Impact of subgingival periodontal treatment on systemic markers of inflammation in patients with metabolic syndrome: a systematic review of randomized clinical trials

Introduction: This study synthesizes evidence on the impact of subgingival periodontal treatment combined with antibiotics on reducing systemic inflammation markers—C-reactive protein (CRP), interleukins, and tumor necrosis factor-alpha (TNF-α)—in patients with metabolic syndrome (MS) and periodontal disease (PD), compared to supragingival periodontal treatment with placebo. Methods: Randomized clinical trials (RCTs) published in English, Spanish, or Portuguese that addressed the research question were included. A search was conducted in eight databases (PubMed, EMBASE, CINAHL, LILACS, Scopus, WoS Core Collection, Dentistry & Oral Science Source, and Cochrane Central) on June 20, 2023. Risk of bias was assessed using the Cochrane RoB 2 tool, and evidence certainty was evaluated following GRADE guidelines. A qualitative synthesis of the evidence was performed. Results: Two RCTs with 228 participants (ages 35–65) were included. Montero et al. reported significant reductions in CRP levels favoring the treatment group at 3 months (2.7 mg/L ± SE: 0.4 vs. 3.9 mg/L ± SE: 0.6; p = 0.001) and 6 months (2.9 mg/L ± SE: 0.4 vs. 4.0 mg/L ± SE: 0.8; p = 0.004). Lopez et al., however, found no significant differences throughout follow-up. Only Montero et al. reported on interleukin 1β and TNF-α, observing significant reductions at 3 months for interleukin 1β (0.9 pg/dl ± SE: 0.1 vs. 2.3 pg/dl ± SE: 0.5; p = 0.046) and TNF-α (6.4 pg/dl ± SE: 0.8 vs. 10.0 pg/dl ± SE: 2.3; p = 0.037). Discussion: The evidence is limited by the small number of comparative RCTs. One RCT with low risk of bias demonstrated significant reductions in CRP, interleukins, and TNF-α levels at 3 months and CRP at 6 months. The other, with unclear risk of bias, showed no differences in CRP up to 12 months. Findings suggest that subgingival periodontal treatment with antibiotics reduces systemic inflammation for up to 6 months in patients with MS and PD. However, larger RCTs with standardized methods and longer follow-up are needed to confirm these results. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022366056, PROSPERO (CRD42022366056).