The role of bone remodelling in the healing of extraction socket in rats.

Bone remodelling of post-extraction socket was studied in the past by various methods. In the present work, the process was studied with the scanning electron microscope (SEM). The SEM is essential for a three-dimensional description, particularly when hard tissues are involved. Initiation of healing on the first week was characterized by formation of delicate spongy bone. The trabeculae were distributed in a centrifugal pattern around the interradicular bone. Socket healing on the second week consisted of thickened, regularly distributed trabeculae. This was accompanied by resorption and flattening of the peri-socket sharp ridges. The third and fourth weeks were characterized by small bone marrow spaces and a gradual transformation of the trabecular bone to one of cortical-compact nature. The typical characteristics of resorbing, resting and forming surfaces were detected in all phases of socket healing. Two major patterns of ossification could be shown: Firstly, calcification of collagen bundles in osteoblastic lacunae. Concentrations of such lacunae were related to periosteal activity and were also found in areas most probably occupied previously by blood vessels. Another pattern of mineralization was in the form of globular calcospherites and is reminiscent of calcification of ground substance.