Previous reports indicated that periodontal microbial infection enhances MMP‐8 gene and protein expression from HGFs and PDL cells and that the amount of MMP‐8 in the gingival crevicular fluid, gingival tissue, and PDL cells significantly increased in patients with chronic periodontitis (Escalona et al., 2016; Finoti et al., 2017). This evidence concerns the gene MMP8 and chronic periodontitis.