Abstract: PURPOSE: To compare the biomechanical effects and tissue reparability of photodynamic and laser in the adjuvant treatment of peri-implantitis. METHODS: A total of 112 patients with peri-implantitis who were diagnosed and treated from March 2023 to April 2024 were randomly divided into the control group and the experimental group, with 56 cases in each group. On the basis of conventional symptomatic treatment, the control group received photodynamic therapy and the experimental group received laser therapy. The biomechanical effects [implant mobility(IM), peri-implant bone density(PBD), mesial and distal marginal bone resorption of the implant], tissue reparability[sulcus bleeding index (SBI), plaque index (PLI) and probing depth (PD)], inflammatory factors [interleukin-6 (IL-6), tumor necrosis factor (TNF-α), and matrix metalloproteinases-8(MMP-8)] and the proportion of Porphyromonas gingivalis(P.g) in the total bacterial count were compared before and 1, 2, and 3 months after treatment between the two groups. SPSS 26.0 software package was used for statistical analysis of the data. RESULTS: After 1-3 months of treatment, both groups showed significant decrease in IM, mesial and distal marginal bone resorption of the implant, SBI, PLI, PD, IL-6, TNF-α, MMP8, and the proportion of P.g to total bacteria (P<0.05), and significant increase in PBD (P<0.05). Compared with the control group, the experimental group showed significant improvements in IM, PBD, mesial and distal marginal bone resorption of the implant, IL-6, TNF-α and MMP8 (P<0.05). Compared with the experimental group, the control group showed significant improvements in SBI, PLI, PD and the proportion of P.g to total bacteria (P<0.05). CONCLUSIONS: Both photodynamic and laser therapy can be used in the adjuvant treatment of peri-implantitis. Photodynamic therapy has advantages in tissue repair and reducing the proportion of P.g to total bacteria, while laser therapy has advantages in biomechanical effects and reducing inflammatory factors.

Key words: Photodynamic therapy, Laser therapy, Peri-implantitis, Biomechanical effects, Tissue repair