THE EFFECT OF A MOUTHRINSE BASED ON NISIN, A BACTERIOCIN, ON DEVELOPING PLAQUE AND GINGIVITIS IN BEAGLE DOGS

The aim of this study was to evaluate the effect of nisin, an antimicr obial peptide, on the development of plaque and gingivitis in beagle d ogs when compared with 0.12% chlorhexidine and a placebo. 16 female be agle dogs 1 year of age were brought to optimum gingival health by sca ling, root planing and polishing. At the conclusion of the pretreatmen t phase, the dogs were divided into 4 groups for the application of th e test agents and were placed on a plaque promoting diet of Purina Dog Chow softened with water. Test agents included 100 mug/ml nisin and 3 00 mug/ml nisin formulated in a vehicle containing 1 mM NaEDTA; negati ve control comprised of exactly the same formulation but omitting nisi n; and 0.12% chlorhexidine as Peridex(R). Throughout the treatment per iod, formulations were applied 2 x daily to premolar teeth in each qua drant for 1 min using a Monojet syringe. The development of plaque and gingivitis was monitored at 15, 27, 39, 53, 74 and 88 days during the treatment phase using standard measurements of gingival index, plaque index, stain index and bleeding to probing. Throughout the treatment phase, plaque accumulation increased in all groups, but the rate of pl aque build-up was less in groups treated with either nisin or chlorhex idine formulations compared with the placebo treated group. The gingiv al index of dogs in all groups increased throughout the study period. However, from day 27 onward, the groups receiving nisin had lower ging ival index scores than did the placebo group. At day 39 and onward, th e chlorhexidine group had significantly lower gingival index scores th an the placebo group. All groups demonstrated an increased in % bleedi ng sites. However, from day 27 onward, the 300 mug/ml nisin group and from day 39 the 100 mug/ml group, had significantly fewer % bleeding s ites than the placebo group. An evaluation of the staining intensity i ndex revealed that staining for the chlorhexidine-treated group was si gnificantly greater than that of placebo and nisin at days 27, 74 and 88. In conclusion, nisin is an antimicrobial agent and is effective in the reduction of plaque build-up and gingivitis in the beagle dogs.