Wound healing and revascularization: a histologic observation of experimental tooth root fracture

We used dogs as an animal model to generate tooth root fracture and to observe the wound-healing process of the fracture. Histologic examination of the specimens revealed that the early reaction of the wound healing was infiltration of inflammatory cells particularly at the coronal part of the fracture, whereas less inflammation but more abundant collagen fibers were seen at the apical part of the fracture (15 and 30 days). Inflammation lasted for more than 90 days and then subsided. At day 180, bone tissue healing was observed. Revascularization of the pulp tissues reached a high level at the same stage that bone healing took place. Our data suggest that in tooth root fracture, the regeneration of blood vessels is important in the wound-healing process and the revascularization is synchronized with the fracture wound healing. In this animal model the complete hard tissue healing could take as long as 6 months.