The effect of retreatment on the push out bond strength of MTA Fillapex and AHplus sealers

Abstract

Endodontic retreatment procedures might affect the capacity of refilling materials to adhere to the canal wall dentin. The aim of the present study was to evaluate the effect of endodontic retreatment on the bond strength of one MTA-based sealer (MTA Fillapex) and an epoxy resin-based sealer (AH-plus). Materials and methods: The root canals of 80 human mandibular premolars were prepared with Protaper rotary files up to #F3 master apical file. Then the roots were randomly divided into two groups. The root canals in group A (n=40) and group B (n=40) were obturated with gutta-percha and MTA Fillapex and AH-plus sealers, respectively, using lateral compaction technique. The teeth in both groups were randomly divided into two subgroups. In subgroups A1 and B1 no endodontic retreatment was carried out; however, in subgroups A2 and B2 retreatment was carried out with Protaper Universal retreatment instruments (D1, D2 and D3) using chloroform as a solvent. After completion of retreatment procedures, the root canals in A2 and B2 subgroups were refilled with gutta-percha and MTA Fillapex and AH-plus sealers, respectively, using lateral compaction technique. After two weeks of incubation, four 2-mm slices were prepared from each tooth at a distance of 2 mm from the coronal surface and underwent a push-out test. Results: The results showed significant differences in mean bond strength values between the two sealers, irrespective of the procedure carried out (P<0.001), with higher bond strength with AH-plus sealer compared to MTA Fllapex sealer. Comparison of the mean bond strength vales in the study subgroups did not reveal significant differences, irrespective of the sealer type (P=0.3); in addition, the interaction between the type of the treatment and the type of the sealer was not statistically significant (P=0.5). Conclusion: AH-plus sealer exhibited a higher bond strength compared to MTA Fillapex and endodontic retreatment with rotary files and use of chloroform as a solvent did not exert a significant effect on the bond strength of sealers under study