Based on the phenotypic differences, the dental defects caused by DSPP mutations may be classified into dentinogenesis imperfecta (DGI) Type II (OMIM #125490), characterized by pulp chamber obliteration, DGI Type III (OMIM #125500), featured by pulp chamber enlargement and thinner dentin, and dentin dysplasia (DD) Type II (OMIM #125420), which manifests relatively mild dental defects (Shields et al., 1973; MacDougall et al., 2006; Kim and Simmer, 2007). The gene discussed is DSPP; the disease is dentinogenesis imperfecta.