Interstitial collagenases, including matrix metalloproteinase-1 (MMP-1) and -8 (MMP-8), serve as initiators of extracellular matrix destruction in periodontal disease. Collagenase activities are mainly regulated by tissue inhibitors of metalloproteinases (TIMPs). We tested the effects of inflammation on MMP-1 and MMP-8 gene expression in periodontal disease. To determine the relative abundance of these mRNAs in gingiva, we used a reverse transcription-polymerase chain reaction (RT-PCR) assay. Gingival biopsies were divided into 2 groups; a control group and an inflamed group with severe gingivitis or periodontitis. The MMP-1 mRNA levels were significantly elevated in inflamed gingiva, while the levels of the MMP-8 transcript were not different in the 2 groups and barely detectable by RT-PCR assay. The expression of the TIMP-1 gene was not altered, and remained higher than any of these other genes in both control and diseased gingivae. These results suggest that MMP-1 rather than MMP-8 may play an important role in the initiation of collagen degradation in periodontal disease. However, the possibility remains that MMP-8 plays an important role in periodontal tissue destruction, since the mRNA abundance and not the enzyme activity was assessed.

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By using several kinds of mouthrinse, its inhibitory effect on the early plaque formation was examined for clinical consideration.Eight adult volunteers aged 25 to 35 years old with apparently healthy gingiva showing no sign of periodontal disease were enrolled in this study. For 14 consecutive days prior to the initiation of study, tooth surface cleaning and oral hygiene instruction were performaed by a dentist. All of these mechanical cleaning manipulations were abandoned at the beginning of experiment and mouthrinsing was performedwith 10 ml of different mouthrinses for one minute a time, twice a day. At the beginning of experiment and again on Day 4, the tooth surface was totally examined by means of Silness and LOe's Plaque Index (PH) . After ecamination on Day 4, tooth surface cleaning by the dentist and brushing by the subject were restarted, followed by dincontinuation of tooth cleaning after 10 days and than mouthrinsing with other mouthrinsing agents for subsequent 4 days. Five kinds of mouthrinse were used for this purpose, including 1) distilled water (DW) , 2) 0.12% chlorhexidine (CHX) , 3) acid water prepared by an electrolysis (AW) , 4) 0.1% stannous fluoride (SnF2) and 5) 0.02% cetylpyridium chloride-containing mouthrinse ( Dentor Systema, Lion) (CPC) .Various regions such as whole tooth surface, maxilla, mandible, anterior teeth, premolar, molar, adjacent surface and buccolingual side were examined for comparison. The average PlI value was 0.75 for CHX, 1.21 for AW, 1.20 for SnF2, 1.55 for CPC and 1.61 for DW. A statistical significant differences was observed between CHX and other individual mouthrinses, between AW and CPC or DW as well as between SnF2 and CPC or DW.Further, concerning all mouthrinses examined, the PlI value for anterior tooth region was lower than those of premolar and molar regions and the value for buccolingual region was lower than that for adjacent surface.