Comparison of the bond strength of resin modified glass ionomer & composite resin to calcium enriched mixture, mineral trioxide aggregate(MTA) and MTA mixed with disodium hydrogen phosphate

Abstract

Bond strength between restorative materials and pulp capping agents plays a prominent role in treatments success. The aim of the present study was to compare the bonding strength of RMGI and composite to the surface of CEM, NAMTA and MTA. Materials and methods: In this study, 90 acrylic cylindrical blocks were prepared. Each block had a cylindrical hole in the center with a diameter of 4 mm and depth of 2 mm, in which the substrate was placed using a carrier according to the manufacturers instructions. Samples were divided to two main groups, and then into three subgroups (15 samples in each subgroup), and were prepared in the following sequence: Group I: Composite ubgroup A: CEM surface Subgroup B: NAMTA surface Subgroup C: MTA surface Group II: RMGI Subgroup A: CEM surface Subgroup B: NAMTA surface Subgroup C: MTA surface. Shear bond strengths were measured using universal testing machine equipped with knife edge blade with a pace of 1 mm per minute and continued until the bond of composite and RMGI with MTA, NAMTA and CEM was broken. Mean shear bond strength and the standard deviations were calculated separately for each subgroup. The obtained data were analyzed with two-way ANOVA and post-hoc Tukey test, and for analyzing the bond strength between subgroups, the one away ANOVA analysis was employed with a significance level of P < 0.05. Results: According to two-way ANOVA analysis, difference of bond strength between the two groups of composite and GI was significant (p < 0.001), and the bond strength of composite was significantly higher than GI. In composite group, the comparison of subgroups with one away ANOVA showed a significant difference of bond strength between substrates. Tukey post-hoc test showed a significant difference of bond strength between MTA and CEM subgroups (P = 0.026) and MTA and NAMTA subgroups (P = 0.019); however, no significant difference was seen between NAMTA and CEM subgroups (p = 0.56). In RMGI group, the difference of shear bond strengths between subgroups was not significant (p = 0.058). Conclusion: Bond shear strength between resin composite and (MTA, CEM, NAMTA) was significantly higher than the bond between RMGI and (MTA, CEM, NAMTA). In resin composite, the bond shear strength with MTA was lower than those of CEM and NAMTA. No significant difference was observed in RMGI subgroups.