Metallothionein levels in gingival crevicular fluid, saliva and serum of smokers and non-smokers with chronic periodontitis

Background Metallothionein (MT), a cysteine rich protein is involved as a radical scavenger in several pathological conditions associated with oxidative stress; however, its role in periodontal disease still remains elusive. The aim of this cross-sectional study is to determine the serum, saliva and gingival crevicular fluid (GCF) levels of MT in smokers (S) and non-smokers (NS) with chronic periodontitis (CP), and compare them with those of periodontally healthy (PH) individuals. Methods A total of 85 participants were enrolled: 45 patients with CP (23 S [CP+S] and 22 NS [CP+NS]) and 40 PH individuals (20 S [PH+S] and 20 NS [PH+NS]). In all the study participants, clinical periodontal parameters (plaque index, gingival index, sulcus bleeding index, probing depth, and clinical attachment level) were recorded and samples of serum, saliva and GCF were collected. Enzyme-linked immunosorbent assay was used to determine the levels of MT in the samples. Results All periodontal clinical parameters were significantly higher in the CP groups as compared to PH groups (P < 0.05). MT levels in CP+S group were significantly raised in comparison to other three groups. There was no statistically significant difference in MT levels among CP+NS and PH+S groups (P > 0.05); however, relatively higher levels were observed in GCF and saliva in CP+NS group. When all the study groups were observed together, MT levels were positively correlated with clinical parameters. Conclusions Results of present study suggest that smoking and CP can induce the synthesis of MT owing to increased oxidative stress and heavy metals intoxication. Further longitudinal studies with large sample size and an interventional arm are needed to substantiate the role of MT as a potential biomarker in periodontitis.