New sustained release dosage form of chlorhexidine for dental use: II. Use in periodontal therapy

This study was carried out to examine the release kinetics of chlorhexidine from a sustained release device (S. R. D.) prepared from ethyl cellulose (fast S. R. D.) or ethyl cellulose with polyethylene glycol (slow S. R. D.) and to examine the effects on the bacterial flora of pockets in patients with periodontal disease. It was shown that fast S. R. D.'s release up to 80% of the chlorhexidine within the first 3 days in insertion in periodontal pockets, whereas the slow S. R. D.'s release 50% of the chlorhexidine content after 6 days. The release kinetics of chlorhexidine from S. R. D.'s placed in pockets as expressed by the Higuchi system (Higuchi 1963) indicate that it is diffusion controlled. The rate of chlorhexidine release is dependent on the structure of S. R. D., the drag concentration within the device, and the effective surface area. The microbial flora of sixteen pockets from 6 patients were examined using darkfield microscopy at day 0, 3, 10, and 14 after treatment with S. R. D.'s containing, chlorhexidine or placebo S. R. D.'s. The pocket depths ranged from 5–8 mm. The chlorhexidine‐treated group showed a marked decrease in the relative proportions of motile rods and spirochetes and a corresponding increase in non‐motile organisms compared to the flora prior to chlorhexidine treatment or compared to the flora of the placebo treated pockets. These differences were significant up to 10 days post treatment (P < 0.0025). The study indicated the effectiveness of ethyl cellulose polymers as S. R. D.'s in vivo and their ability to reduce the relative proportions of the motile organisms of periodontal pockets to negligible amounts.