Genetic- and Lifestyle-dependent Dental Caries Defined by the Acidic Proline-rich Protein Genes PRH1 and PRH2

Dental caries is a chronic infectious disease that affects billions of people with large individual differences in activity. We investigated whether PRH1 and PRH2 polymorphisms in saliva acidic proline-rich protein (PRP) receptors for indigenous bacteria match and predict individual differences in the development of caries. PRH1 and PRH2 variation and adhesion of indigenous and cariogenic (Streptococcus mutans) model bacteria were measured in 452 12-year-old Swedish children along with traditional risk factors and related to caries at baseline and after 5-years. The children grouped into low-to-moderate and high susceptibility phenotypes for caries based on allelic PRH1, PRH2 variation. The low-to-moderate susceptibility children (P1 and P4a^-) experienced caries from eating sugar or bad oral hygiene or infection by S. mutans. The high susceptibility P4a (Db, PIF, PRP1₂) children had more caries despite receiving extra prevention and irrespective of eating sugar or bad oral hygiene or S. mutans-infection. They instead developed 3.9-fold more caries than P1 children from plaque accumulation in general when treated with orthodontic multibrackets; and had basic PRP polymorphisms and low DMBT1-mediated S. mutans adhesion as additional susceptibility traits. The present findings thus suggest genetic autoimmune-like (P4a) and traditional life style (P1) caries, providing a rationale for individualized oral care.