Molar and dental alveolus

A molar in its alveolus (socket) is shown in this demineralized section. Humans have twelve molars which possess two to three roots, with the upper molars typically having three. The enamel is not retained in this section as a result of the decalcification process used during tissue preparation. 10x

The dental alveolus is the bony socket that surrounds the root of the tooth. The socket is form by alveolar bone which differentiates from ectomesenchymal stem cells of the dental follicle.

The dental alveolus is the bony socket that surrounds the root of the tooth. The socket is form by alveolar bone which differentiates from ectomesenchymal stem cells of the dental follicle.

Interradicular septa are ridges of alveolar bone that form between the roots of the tooth.

The crown of the tooth extends above the gum line and is covered by enamel. Enamel, which is digitally added this image, is not retained in this section as a result of the decalcification process used during tissue preparation.

The neck of the tooth is a narrow region where the enamel of the crown meets the cementum. It includes the dentino-enamel and dentino-cementum junctions.

Molars normally have two to three roots with the upper molars typically having three.

Enamel, consisting of about 95% calcium phosphate (hydroxyapatite), is the most mineralized tissue in the human body. It is not retained in this section as a result of the decalcification process used during tissue preparation.

Dentin is the first hard tissue deposited during tooth development. It makes up the bulk of the hard tissue of the tooth and is 70% mineralized. Dentin is deposited throughout life by odontoblasts that reside in the pulp cavity.

The darker contour lines of Owen result from disruptions in the regular pattern of dentin formation in the crown of the tooth. They indicate phases of hypomineralization resulting from metabolic disruptions during odontogenesis.

Cementum is the calcified tissue layer on the surface of the root that anchors the tooth to the tooth alveolus via the periodontal ligament. It also seals the ends of dentin tubules. Acellular cementum (arrows) forms a thin layer on the surface of the cervical two-thirds of the root. It is the first cementum and does not contain cells. Cellular cementum (rectangles) is found at the apical one-third of the root is thicker and contains cementocytes. It is produced throughout life in response to force or trauma.

The periodontal ligament develops from the ectomesenchymal stem cells of the dental follicle during root formation. The periodontal ligament functions to anchor the tooth into the socket, provide sensation and nutrition to the tooth, and to defend the tooth against infections that result in periodontal disease.

The gingiva (commonly called the gums) is composed of the epithelium and connective tissue that surround and support the tooth. The outer portion of the gingiva is formed by the masticatory mucosa, composed of stratified squamous moist, orthokeratinized or parakeratinized, epithelium and an underlying lamina propria. The highly interdigitated epithelial ridges and long connective tissue papillae firmly attach the epithelium to the lamina propria.