Early failure of dental implants and TNF-alpha (G-308A) gene polymorphism

Tumor necrosis factor-alpha (TNF-alpha) is a potent inflammatory mediator with bone resorption activity. Polymorphisms in the promoter region of the human TNF-alpha gene have been shown to affect the levels of this cytokine and have been associated with a variety of diseases. The aim of this study was to investigate the possible relationship between early implant failure and a single nucleotide polymorphism (SNP) in the -308 promoter region of the TNF-alpha gene. A sample of 66 nonsmokers was divided into 2 groups: a test group comprising 28 patients (mean age, 52.7 years) with one or more early failed implants and a control group consisting of 38 individuals (mean age, 43.2 years) with one or more healthy implants. Genomic DNA from buccal mucosa was amplified by the polymerase chain reaction (PCR), analyzed by restriction fragment length polymorphism (RFLP), and submitted to polyacrylamide gel electrophoresis to distinguish allele G and allele A of the TNF-alpha (-308) gene polymorphism. Differences in the allele and genotype frequencies between control and test groups were assessed by chi-squared test (P <0.05). No significant difference was observed in the allele (P = 0.4635) and genotype (P = 0.4445) distribution of the polymorphism when control and failure groups were compared. The results indicate that the TNF-alpha (G-308A) gene polymorphism is not associated with early implant failure, suggesting that its presence alone does not constitute a genetic risk factor for implant loss in the Brazilian population.