LAUSR

BACKGROUND This study aimed to assess the effect of ultrasonic activation of photosensitizer on the efficacy of Antimicrobial Photodynamic Therapy (aPDT) against Enterococcus faecalis and penetration depth of photosensitizer. MATERIALS AND METHODS In this ex vivo study, mature microbial biofilm of E. faecalis was formed in the root canals of 58 single-rooted single-canal mandibular incisors following their decoronation. The roots were longitudinally sectioned by a diamond disc and split into halves by a chisel. The E. faecalis biofilm was quantified and the penetration depth of photosensitizer was determined by the microbial viability assay and stereomicroscopic analysis in the following three study groups: (1) Ultrasonically activated 5.25% sodium hypochlorite (NaOCl) for 20 seconds, (2) aPDT using methylene blue (MB) plus 660 nm diode laser with 150 mW power for 1 minute, and (3) ultrasonically activated MB for 20 seconds followed by laser irradiation as in group 2. Independent sample t-test and one-way ANOVA were used to compare the dye penetration depth and microbial load, respectively in the apical and coronal regions among the groups. RESULTS The penetration depth of photosensitizer in group 3 was significantly greater than that in group 2 (P < 0.05). The E. faecalis count in all three experimental groups was significantly lower than that in the control group (P < 0.05). Groups 1 and 3 were significantly superior to group 2 in terms of reduction in microbial count but the difference between groups 1 and 3 was not significant (P > 0.05). CONCLUSION Ultrasonic activation of photosensitizer in aPDT increases the penetration depth of photosensitizer into the dentinal tubules and enhances its antibacterial activity. HIGHLIGHT Ultrasonic activation of photosensitizer in aPDT enhances its penetration depth into dentinal tubules. Ultrasonic increase antibacterial efficacy of aPDT. There was no significant difference between antibacterial effects of aPDT + ultrasonic and ultrasonic activated NaOCl.