New population of odontoblasts responsible for tooth root formation.

•We identified and characterized apical odontoblasts for the formation of tooth roots.•Apical odontoblasts are differentiating odontoblasts, located in the apical side of developing roots.•Several transcription factors are temporospatially expressed in apical odontoblasts.•Apical odontoblasts may be easily damaged to genetic alteration as well as irradiation.