Influence of salivary mutans streptococci level and HLA gene polymorphisms to dental caries susceptibility

The aim of this study was to examine the relation between levels of salivary mutans streptococci and HLA gene polymorphisms in dental caries-resistant and caries-susceptible human subjects. We analyzed HLA alleles at the HLA loci (DRB1, DQA1, and DQB1) in 89 subjects. Thirty-two subjects had high caries susceptibility, and 57 subjects were caries free. Salivary levels of mutans streptococci were measured with a strip mutans test. Comparisons of salivary mutans streptococci levels between certain allele positive and negative and between caries-resistant and caries-susceptible subjects were tested by means of Mann-Whitney U-test. In caries-resistant or caries-susceptible subjects there were significant differences of salivary mutans streptococci levels between positive allele and negative allele in HLA-DQB1*05 (p = 0.01), DRB1*01 (p = 0.02), DRB1*14 (p = 0.04), DQA1*01 (p = 0.007), and DQA1*04 cluster (p = 0.01), respectively. Moreover, we found significant difference of salivary mutans streptococci levels in HLA-DRB1*04, *08, *09, and *12 alleles between two dental caries statuses, respectively. On the other hand, we did not find such difference in HLA-DRB1*01, *13, *14, and *15 alleles.