Impact of tooth-related factors on photodynamic therapy effectiveness during active periodontal therapy: A 6-months split-mouth randomized clinical trial

Background: The persistence of periodontal pockets > 5 mm after periodontal treatments increases the risk of periodontitis recurrence and the need of periodontal surgery. This study evaluated the impact of tooth-related factors on the effectiveness of adjunctive photodynamic treatment (PDT) in the reduction of pockets > 5 mm during active periodontal treatment. Methods: Thirty-six patients suffering from severe chronic periodontitis were evaluated in a 6-months splitmouth randomized clinical trial. Each quadrant was assigned to test (scaling and root planing (SRP) + PDT) or control (SRP alone) group. PDT was conducted using the toluidine blue O and a light-emitting diode (LED) with a red spectrum. PDT applications were performed immediately after SRP, 7 days later and at 3 months. Plaque index (PI), bleeding on probing (BOP), periodontal pocket depth (PPD), and clinical attachment level (CAL) were recorded at baseline, 3 and 6 months. Results: Multilevel analysis showed a significant reduction of pockets > 5 mm in test group in comparison with control group at 3 (OR = 0.69) and 6 months (OR = 0.77). This effect was mainly observed at 6 months in initially deep sites (PPD > 6 mm) with BOP (OR = 0.57). At sites exhibiting PI > 1 no PDT effect was observed. A more moderate PDT effect was observed on mean PPD and BOP reductions at 3 months only. Conclusions: Repeated applications of PDT significantly improved SRP outcomes, reducing by more than 40% residual pockets > 5 mm in initially deep and bleeding on probing periodontal sites. PDT effect was negatively influenced by dental plaque accumulation.