Influence of synthetic and natural photosensitizers activated by photodynamic therapy on extrusion bond strength of fiber post to radicular dentin.

Objective: To assess the effect of different photosensitizers activated by low-level laser therapy on EBS of glass fiber post to radicular dentin.

Methods: This study was conducted at King Saud University from January 2021 to March 202. Fifty maxillary central incisors were sanitized and decoronated. NiTi was used for mechanical instrumentation of the canal. All canals were shaped, cleaned and obturated with gutta-percha. Post space was made using peso reamers. Four Division of groups were made according to photosensitizers used (n=10). Group-1: MBP at 100mg/l, Group-2: Phycocyanin at 100mg/l, Group-3: CP at 500mg/l, and Group-4 toluidine blue photosensitizer (TB). Lasers were used for activation of photosensitizers. In Group-5 samples were irrigated using sodium hypochlorite NaOCl +17% EDTA. Posts were cemented and teeth sectioned into apical, coronal and middle. For EBS all samples were subjected to a universal testing machine. Fracture patterns were analyzed using stereomicroscope. To compare EBS at different segments One-way analysis of variance (ANOVA) and Tukey multiple comparison tests (=0.05) was performed.

Results: The maximum value of EBS was shown in Group-2 radicular canal treated with CP with 17% EDTA at all three levels cervical (8.61±1.32 MPa), middle (6.81±0.73 MPa), and apical (5.51±0.25 MPa). Similarly, the minimum value of EBS was displayed in Group-5 canal irrigated with 2.25% NaOCl +17% EDTA (control) coronal (6.10±1.77 MPa), middle (5.11±0.75MPa), and apical (3.60±0.94 MPa). Intragroup assessment disclosed a decrease in EBS from cervical one-third to apical one-third in all groups.

Conclusion: P, CP, and TB along with EDTA have the potential to be used as canal disinfectant and favors the bonding of GFP to radicular dentin using self-etch adhesive resin.