Background: The aim of the present study was to evaluate gingival crevicular fluid (GCF) leptin levels and the influence of long-term and heavy smoking on GCF leptin levels in patients with chronic periodontitis.

Methods: In this study, 143 individuals were divided into three groups: non-smokers (NS), smokers (S), and control (C). Three subgroups of NS and S were grouped as follows: a) probing depth (PD) ≤3 mm; b) PD = 4 to 5 mm; and c) PD >5 mm. For each patient, PD, gingival index (GI), plaque index (PI), gingival bleeding time index (GBTI), and clinical attachment level (CAL) values were recorded. The GCF leptin levels obtained from sampling sites were determined by using enzyme-linked immunosorbent assay kits.

Results: The GCF leptin levels were found significantly lower in the a and b subgroups in the S group than those in the NS group (P <0.05). The inflammatory markers GI and GBTI showed significant correlations with leptin in NS (P <0.05).

Conclusions: Our results suggest that higher leptin GCF levels in healthy sites in periodontitis patients may play a protective role in periodontal disease. Further studies are needed to determine the cellular origin of the leptin in the gingiva and the effect of plasma leptin levels on GCF leptin concentrations.