In search of direct in vivo evidence of matrix metalloproteinases (MMPs) in periodontal tissue destruction, we studied the presence and localization of MMP-9 and neutrophil gelatinase-associated lipocalin (NGAL) in adult periodontitis (AP) and localized juvenile periodontitis (LJP) gingival tissue specimens by immunohistochemistry, and the activities of gelatinases by Western blot, enzymography, and activity measurements, using radioactive gelatin as substrate in gingival crevicular fluid (GCF) and saliva. In gingival tissue obtained from AP and LJP patients, polymorphonuclear leukocyte (PMN) 92-kDa MMP-9 and NGAL were seen in the connective tissue, but both the sulcular and the oral epithelia were consistently negative. Whereas PMNs located in the gingival blood vessels showed strictly cytoplasmic MMP-9 and NGAL immunoreactivities, in the case of PMN extravasation the staining reactions extended extracellularly. Gelatinase activities consisting mainly of 92-kDa gelatinase were increased in AP GCF relative to LJP GCF and periodontally healthy control GCF. Western blot with specific anti-NGAL antibodies revealed the presence of 25-kDa NGAL and its high-molecular-weight forms in AP and LJP GCF and saliva and in culture medium of oral keratinocytes, but not in gingival fibroblast culture medium. We conclude that extravasated degranulating PMNs are the major source of MMP-9 and NGAL in periodontitis gingiva, GCF, and saliva.

Dental plaque is the major aetiological factor in periodontal diseases and contains several proteolytic enzymes. The origin of these proteinases is, however, poorly studied. This study was undertaken to characterize collagenase present in dental plaque of adult periodontitis patients. Vertebrate-type rather than bacterial-derived collagenase activity was detected in extracts of both supra- and subgingival dental plaque extracts of adult periodontitis patients. Dental plaque collagenase was found to exist predominantly in autoactive form. Dental plaque collagenase from periodontally healthy individuals existed in latent from. Latent dental plaque collagenase from periodontitis lesions could be activated by a 95 kD chymotrypsin-like proteinase from Treponema denticola and human leukocyte cathepsin G but not by human plasmin. Incubation of purified latent leukocyte collagenase with whole cells of Fusobacterium nucleatum, Eubacterium saburreum, Prevotella buccae and Porphyromonas gingivalis, however, did not result to the activation of the enzyme. Doxycycline in vitro inhibited dental plaque collagenase with an IC50-value of 20 microM. Dental plaque collagenase degraded more efficiently type I and II collagens than type III collagen. Western-blot analysis with specific anti-human neutrophil collagenase-antibody revealed that both in supra- and subgingival dental plaque extracts dental plaque collagenase had undergone proteolytic conversion from an 80 kD proform to a 58 kD active form which is associated with catalytic autoactivity as measured by functional collagenase assay. This reflects proteolytic activation of leukocyte collagenase in dental plaque probably by other proteases derived from potent periodontopathogenic bacteria such as T. denticola or other PMN proteases such as cathepsin G.(ABSTRACT TRUNCATED AT 250 WORDS)

In a previous study, 800 mg pieces of sorbitol-flavored gum, each piece containing 5 mg chlorhexidine (CHX) acetate, when chewed 2 at the time 5 x daily, were found to have an excellent plaque growth inhibiting effect. The aim of Trial 1 of the present study was to assess whether chewing only 2 x daily, 2 pieces of the same concentration CHX gum for about 10 min would be as effective. 6 dental students participated in the 3 x randomly crossed over double-blind clinical trial. During the 5-day chewing periods, no other oral hygiene measures were allowed. The Hibitane Dental (HD) rinse was used as a positive and the gum base containing neither CHX nor the sweetening agent as a negative control. At the end of each test period, recordings were made for the plaque index (PII), the plaque wet weight (PWW) and the relative area of plaque covered tooth surface (plaque area %). Chewing of CHX gum twice daily inhibited plaque growth as effectively as the HD rinse. The aim of Trial 2 was to assess the antiplaque effect of lower concentration CHX gums with, hopefully, a less unpleasant taste. For this trial, 8 dental students were recruited to chew 2 x daily during 6-day periods two 800 mg pieces of sorbitol-flavored gum, each piece now containing either 5 mg, 4 mg or 3 mg CHX acetate. The effect of these dosages did not differ from the effect of the HD rinse.(ABSTRACT TRUNCATED AT 250 WORDS)