Transverse root fracture Healing can be done by :
Union of segments with hard tissue.
Bony ingrowth across the fracture line.
Interposition of connective tissue or fibrous tissue.
All of the Above.
Healing of Root Fracture
According to Andreasen and Hjorting-Hanson, transverse root fracture healing can be done by any one of the following ways:

Union of segments with hard tissue
Interposition of connective tissue or fibrous tissue (periodontal ligament)
Bony ingrowth across the fracture line
Non-union with associated interposition of granulation tissue.