MMP8 and periodontitis: Noteworthy, collagenolytic and catalytically competent aMMP-8, but not non-collagenolytic and catalytically non-competent total latent pro-MMP-8, is a precise biomarker to detect, monitor, reflect, and indicate progressive collagenolytic periodontitis in its clinically active tissue-destructive phases [12,23,25,32,38,39,40,51,53].