TNF and periodontitis: Furthermore, only a small number of researchers have found evidence to support the link between TNF-α and periodontitis,10,24 and even fewer have found evidence to support the association.30,34 Therefore, using the new 2017 classification system for periodontal disease, the purpose of this study was to compare the levels of TNF-α and caspase-1 in the saliva of periodontitis patients vs periodontally healthy subjects .