MMP9 and periodontitis: However, although at present there is a certain amount of preliminary evidence that analyzes serum or salivary levels such as in patients with periodontitis or with CVD, to the authors’ knowledge, there is no targeted evidence that has correlated serum and salivary levels of MMP-9 in patients with periodontitis and CVD in order to better understand the role of this mediator as an early marker of CVD or endothelial risk.