TLR9 and tongue squamous cell carcinoma: T. denticola is also known to be associated with the development and progression of oral cancer.108 In vitro studies have found that Td-CTLP, a virulence factor of T. denticola, is detected in tongue squamous cell carcinoma and may regulate tumor-associated immunomodulatory proteins, such as upregulation of MMP-8 and MMP-9, promote the occurrence and development of tumors.109 Listyarifah et al. also found that Td-CTLP is significantly present in early tongue squamous cell carcinoma (MTSCC), and its expression is related to tumor invasion depth, tumor diameter, TLR-7, TLR-9 expression.