Among horizontal root fractures, which location carries the best prognosis?

Horizontal root fractures at the apical third have the best prognosis because: (1) The apical segment has an intact blood supply and the coronal portion retains most of the root length and crown support; (2) The fracture is far from the gingival sulcus, reducing bacterial contamination; (3) The periodontal ligament surrounding the apical fragment has good healing potential. Fractures at the coronal third have the worst prognosis because the fracture is close to the sulcus (bacterial contamination risk), the coronal segment lacks adequate root support, and mobility is greater. Middle third fractures have intermediate prognosis.