Clinical and microbiological effects of multiple applications of antibacterial photodynamic therapy in periodontal maintenance patients. A randomized controlled clinical study

Background: At present, very limited data are available on the clinical and microbiological outcomes obtained following repeated application of aPDT following one single mechanical debridement. Objective: To evaluate clinically and microbiologically the outcomes following one single session of subgingival mechanical debridement (scaling and root planing; e.g. SRP) followed by lx immediate application of aPDT and 2 x subsequent use of aPDT without SRP. Materials and methods: Forty patients diagnosed with generalized chronic periodontitis that were enrolled in periodontal maintenance (supportive periodontal therapy) program, were randomly assigned to one of the two treatments: 1. SRP by means of ultrasonic and hand instruments followed by one single session of SRP followed by 1x immediate application of aPDT and 2 x subsequent applications of aPDT without SRP (test) or 2. SRP alone (control). The following clinical parameters were recorded at baseline, at 3 and 6 months: Full-Mouth Plaque Scores (FMPS), Full-Mouth Bleeding Scores (BOP), Probing Pocket Depth (PPD), Clinical Attachment Level (CAL) and Gingival Recession (RC). Additionally, microbiological samples were evaluated at baseline and six months after treatment. The primary outcome variable was BOP. Results: Both treatments improved statistically significantly (p < 0.05) the FMPS, PPD and CAL values, while no statistically significant changes occurred in terms of RC. In the test group, BOP decreased statistically significantly (p < 0.05) after 3 and 6 months, while in the control group the respective values decreased statistically significantly only at 3 months. Both treatments reduced statistically significantly the total bacteria counts (TBC) after 6 months (p < 0.05). At 6 months, the use of SRP and aPDT resulted in a statistically significant decrease in the number of all tested bacteria except A. actinomycetemcomitans while the use of SRP alone resulted only in a statistically significant decrease in the numbers of P. gingivalis, T. denticola and T. forsythia. Conclusions: In periodontal patients enrolled in a maintenance program one single session of SRP followed by 3x application of aPDT, enhanced the clinical and microbiological outcomes compared to SRP alone.