TNF and periodontitis: Salivary melatonin is closely related to clinical periodontal parameters; melatonin is inversely correlated with gingival inflammation parameters, which inhibit inflammation-induced alveolar bone loss and the expression of the proinflammatory factors TNF-α and IL-1β in periodontal tissue of periodontitis rats, and periodontal therapy can restore saliva melatonin (Konečná et al., 2021; Park and Tokura, 1999).