A comparison of IgA antibody levels in caries-resistant and caries-susceptible children

Abstract

Secretory immunity is believed to play a role in natural resistance to dental caries. Although dental caries has dramatically decreased in children in the United States, there remains a population of caries-susceptible children even in fluoridated communities. Previous studies have shown a positive correlation between salivary immunoglobulin A (sIgA) antibody levels to Streptococcus mutans and caries resistance in adults. In the present study, an enzyme-linked immunosorbent assay (ELISA) was used to compare IgA antibody levels to S. mutans in saliva from 20 caries susceptible (DMFS greater than 5) and 20 caries-resistant (DMFS less than or equal to 1) children (ages 7-11). All subjects resided in fluoridated communities. Salivary S. mutans numbers were significantly higher (p ≤ 0.05) in the caries susceptible (31.2 percent of total streptococci) group than in the caries resistant (1.6 percent of total streptococci) group. Whole saliva from caries-resistant children had significantly higher (p = 0.05) levels of IgA antibodies to S. mutans than saliva from caries-susceptible children. However, whole saliva from caries-resistant children had similar levels of IgA1 or IgA2 antibodies against S. mutans to saliva from caries-susceptible children. These results suggest that IgA antibody to S. mutans may play a role in natural protection from dental caries in children and confirm previous reports indicating a role for salivary IgA antibodies to S. mutans in mediation of caries.