Association between tumor necrosis factor-α promoter −308 A/G, −238 A/G, interleukin-6 −174 G/C and −572 G/C polymorphisms and periodontal disease: a meta-analysis

The aim of this study was to determine whether tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) promoter polymorphisms confer susceptibility to periodontitis in ethnically different populations. A literature search was performed using PubMed and Embase and a meta-analysis of the identified studies was conducted to explore the associations between TNF-α −308 A/G, −238 A/G, IL-6 promoter −174 G/C and −572 G/C polymorphisms and periodontitis. Seventeen comparison studies for the TNF-α −308 A/G polymorphism and three studies for the TNF-α −238 A/G polymorphism were included in the meta-analysis. And 16 separate studies for the IL-6 −174 G/C polymorphism and 10 studies for the IL-6 −572 G/C polymorphism were considered in our meta-analysis. Analysis after stratification by ethnicity indicated that the TNF-α −308 A allele was associated with periodontitis in Brazilian, Asian, and Turkish populations (OR = 0.637, 95 % CI = 0.447–0.907, p = 0.013; OR = 0.403, 95 % CI = 0.204–0.707, p = 0.009; OR = 1.818, 95;  % CI = 1.036–3.189, p = 0.037). The meta-analysis showed no association between the TNF-α −238 A/G polymorphism and periodontitis. The meta-analysis indicated an association of the IL-6 −174 G/C polymorphisms with periodontitis in Brazilian populations (OR for GG + GC = 2.394, 95 % CI = 1.081–5.302, p = 0.031). Stratification by ethnicity and disease type indicated an association between the IL-6 −572 G allele and chronic periodontitis (OR = 1.585, 95 % CI = 1.030–2.439, p = 0.036), and periodontitis in Europeans (OR = 2.118, 95 % CI = 1.254–3.577, p = 0.005). This meta-analysis demonstrates that the TNF-α −308 A/G polymorphism confers susceptibility to periodontitis in Brazilian, Asian and Turkish populations. The IL-6 −174 G/C polymorphism may confer susceptibility to periodontitis in Brazilians, and the IL-6 −572 G/C polymorphism may be associated with susceptibility to periodontitis in Europeans, and chronic periodontitis.