<P> The alveolar crest is the most cervical rim of the alveolar bone proper . In a healthy situation, the alveolar crest is slightly apical to the cementoenamel junction (CEJ) by approximately 1.5 to 2 mm . The alveolar crests of neighboring teeth are also uniform in height along the jaw in healthy situation . </P> <P> The supporting alveolar bone consists of both cortical bone and trabecular bone . The cortical bone, or cortical plates, consists of plates of compact bone on the facial and lingual surfaces of the alveolar bone . These cortical plates are usually about 1.5 to 3 mm thick over posterior teeth, but the thickness is highly variable around anterior teeth . The trabecular bone consists of cancellous bone that is located between the alveolar bone proper and the plates of cortical bone . The alveolar bone between two neighboring teeth is the interdental septum (or interdental bone). </P> <P> The mineral content of alveolar bone is mostly calcium hydroxyapatite, which is similar to that found in higher percentages in both enamel and dentin, but is most similar to the levels in cementum (50%). Like all bone, mature alveolar bone is by weight 60% mineralized or inorganic material, 25% organic material, and 15% water . The minerals of potassium, manganese, magnesium, silica, iron, zinc, selenium, boron, phosphorus, sulfur, chromium, and others are also present but in smaller amounts . Alveolar bone is more easily remodeled than cementum, thus allowing orthodontic tooth movement . When viewing a stained histological section, the remodeled alveolar bone shows arrest lines and reversal lines, as does all bone tissue . </P> <P> The developmental disturbance of anodontia (or hypodontia, if only one tooth), in which tooth germs are congenitally absent, may affect the development of the alveolar processes . This occurrence can prevent the alveolar processes of either the maxillae or the mandible from developing . Proper development is impossible because the alveolar unit of each dental arch must form in response to the tooth germs in the area . </P>

Of what mineral are the hard tissues of the teeth and alveolar bone composed