de Morais EF, et al. - This systematic review purposefully determined the scientific literature regarding the expression of matrix metalloproteinase-8 (MMP-8) in gingival crevicular fluid and salivary fluid (SF) in patients with periodontal disease, investigating its validity as a possible biomarker for the diagnosis of periodontal disease. The present study showed significantly higher concentrations of MMP-8 in patients with periodontal disease compared with controls, as well as in patients presenting more advanced stages of periodontal disease. In addition, the findings on higher MMP-8 concentrations in patients with periodontal disease compared with controls suggested the potential adjunctive use of MMP-8 in the diagnosis of periodontal disease.