Serum and salivary antibodies to Streptococcus mutans in relation to the development and treatment of human dental caries

Abstract

Antibodies to Streptococcus mutans and Streptococcus sanguis were examined in samples of serum and parotid saliva from 96 subjects, aged 18–24. Subjects were divided into groups based on the concept that any natural immunity would be best revealed by comparing subjects of low caries experience with subjects of high caries experience, and analysing separately subjects with carious lesions at the time of examination. Low caries experience was associated with significantly greater serum IgG and IgM antibodies but lower salivary IgA antibodies to Strep. mutans than high caries experience. In subjects with carious lesions serum IgG antibodies to Strep. mutans were significantly greater than in the matched high caries experience group, but salivary antibodies were lower. No differences in the antibody levels to Strep. sanguis were detected in the three groups. Sequential studies revealed that the development of caries was associated with a rise in serum IgG and IgM antibodies to Strep. mutans, but not to Strep. sanguis. Treatment of caries was associated with a fall in serum antibodies to Strep. mutans but a rise in salivary antibodies. The results suggest that Strep. mutans is closely associated with caries in man, but that Strep. sanguis is not. It is suggested that, in man, naturally induced serum IgG antibodies are associated with protection against caries, but that antibodies of the IgA class in serum or parotid saliva are not associated with protection. Serum IgG antibodies to Strep. mutans or Strep. sanguis showed an inverse relationship with salivary IgA antibodies, and changes in the salivary antibody titre were negatively correlated with changes in the serum IgG antibody titre.