Preventive Effect of Intraoral Treatment by Antibody Against Purified Surface Antigen from S. Mutans on Experimental Dental Caries

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Surface protein antigen (SAI/II) from S. mutans was purified and resolved to a lower-molecular-weight protein. The purified antigen was mainly composed of 100KDa- and 50KDa- proteins, and a trace amount of some lower-molecular proteins. These lower-molecular proteins also reacted With anti-SAI/II antibody. Anti-SAI/II antibody reacted with antigens from S. mutans (serotype a, c-h), S. sanguis, S. salivarius and S. mitior.Adsorption of S. mutans cells which treated IgG fraction of antibody to hydroxyapatite (HA) was inhibited by 87, 73, 70 and 95% by treatment of cells with crude, SAI/II, SA 100KDa antibodies, respectively. Pretreatment of HA with purified and SAI/II antibodies was inhibited by 21 and 11%, respectively.The incidence of caries in rats infected with S. mutans PA-14 (c) and fed diet containing 6% of anti-SAI/II antibody was significantly lower (p<0.05) than in rats infected with the same strain and receiving diet containing 6% of normal serum. The mean caries score was reduced by 47.7%.The Intraoral Cariogenicity Test (ICT) appliances mounted with enamel slabs were placed in the human mouth of volunteers. The sections of the appliance carrying the test enamel-slab were immersed extraorally 3 times daily, in a vessel containing sucrose solution followed by in a two-compartment vesssel containing anti-SAI/II antibody solution in one compartment and normal serum solution in the other. Enamel demineralization was assessed by measuring the change of enamel microhardness at the beginning and at the end (2 weeks later) of the experiment. The mean (<plus-minus> SE) demineralization value of the control group was 200 ([>SY.+-.[) 3.9 and that of experimental group was 242 <plus-minus> 4.9. The difference between these values was significant at the 0.05 le