The alveolar bone is part of the maxillary bone and the mandibular bone surrounding the teeth forming the tooth socket. It forms with the eruption of teeth and disappears after the tooth is lost. It consists of the outer cortical plate, composed of Haversian bone and compacted bone lamellae, a central spongiosa, and an inner socket wall. It is in the cortical plate into which the principal fibers of the periodontal ligament are inserted, referred to as sharpeyd fibers. The dense bone is penetrated by many vascular channels which communicate between the trabecular bone and the PDL.
The tissue is composed of 65%inorganic and35%organic matter. The inorganics are calcium and phosphate ions and other minerals such as carbonates. The inorganic is mainly hydroxyapatite.90% of the organic bone comprises collagen components common type 1and five, while the rest is non-collagenous proteins.
The alveolar bone’s primary function is holding the teeth firmly in position and transferring the occlusal forces to the basal bone. It also provides vascular supply to PDL and cementum. The bone also has a function of protecting the permanent teeth and housing the deciduous ones.
The bone heals fractures like any other bone fracture. A few hours after fracture, the osteoprogenitor cells from the periosteum, endosteum, and bone marrow separate and migrate from the bone marrow to the injury site. A blood clot is formed between fractured bones and its frameworks for cell migration, then quickly populated by the immature estrogenic cells. The clot, which comprises platelets and outer cells derived from the blood, has various growth factors, including platelet-derived growth factor, insulin-like growth factor, fibroblast growth factors, and morphogenetic proteins. The growth factors are responsible for stimulating the cascade, which brings about bone formation. New blood vessels are formed to penetrate the clot within 24hrs. The callus is formed within a few days between the fracture fragments of the bone. It is an immature woven bone that develops gradually to the form of mature bone/.