Does cleaning of post space before cementation of fiber reinforced post affect the push-out bond strength to resin cement?

BACKGROUND: Fiber-reinforced posts (FRPs) are preferred for the rehabilitation of endodontically treated teeth. Achieving adequate bond strength between resin cement and root dentin requires effective removal of the smear layer and debris from the post space before cementation. The aim of this study is to evaluate the effect of various post space cleaning methods prior to cementation of fiber-reinforced posts on the push-out bond strength (PBS). METHODS: Ninety-one human premolars underwent root canal treatment, post space preparation and were assigned to seven groups, each using a different cleaning method. These included normal saline (control), sodium hypochlorite, chlorhexidine, EDTA, air abrasion, Katana™ Cleaner, and phosphoric acid. Tapered fiber-reinforced posts were cemented using self-adhesive resin cement. Two middle root slices from each tooth were obtained (26 specimens/group). Then, all specimens were subjected to thermocycling followed by push-out testing. Failure modes were evaluated under a stereomicroscope. Statistical analysis for PBS was performed using Kruskal-Wallis test and Chi-square test was used to analyze failure modes. RESULTS: The mean PBS ± Standard deviation of all groups, ranked from highest to lowest were; Phosphoric Acid 26.61 ± 7.22 MPa, Chlorohexidine 21.33 ± 5.54 MPa, Sodium Hypochlorite 17.77 ± 4.37 MPa, EDTA 16.76 ± 4.54 MPa, air-born particle abrasion 15.72 ± 4.61 MPa, Katana™ Cleaner 15.48 ± 4.06 MPa, and Control 12.73 ± 3.53 MPa. The control group exhibited the lowest PBS, and only phosphoric acid, Chlorohexidine and Sodium Hypochlorite demonstrated significantly higher PBS than control group. A higher frequency of favorable failure mode (Failure Mode 1) was seen in groups treated with phosphoric acid (80%), chlorhexidine (90%), and EDTA (80%), all of which demonstrated higher push-out bond strengths. CONCLUSIONS: Post space cleaning significantly affects PBS. Failure to properly clean the post space before cementation negatively affects the post retention. Cleaning with phosphoric acid demonstrated the highest push-out bond strength, more than double that of control group, followed by chlorhexidine and sodium hypochlorite.