MMP9 and periodontitis: aMMP-8 levels indicating active collagenolysis and periodontal degeneration had the best precision when adjunct with the questionnaire compared with total MMP-8, active MMP-9, total MMP-9 and calprotectin and the plain questionnaire to improve the identification of the undiagnosed periodontitis cases that need to be referred to a dentist (Figure 1 and Table 1).