Effect of Diode Laser irradiation on the Bond Strength of Fiber Posts after Endodontic Retreatment Using Different Sealers.

Purpose: To investigate the effect of diode laser activated irrigation on bond strength between fiber post and radicular dentin after endodontic retreatment using two different sealers. Materials and Methods: Seventy-two extracted human maxillary central incisors were collected, decoronated, endodontically prepared then divided to three groups (n=24) according to sealer type: GP group: gutta-percha without sealer (control group); AD group: AD sealer; and BC group: Bioceramic sealer. Specimens were endodontically retreated after 30 days using the same sealers. 10 mm deep post spaces were prepared in each specimen. Each group was further sub-divided into three subgroups (n=8) according to post space treatment: irrigated with saline (Control), (EDTA) and (laser and EDTA). One tooth from each group was selected for SEM analysis. Posts were cemented, push out tests were performed. Failure modes were analyzed using a digital microscope. Results: With all dentin pretreatment protocols, AD group recorded the highest bond strength mean value followed by GP and BC group respectively, with significant difference (P<0.05) as demonstrated by two-way ANOVA. However, (Laser+EDTA) recorded the highest bond strength followed by (EDTA) and (saline) respectively, with significant difference as demonstrated by three-way ANOVA (P<0.05). There was no-significant difference among root regions (P>0.05). Predominant failure mode was the mixed type as detected by Chi square test. SEM revealed absence of smear layer and opened dentinal tubules after (laser and EDTA) treatment. Conclusions: laser activated irrigation of root dentin significantly improved the bond strength of fiber post after endodontic retreatment with both sealers.