Influence of Smoking on Interleukin-34 Levels in Gingival Crevicular Fluid and Plasma in Periodontal Health and Disease: A Clinico-biochemical Study.

Interleukin-34 (IL-34), an alternative ligand for macrophage colony-stimulating factor receptor, plays an important role in osteoclastogenesis. The aim of this study was to analyze the effect of smoking on IL-34 levels in gingival crevicular fluid (GCF) and plasma in individuals with healthy periodontium and chronic generalized periodontitis (CP). A total of 60 individuals ranging in age from 25 to 55 years were enrolled in the study. The participants were divided into 4 groups: Group A, 30 samples (15 GCF and 15 plasma) obtained from 15 non-smokers with healthy periodontium; Group B, 30 samples (15 GCF and 15 plasma) from 15 smokers with healthy periodontium; Group C, 30 samples (15 GCF and 15 plasma) from 15 non-smokers with CP; and Group D, 30 samples (15 GCF and 15 plasma) from 15 smokers with CP. The Gingival Index and probing depth scores, together with the Clinical Attachment Level, were assessed in each group as clinical periodontal parameters. Levels of IL-34 in GCF and plasma were quantified using enzyme linked immunosorbent assay. The results showed that the mean IL-34 concentrations in GCF and plasma were highest in Group D, followed by Group C, Group B, and Group A, and the difference among them was statistically significant (p<0.05). The relatively elevated IL-34 levels observed here in smokers with CP suggest that this cytokine offers a potential inflammatory marker of periodontal disease in smokers.