was 10), Group C; diode laser (810 nm, 1.5W, with 15-second cycle) and Group D was the control group. After all cavity disinfection methods were applied to all groups, GIC was applied with the aid of a 4 mm height 3 mm diameter flexible plastic tube on the MTA and cured immediately. After curing process, plastic tubes were removed. A universal testing machine was used for shear bond strength test. Shear bond strength in MPa was calculated by dividing the peak load at failure with the specimen surface area. Statistical analysis was performed. Results: Cavity disinfection with ozone and diode laser showed no significant differences according to the control group (P>0.05). CHX group showed significantly lower bond strength than the control group (P<0.05). There was no statistically significant difference between the intervals (15 m, 24 h, 72 h) after placement of MTA. Conclusion: In current study, CHX lowered the bond strength between MTA and GIC when used as a base material while ozone and diode laser had no negative effect. GIC can be successfully applied on MTA after a 15 min interval.