Low Biofilm Lysine Content in Refractory Chronic Periodontitis.

Abstract

BACKGROUND: Chronic periodontitis is controlled without antibiotics by scaling and root planing (SRP) to remove dental biofilm. We previously reported that the epithelial barrier to bacterial proinflammatory products is impaired when biofilm lysine falls below the minimal content of normal blood plasma. We therefore examined whether low biofilm lysine contents were associated with being refractory and requiring antibiotics to supplement SRP therapy. METHODS: Sixteen periodontitis patients and 6 periodontally healthy volunteers (HV), respective mean ages 57+/-6 and 36+/-8 years, were examined. Periodontitis patients received SRP and surgery, and HV received prophylaxis. At quarterly maintenance/prophylaxis visits during the subsequent year, therapeutic response was good (GR, n=9) or poor (PR, n=7; 5 cigarette smokers). Biofilm cadaverine, lysine and other amino acid (AA) contents were determined by liquid chromatography. Cadaverine mole fraction of lysine plus cadaverine (CF) indicated biofilm lysine decarboxylase activity. RESULTS: Biofilm lysine was 0.19+/-0.10 and 0.20+/-0.09 mumol/mg in GR and HV, but 0.07+/-0.03 mumol/mg in PR (Kruskal-Wallis p< 0.01). All AAs were depleted in biofilm from smokers, but only lysine in biofilm from non-smokers. CF was inversely associated with clinical attachment level (CAL) at baseline before therapy in all patients (R2=0.28, p<0.01) and with CAL change after therapy in GR (R2=0.49, p<0.05). Lysine and cadaverine contents discriminated PR from GR and HV (Wilks' Lambda=0.499, p <0.012). CONCLUSIONS: Refractory responses requiring antibiotic therapy result from smoking and/or microbial infections that starve the biofilm and epithelial attachment of lysine. Biofilm CF associates with periodontitis severity pre-therapy and extent of therapeutic response post-therapy.