Evaluation of the antimicrobial efficacy of different photosensitizers used in post space disinfection and their effects on push-out bond strength

This study aims to evaluate the antimicrobial efficacy of various photosensitizers (PSs) used in post space disinfection and their effects on the push-out bond strength (PBS) of glass fiber posts (GFPs) to radicular dentin. 60 human mandibular premolar teeth were decoronated, and the root canals were prepared using a standardized protocol. All specimens were sterilized. Sterilization was confirmed in 6 randomly selected specimens (negative control). 54 specimens were obturated. Post space was prepared in the roots and contaminated with Enterococcus faecalis (E. faecalis). Bacterial growth was confirmed in 6 randomly selected specimens (positive control). The specimens were randomly assigned to four groups (n = 12) based on the tested irrigation protocols: phthalocyanine (Pc), toluidine blue (TB), 2.5% NaOCl, and control (distilled water). Antibacterial efficacy was assessed using colony-forming unit (CFU) analysis. GFPs were cemented using self-adhesive resin cement. Sections of 2 mm thickness were obtained from the coronal, middle, and apical regions of the GFP area, and PBS was tested using a universal testing machine. Failure modes were examined under a stereomicroscope (40×). The data were statistically analyzed. None of the tested disinfection protocols completely eliminated E. faecalis. The percentage of bacterial reduction was significantly higher in the NaOCl, TB, and Pc groups compared to the control group (P < 0.05). In terms of PBS values, no significant differences were found among different root levels in the TB and Pc groups (P > 0.05). However, in the NaOCl group, PBS values in the middle section were significantly higher than those in the apical and coronal sections (P < 0.05). The most frequently observed failure mode was adhesive. Pc and TB demonstrated antimicrobial efficacy comparable to NaOCl and did not adversely affect the PBS of GFPs to radicular dentin. These findings suggest that antimicrobial photodynamic therapy (aPDT) using Pc and TB may be considered a potential alternative for post space disinfection.