Abstract: PURPOSE: To explore the clinical effect of subgingival scaling and root planning (SRP) with adjunctive photodynamic therapy (PDT) in the treatment of stage Ⅲ and Ⅳ periodontitis. METHODS: According to 2018 Classification of Periodontitis, patients diagnosed as stage Ⅲ and Ⅳ periodontitis were recruited. One week after supragingival scaling, probing depth (PD), bleeding on probing (BOP) and gingival index (GI) were recorded as the baseline. All patients were divided into 3 groups, SRP group received whole mouth SRP treatment; PDT1 group: PDT at all sites with PD≥5 mm immediately after SRP; PDT2 group received another PDT at the test sites 6 weeks after full mouth SRP+PDT. PD, GI and the positive rates of BOP were compared 3 months and 6 months after treatment. SPSS 22.0 software package was used for data analysis. RESULTS: Thirty patients and 1 289 test sites were included in this trial. There were 10 patients in group SRP, PDT1 and PDT2, and the number of tests sites were 476, 36.9%, 384, 29.8% and 429 33.3%, respectively. The PD, GI and the positive rates of BOP in the three groups were reduced at 3-months and 6-months of follow-up (P<0.05), there was no significant difference between 3-months and 6-months of follow-up. At the site of PD≥5 mm, group PDT1 and PDT2 could significantly reduce GI and the positive rates of BOP at the test sites(P<0.05). When PD≥7 mm, significant PD reduction was observed in group PDT2(P<0.05). CONCLUSIONS: In the treatment of stage Ⅲ and Ⅳ periodontitis, PDT assisted with SRP therapy can achieve better clinical effect than SRP alone.

Key words: Photodynamic therapy, Subgingival scaling and root planning, Advanced periodontitis