Saliva concentrations of RANKL and osteoprotegerin in smoker versus non-smoker chronic periodontitis patients

Objectives: To compare the salivary receptor activator of NF-kappa B ligand (RANKL) and osteoprotegerin (OPG) concentrations in smokers versus non-smokers with chronic periodontitis. Materials and Methods: Whole saliva samples were obtained from 67 untreated chronic periodontitis patients, of whom 34 were smokers, and from 44 maintenance patients, of whom 22 were smokers. Full-mouth clinical periodontal measurements were recorded. Saliva cotinine, sRANKL and OPG concentrations were determined by ELISA. Statistical analysis was performed using the Mann-Whitney U test, Bonferroni's correction for multiple comparisons and Spearman's correlations. Results: Untreated smokers exhibited significantly higher values of clinical periodontal recordings than untreated non-smokers (all p < 0.05). Salivary cotinine level correlated with clinical attachment level (p=0.023). Smoker versus non-smoker maintenance groups showed no significant differences in clinical parameters. There were significant differences in sRANKL and OPG concentrations between untreated and maintenance groups (all p < 0.01). Salivary OPG concentration was significantly lower (all p < 0.01) and the sRANKL/OPG ratio was higher (all p < 0.01) in smokers than in non-smokers. OPG concentration correlated positively with probing depth, clinical attachment level and bleeding on probing (all p < 0.005) and negatively with pack-year, and cotinine level (p < 0.05). Conclusion: Salivary RANKL and OPG concentrations are suggested to be affected by smoking as not only the untreated but also the treated smokers exhibited higher RANKL and lower OPG concentrations than non-smokers.