Effects of salivary immune response to Streptococcus mutans on caries occurrence and caries development in mice with autoimmune disease.

MRL/l strain mice, which possess a lymphoproliferative gene inducing swelling of systemic lymph nodes, develop a SLE (systemic lupus erythematosus)-like syndrome at around 8 w of age. MRL/n mice, which carry 99.6% of the genes of MRL/l mice, lack the gene for lymphoproliferation and exhibit only a slight degree of lymph node swelling late in life. This study investigated whether the salivary immune response caused by Streptococcus mutans(S. mutans) infection prevented dental caries in MRL/l and MRL/n mice after 8 w of age. A total of 10 MRL/l mice and 10 MRL/n mice were fed a commercial pellet diet without sucrose until 74 d of age, and then fed Diet 2000 containing 56% sucrose ad libitum from 75 to 130 d of age. On d 75, both strains of mice were inoculated with S. mutans JC-2 for 7 d. At 130 d of age, saliva samples were collected and caries scores were assessed. The results obtained suggested that the salivary immune response was one of the most important factors regulating caries occurrence.