Effect of Chlorhexidine and Benzalkonium Chloride on the Long‑term Push‑out Bond Strength of Fiber Posts

Abstract

Background and Aim: Fiber posts are widely used in endodontically treated teeth with extensive loss of coronal structure. The purpose  of this study was to investigate immediate and the long‑term effects of chlorhexidine (CHX) and benzalkonium chloride (BAC) application,  on the push‑out bond strength of fiber posts.

Material and Methods: Sixty mandibular premolars were decoronated, and  root canal treatment was performed. After post space preparation, the specimens were divided into three groups according to the post  space-surface pretreatment (n = 20); no surface treatment (control group—Group 1), 2% CHX application (Group 2), and 1% BAC  application (Group 3). A self-curing adhesive cement and an etch and rinse adhesive were used for the cementation of posts. Three  sections (one cervical, one middle, and one apical) of 1 mm thickness were prepared from each specimen. A push-out test was performed immediately on the half of the specimen sections (n = 10). The other half of the specimen sections were subjected to 20.000 thermal  cycles before applying the push-out test (n = 10). The failure mode of each specimen was observed under a stereomicroscope at ×40  magnification.

Results: The data were analyzed by one‑way analysis of variance (ANOVA), Tukey Honestly significant difference (HSD),  and Tamhane tests (P = 0.05). The cervical thirds displayed the highest, and the apical thirds showed the lowest values in all groups (P <  0.05), except the control-aged group (P = 0.554). The aged control groups’ values were found to be significantly lower than the aged CHX  and BAC groups (P < 0.001). Aging significantly reduced the bond strength values of specimens in control groups (P < 0.001). However,  aging did not significantly affect the push‑out bond strength values of CHX and BAC groups (P > 0.050). The failure types were adhesive  between the post and cement (type 1) in all groups, except control-aged group (type 2).

Conclusion: The application of 2% chlorhexidine or 1% BAC may be an essential step that can be taken to preserve the bond strength of fiber posts.