Tehran University of Medical Sciences Iranian Journal of Allergy, Asthma and Immunology 1735-1502 0 0 2026 10 09 1 12 Weijun Zhu Department of Stomatology, The First People's Hospital of Yuhang District, Hangzhou, China Feifei Hong Department of Periodontology I, Stomatological Hospital of Xiamen Medical College, Xiamen Key Laboratory of Stomatological Disease Diagnosis and Treatment, Xiamen, China Lie Wang Department of Stomatology, Wuhan Third Hospital, Wuhan, China 2026 04 03 2026 06 11 To evaluate the effects of non-surgical treatment on inflammatory factor levels in patients with peri-implantitis (PI). PubMed, Web of Science, ScienceDirect, China National Knowledge Infrastructure, and Wanfang were searched through March 2026 for randomized controlled trials of non-surgical therapy for PI. Outcomes included interleukin 1β (IL-1β), interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), and matrix metalloproteinase 8 (MMP-8). Meta-analysis was performed using RevMan 5.3. Fourteen trials were included. At 3 months, adjunctive non-surgical treatment produced greater reductions than control treatment in gingival crevicular fluid IL-1β (SMD, −0.78; 95% CI, −1.29 to −0.26), IL-6 (SMD, −1.49; 95% CI, −2.07 to −0.91), and TNF-α (SMD, −1.84; 95% CI, −3.05 to −0.63), but not MMP-8 (SMD, 0.08; 95% CI, −1.33 to 1.50). At 6 months, no between-group difference was observed for IL-1β (SMD, −0.18; 95% CI, −0.61 to 0.25). PDT-based regimens reduced IL-1β and TNF-α more than controls at 3 months, whereas laser-based regimens showed no clear advantage. Non-smokers showed greater IL-1β improvement than smokers. Sensitivity analyses supported the IL-1β, IL-6, and TNF-α findings, but the MMP-8 result was unstable. GRADE evidence quality was moderate for IL-1β, IL-6, and TNF-α and low for MMP-8. Non-surgical treatment may reduce gingival crevicular fluid IL-1β, IL-6, and TNF-α levels in the short term. Non-smokers may respond better than smokers, and PDT-based regimens may be more effective than laser therapy; however, benefits were not sustained at 6 months. https://ijaai.tums.ac.ir/index.php/ijaai/article/view/4783 https://ijaai.tums.ac.ir/index.php/ijaai/article/download/4783/2436