We utilized Atp6i deficient mice as an osteopetrosis disease model to study tooth root formation and found that Atp6i knockout mice exhibit disrupted tooth root formation with truncated HERS progression as well as marked decreases in odontoblast markers Dspp, Nfic, Nestin, Osx, and Col1a1. The gene discussed is TCIRG1; the disease is osteopetrosis.