Periodontal Anatomy – Alveolar bone
The alveolar process, which is also called the alveolar bone, is a thickened ridge of bone containing the sockets of the teeth or dental alveoli. It is located on the jaw bones which hold the teeth. The tooth-bearing bones are called the maxilla and the mandible. The curved part of each alveolar process, which is located on the jaw, is the alveolar arch.
On the maxilla, the upper fixed bone of the jaw, the alveolar process is a ridge on the inferior surface. On the mandible, the lower jaw, it is a ridge on the superior surface. This structure makes up the thickest part of the maxillae.
The alveolar process also contains an area of compact bone, which is adjacent to the periodontal ligament (PDL). This is called the lamina dura when it is being viewed on radiographs. This portion is attached to the cementum of the roots via the periodontal ligament. It is also uniformly lighter. The integrity of the lamina dura is vital in the process of studying radiographs for pathological lesions.
The alveolar process has a supporting bone. Both contain the same components which includes fibers, cells, intercellular substances, nerves, blood vessels, and lymphatics.
The alveolar process is the lining of the alveolus or tooth socket. While the alveolar process is made up of compact bone, it may also be called the cribriform plate. This is because it contains holes where Volkmann canals pass from the alveolar bone and into the PDL. The alveolar bone proper may also be called bundle bone. This is because the Sharpey fibers, which are part of the fibers in the PDL, insert at this location. Similar to the fibers of the cemental surface, Sharpey fibers in the alveolar bone proper are inserted at 90 degrees. They are fewer in number, but thicker in diameter compared to those which are present in the cementum. Just as they are in the cellular cementum, the Sharpey fibers located in the bone are typically mineralized only partially at their periphery.
The alveolar crest is the most cervical rim included in the alveolar bone proper. In healthy cases, the alveolar crest is slightly apical to the cementoenamel junction (CEJ) by about 1.5-2 mm. The alveolar crests of the neighboring teeth should also be uniform in their height along the jaw.
The supporting alveolar bone contains both trabecular and cortical bone. The trabecular bone contains cancellous bone which is located between the alveolar bone proper and the cortical bone plates. The alveolar bone located between two neighboring teeth is the interdental septum. The cortical bone, or cortical plates, contains plates of compact bone on the alveolar bone’s facial and lingual surfaces. These cortical plates are typically about 1.5-3 mm thick over the posterior teeth. However, this thickness can drastically vary around the anterior teeth.
Composition - Inorganic Material
By weight, the alveolar bone is comprised of 67% inorganic material. The inorganic material mainly contains calcium and phosphate. The mineral content is primarily in the form of calcium hydroxyapatite crystals.
Composition - Organic Material
The remaining 33% of the alveolar bone is comprised of organic material. The organic material contains both collagen and non-collagenous material. The cellular component of the bone contains osteoblasts, osteocytes and osteoclasts.