Alveolar bone
The alveolar process, which is also referred to as the alveolar bone, is a thick ridge of bone which contains the sockets of the tooth on the jaw bones that hold the teeth in place. The bones which secure the teeth are called the maxilla and the mandible. The curved portion of each alveolar process on the jaw is the alveolar arch.
On the maxilla, the alveolar process is a ridge located on the inferior surface. In contrast, the mandible is a ridge on the superior surface. This makes up the thickest portion of the maxillae.
The alveolar process contains a region of compact bone adjacent to the periodontal ligament (PDL). When viewed on radiographs, this region is called the lamina dura. This area is attached to the cementum of the roots by the periodontal ligament. It is uniformly radiopaque or lighter. The integrity of the lamina dura is vital in the study of radiographs for pathological lesions.
The alveolar process contains a supporting bone which includes components such as fibers, cells, blood vessels, nerves, intercellular substances, and lymphatics.
The alveolar process is the lining of the tooth socket. It is also called the alveolus. While the alveolar process is comprised of compact bone, it can also be called the cribriform plate. This is due to the fact that it contains holes where Volkmann canals pass from the alveolar bone into the PDL. The alveolar bone proper may also be called the bundle bone because of the Sharpey fibers, a portion of the fibers which make up the PDL, are found here. Similar to the cemental surface, the Sharpey fibers located within the alveolar bone proper are inserted at a right angle or at 90 degrees. They are thicker in the diameter and fewer in number in comparison to the fibers in the cementum. Similar to the cellular cementum, Sharpey fibers in the bone are typically only partially mineralized at their periphery.
The alveolar crest is the most cervical rim which is associated with the alveolar bone proper. In healthy cases, the alveolar crest is slightly apical to the cementoenamel junction (CEJ) by approximately 1.5-2 mm. When they are health, the alveolar crests of the adjacent teeth are uniform in height along the jaw bone.
The supporting alveolar bone structure is comprised of both cortical and trabecular bone. The cortical bone, or cortical plates, contain plates of compact bone which are located on the facial and lingual surfaces of the alveolar bone. These cortical plates are typically about 1.5 to 3 mm thick over the posterior teeth. The thickness can vary drastically around the anterior teeth. The trabecular bone contains cancellous bone that is located between the alveolar bone proper and the plates of cortical bone. The alveolar bone which is present between the two neighboring teeth is the interdental septum or the interdental septum or bone.
Composition
Inorganic material: By weight, the alveolar bone is comprised of 67% inorganic material. The inorganic material is mainly composed of calcium and phosphate. The mineral content is primarily in the form of calcium hydroxyapatite crystals.
Organic material: The remaining alveolar bone is made up of 33% organic material. The organic material contains materials which are both collagen and non-collagenous. The cellular components of the bone contain osteocytes, osteoblasts, and osteoclasts.
- Osteoblasts are typically in a cuboidal and elongated shape. They synthesize bone proteins which are both collagenous and non-collagenous. These types of cells also contain a high level of alkaline phosphatase on the outer surface of their plasma membrane. The primary functions of osteoblasts include formation or bone through the synthesizing the organic matrix of bone, cell to cell communication and maintaining the bone matrix.
- Osteocytes are modified osteoblasts which have become entrapped in lacunae during the secretion of bone matrix. These canaliculi deliver oxygen and nutrients to the osteocytes through the blood. In addition, they remove metabolic waste products.
- Osteoclasts are large, multinucleated cells.