TNF and periodontitis: Several polymorphisms in the promoter region of TNF-α have been identified, and the 308G/A and 863C/A polymorphisms may contribute to the susceptibility of periodontitis according to a meta-analysis.22 The TNF level was also shown to be elevated in the GCF122 and serum123 of chronic periodontitis patients, while no decrease in TNF was observed after NSPT.