Forest plot on 18 studies for the association between the G allele of the IL6 rs1800796 and periodontitis in (A) all studies; (B) subgroup of East Asians; (C) subgroup of Caucasians; (D) subgroup of Chinese. Data were synthesized with fixed effects meta-analysis with odds ratios (ORs) and 95% confidence intervals (CI) being calculated. Pooled effect estimates are indicated by diamonds, with I² and significance of the overall effect being given. When the number of studies was more than four or the I² was more than 50% in case P-value of heterogeneity less than 0.05, OR and P-value were calculated using random effect model