Salivary RANKL and OPG in Smokers versus Non-smokers with Periodontitis

Objectives: RANKL and osteoprotegerin (OPG) are believed to be key factors regulating bone metabolism and it is likely that they are involved in regulation of alveolar bone destruction. This study was conducted to compare salivary RANKL and osteoprotegerin (OPG) concentrations in smokers versus non-smokers with chronic periodontitis.

Methods: Fifty-five non-smoker and 56 smoker untreated chronic periodontitis patients were evaluated. Whole saliva samples were obtained before periodontal intervention. Full-mouth clinical periodontal measurements were taken using the Williams periodontal probe. Saliva concentrations of cotinine, sRANKL and OPG were determined by ELISA. Statistical analysis was performed using the Mann-Whitney U test and Bonferroni correction for multiple comparisons. Spearman correlations were utilized to look at the relationship between salivary concentrations of sRANKL, OPG and the clinical parameters.

Results: Smoker patients exhibited significantly higher values of probing depth, clinical attachment level, bleeding on probing (all p<0.05). Salivary OPG concentration was significantly lower (p<0.001) and sRANKL/OPG ratio was higher (p=0.006) in the smokers compared to the non-smokers. OPG concentration correlated positively with probing depth, clinical attachment level, bleeding on probing (all p<0.005) and negatively with pack-year and cotinine level (p<0.05). Salivary cotinine level correlated with the clinical attachment level (p=0.023).

Conclusion: Findings of this study suggest that OPG concentrations in saliva are affected by smoking and the significantly decreased RANKL/OPG ratio in smokers provides further support for the hypothesis that smoking increases the risk for periodontitis.