Changes in the total bacterial (a) and Porphyromonas gingivalis (b) counts after each treatment. Microbiological analysis was conducted with the invader-PCR technique. The values and error bars represent the means and 95% confidence intervals, respectively. Significant differences detected between Groups 1 and 3 are denoted by *P < 0.05 and **P < 0.01. Group 1, root debridement + H2O2 photolysis; Group 2, root debridement + local drug delivery system; and Group 3, root debridement alone.