To investigate the molecular forms of salivary matrix metalloproteinase (MMP)‐8 in relation to periodontitis.

Molecular forms, degree of activation and fragmentation of neutrophilic and mesenchymal‐type MMP‐8 isoforms were analysed from salivary samples of 81 subjects with generalized periodontitis, 63 subjects with localized periodontitis and 79 subjects without pocket teeth, by using western‐immunoblots with computer quantitation. In addition, human recombinant proMMP‐8 was in vitro activated by Treponema denticolachymotrypsin‐like protease (Td‐CTLP), sodium hypochlorite (NaOCl, 1 mM, oxidant) or amino phenyl mercuric acetate (APMA, 1 mM).

In saliva of periodontitis‐affected individuals, MMP‐8 is found in multiple forms, that is, complexes, active and pro‐forms of neutrophilic and mesenchymal‐type MMP‐8, and especially 20–27 kDa fragments. The quantity of these fragments was elevated in both localized and generalized forms of periodontitis. Moreover, the tested activators (Td‐CTLP, NaOCl and APMA) activated inactive proMMP‐8, resulting in fragments of 20–27 kDa, in vitro, and salivary concentrations of T. denticola correlated significantly with salivary levels of fragmented MMP‐8.

The present results indicate that during the development and progression of periodontitis, MMP‐8 appears as activated and fragmented, and treponemal proteases most likely play role in this cascade.