MMP20 and dental caries: Associations between number of prisms by square millimeter, prism density, and gap distance and markers in multiple genes previously associated with dental caries and enamel formation (Table 3) were found, including TUFT1, AMBN, KLK4, MMP20, ENAM, and DEFB1. Two outliers that were included in the initial association tests were removed and the resulting data is presented in Table 3.