Evaluation on features of “micro-inflammation” in periodontitis patients after nonsurgical therapy: a preliminary pilot study

BACKGROUND: In periodontitis patients, periodontium inflammatory levels may remain even after systematic treatment, impeding efficacy of stem cell therapy. This study aimed to compare periodontal parameters and gingival crevicular fluid (GCF) and serum inflammatory profiles among healthy individuals, pre- and post-treatment periodontitis patients, and based on the data, describe the post-treatment "micro-inflammation" in periodontium of periodontitis patients. METHODS: Ten healthy individuals (group H) and twenty-three periodontitis patients (group P) were included. Group P participants received full-mouth non-surgical periodontal treatment at baseline, and were followed up 4 and 12 weeks later. The GCF and serum samples were collected and periodontal clinical parameters were recorded. Seven inflammatory markers in the samples were assessed using enzyme-linked immunosorbent assay, including lipopolysaccharides (LPS), tumor necrosis factor-alpha (TNF-α), interleukins (IL)-6, IL-1β, Matrix metalloproteinase-8 (MMP-8), Interferon-gamma (IFN-γ) and IL-17 A. RESULTS: The amounts of TNF-α, IL-1β, IL-6, IL-17 A, MMP-8 and LPS in periodontitis patients' GCF decreased significantly both 4 and 12 weeks after treatment (p < 0.05), while still higher than healthy individuals (p < 0.05); strong positive correlations were shown between these biomarker amounts in GCF and clinical parameters (P < 0.05), such as pocket depth and clinical attachment loss. Amounts of IFN-γ were similar between periodontal patients after treatment and healthy individuals. When measured with concentrations, LPS and TNF-α decreased after treatment (P < 0.05) and remained higher than group H (P < 0.05); IL-1β and MMP-8 in group P did not change significantly after treatment and were similar to those in group H. No biomarker in serum showed meaningful differences. CONCLUSION: Low-grade and sustainable inflammation in the post-treatment periodontium continues, which was termed "micro-inflammation". The amounts of TNF-α, IL-1β, IFN-γ, IL-6, IL-17 A, MMP-8 and LPS in GCF can be used to describe characteristics of microinflammation, serving as reference for stem cell therapy on periodontal regeneration. TRIAL REGISTRATION: This study was registered at Chinese Clinical Trial Registry (ChiCTR; registration number: ChiCTR2400088098, registration date: Aug 12, 2024).