Effects of different irrigating solutions and disinfection methods on push-out bond strengths of fiber posts

The aim of this study was to evaluate the effects of various irrigating solutions and photoactivated disinfection (PAD) on the push-out bond strengths of fiber posts to root dentin.

Thirty-two human teeth were divided into eight groups, as follows: (1) irrigation with physiologic saline (control), (2) NaOCl irrigation, (3) chlorhexidine (CHX) irrigation, (4) ethanol (EtOH) irrigation, (5) NaOCl followed by 17% EDTA irrigation, (6) NaOCl-EDTA supplemented with CHX irrigation, (7) NaOCl-EDTA supplemented with EtOH irrigation and (8) NaOCl-EDTA irrigation supplemented with PAD. After the posts were cemented, the roots were transversally sectioned to obtain four slices (1 mm thick) (n = 16). Push-out tests were conducted by applying a load at 0.5 mm/min, types of fracture failures were recorded and data were analyzed with one-way ANOVA and Tukey post-hoc tests (p = 0.05).

Push-out bond strength was significantly affected by the type of irrigating solution and the disinfection protocol (p < 0.05). The bond strength of the EtOH, NaOCl and NaOCl-EDTA-CHX irrigated groups was significantly higher than that of the other groups. The highest bond strength was observed in the EtOH irrigated group and the lowest was the NaOCl-EDTA irrigated group.

Irrigation with NaOCl and EDTA combined caused lower bond strength than observed in the control group. However, supplementing this combination with CHX improved the post-dentin bond strengths; supplementing with PAD did not.