Therefore, if a patient has a dental phenotype of DGI Types II or III or DD Type II without other non-oral symptoms, especially OI-related symptoms, the primary candidate gene to suspect is DSPP. Candidate gene sequencing of DSPP is not easy, especially for the last exon 5, which encodes part of the dentin sialoprotein (DSP) and the entire dentin phosphoprotein (DPP). Here, DSPP is linked to dentinogenesis imperfecta.