Interestingly, we found that subjects with higher SHBG levels were more likely to develop periodontitis in males younger than 50 years old (tertile2 vs tertile1: OR=1.48, 95% CI=0.99-2.20, p = 0.056; tertile3 vs tertile1: OR=1.84, 95% CI=1.11-3.07, p = 0.019; P for trend = 0.014), while this phenomenon was not present in males older than 50 years. This evidence concerns the gene SHBG and periodontitis.