On the other hand, previous studies have shown that elevated salivary IgA levels are associated with decreased dental caries activity, and that s-IgA production provides a local defense with regards to dental infection.22,23 Brandtzaeg24 suggested that elevated IgA levels are a protective response to reduce dental caries, and also indicated that large numbers of carcinogenic bacteria in untreated necrotic lesions could stimulate an immune response and increase salivary IgA levels in the mouth. This evidence concerns the gene CD79A and dental caries.