MMP8 and periodontitis: Among the 23 types of MMPs already identified, the upregulation of MMP-8 and -9 has been related to periodontitis and peri-implantitis (Franco et al., 2017; Checchi et al., 2020) and it is associated with disease progression and bone loss (Arakawa et al., 2012; Al-Majid et al., 2018).