Compensatory levels of salivary IgM anti-Streptococcus mutans antibodies in IgA-deficient patients.

The protective role of salivary IgA in dental caries has not been completely demonstrated, so, in order to elucidate this point, we evaluated 15 totally and partially IgA-deficient children in terms of the following variables: dental caries indexes, bacterial plaques, number of Streptococcus mutans and Lactobacillus in the saliva, and titers of IgA, IgG and IgM anti-Streptococcus mutans antibodies in the saliva. Age-matched healthy children served as the control group. IgA-deficient children showed caries scores lower than those of the healthy children; in addition, no statistical difference was found between amount of dental plaque and numbers of the bacteria in saliva. The totally IgA-deficient children presented IgM in levels much higher than the healthy children (p < 0.05). These data could indicate a compensation for the IgA deficiency by IgM.