[Effects of topical application of immunoglobulin yolk on mutans streptococci in dental plaque].

To evaluate the inhibitory effects of topical application of specific immunoglobulin yolk antibodies (IgY) to mutans streptococci on composition of human dental plaque.A total of 24 healthy adult volunteers were selected and randomly distributed into three experimental groups. After a supragingival scaling, the subjects were treated with an application of IgY containing spray (test group, n = 9), a 0.15% chlorhexidine(CH) spray(positive control group, n = 9) or a placebo phosphate buffered saline(PBS) spray without any active ingredients(negative control group, n = 6) three times daily for three weeks. Pooled plaque samples from the smooth surfaces of teeth were collected for microbiologic analysis before administration (baseline, day 0), during treatment(days 7, 14 and 21) and after withdrawal of the agents(days 28, 42 and 56) and plaque index were recorded. Microbial cultivation were performed by serially diluting the samples with PBS solution an cultivating the aliquots on mitis salivarius agar(MS) and MS supplemented with bacitracin (MSB) for oral streptococci and mutans streptococci respectively. The number of colony-forming unit (CFU) per plate was counted and the percentage of mutans streptococci per oral streptococci in dental plaque were determined. The effect of IgY on colonization of mutans streptococci were analyzed by an analysis of variance (ANOVA).The plaque indexes remained unchanged, but mutans streptococci in dental plaque was suppressed significantly following a short term(three weeks) application of IgY, and low level of mutans streptococci persisted for at least 5 weeks after withdrawal of IgY.The results suggest that the immunization with specific immunoglobulin yolk against mutans streptococci could be useful for long term suppression of mutans streptococci colonization in human dental plaque.