Influence of final irrigation protocols and type of resin cement on bond strength of glass fiber posts in root dentin previously treated with photodynamic therapy.

INTRODUCTION: This study aimed to evaluate the influence of final irrigation protocols and type of resin cement on the bond strength of glass fiber posts (GFPs) in root dentin previously treated with photodynamic therapy (PDT). METHODS: One hundred root canals were prepared up to #4 Gates Glidden drill to receive the GFPs. All samples were subjected to PDT, and randomly divided into five groups (n = 20) according to final irrigation protocol: distilled water + ultrasonic activation [US]; 17% EDTA; QMix; 17% EDTA + US; and QMix + US. Each group was randomly divided into 2 subgroups (n = 10) according to the type of resin cement used for cementation of GFPs: Rely-X ARC dual-resin; or Rely-X U200 (#M, St Paul, MN, USA) self-adhesive resin cement. Bond strength was evaluated using the push-out test. Failure patterns were observed under an optical microscope. Bond strengths were compared using two-way ANOVA, followed by the Tukey post-hoc test; failure modes were compared using the chi-squared test (α = 5%). RESULTS: The use of US over final irrigants improved the bond strength of GFPs, regardless of resin cement used (p < 0.05). The type of resin cement did not influence the bond strength of GFPs (p < 0.05). There was a higher predominance of cohesive failure in all groups, regardless of resin cement tested (p < 0.05). CONCLUSIONS: The use of US on final irrigation improved the bond strength of GFPs, while the type of resin cement (dual or self-adhesive) did not influence the bond strength of GFPs in root dentin previously treated with PDT.

Influence of ultrasonic activation using different final irrigants on antimicrobial activity, smear layer removal and bond strength of filling material.

The aim of this study was to evaluate the influence of ultrasonic activation (US) over final irrigants on antimicrobial activity, smear layer removal and bond strength. The root canals of 180 extracted human teeth were distributed into three experimental tests (n = 60). In each test, the samples were subdivided into six groups (n = 10) according to final irrigation protocols: G1:distilled water (DW); G2:DW + US; G3:17% EDTA; G4:QMix; G5:17% EDTA + US; and G6:QMix + US. The antimicrobial activity was evaluated by counting of colony-forming units (CFUs), the smear layer removal by scanning electron microscopy and the bond strength by push-out test. Statistical analysis was performed for each evaluation (α = 5%). Groups 4 and 6 provided higher bacterial reduction, groups 5 and 6 provided higher smear layer removal, groups 3, 4, 5 and 6 provided the higher bond strength (P < 0.05). US activation did not improve the antimicrobial activity and the bond strength, whereas it improved the smear layer removal.