Association between TLR4 polymorphism and periodontitis susceptibility: a meta-analysis

TLR4 has been implicated in periodontal disease, but the association between the TLR4 Asp299Gly and Thr399Ile polymorphisms and the risk of periodontal disease remains unclear. Therefore, the aim of this study was to investigate the association between the TLR4 Asp299Gly and Thr399Ile polymorphism and periodontal disease. A search of electronic databases identified previous studies evaluating the association of the polymorphisms of TLR4 and periodontitis risk. The association was evaluated by odds ratio (OR) and its 95% confidence interval (CI). The results showed that TLR4 Asp299Gly and Thr399Ile were not associated with a significant risk of periodontitis (OR = 0.96, 95% CI = 0.80-1.16 for G versus A; OR = 1.39, 95% CI = 0.82-2.36 for AG/GG versus AA; OR = 1.05, 95% CI = 0.52-2.15 for T versus C; OR = 0.76, 95% CI = 0.55-1.04 for CT/TT versus CC). In the stratified analyses, there was no significantly increased risk for the studies of chronic periodontitis and aggressive periodontitis. Our meta-analysis revealed that the two common TLR4 polymorphisms, Asp299Gly and Thr399Ile, have no association with the likelihood of periodontitis. In a subgroup analysis by ethnicity and periodontitis type, the results also did not show any association. However, there was a significant increased risk for periodontitis in recessive models of Asp299Gly. The effect of genetic networks and their mutual interactions in the TLR4 signaling pathway on periodontitis susceptibility needs further study.