1Trope M, Chivian N, Sigurdsson A. Traumatic injuries [M]. //Cohen S, Burns RC, eds. Pathways of the pulp. St. Louis: Mosby, 1998:567-572.
2Chang HH, Wang YL, Chen H J, et al. Root fracture of immature permanent incisors-A case report [ J ]. Dent Traumatol, 2006, 22 (4) :218 - 220.
3Gungor HC, Buyukgtiral B, Uysal S. Root fracture in immature tooth : Report of a case [ J ]. Dent Traumatol, 2007, 23(3) :173 - 176.
4Cobankara FK, Ungor M. Spontaneously healed horizontal root fracture in maxillary first premolar: Report of a case [J]. Dent Traumatol, 2007, 23(2) :120 - 122.
5Hovland EJ. Horizontal root fractures : Treatment and repair[J]. Dent Clin North Am, 1992, 36(2) :509 -525.