Anatomy of the tooth

Articulating surfaces

The articulating surfaces on the most superior part of the crown of the teeth are designed to accommodate the function of the tooth through contact points with their respective antagonist teeth. The anterior teeth, including the incisors and canines, have a single incisal edge designed for specific functions: incisors cut food, while canines, through a prominent single cusp are designed to tear food. Posterior teeth, the premolars and molars, have broader, flatter surfaces called occlusal surfaces. These surfaces feature cusps, pits and fissures that allow premolars to tear and grind food, and the molars to grind and mash food.

Although the different types of teeth have unique appearances, their general composition is the same and consists of three main parts: crown, neck and roots.

Crown

Anatomically, the crown is described as being the part of the tooth that extends from the cusps or incisal edge to the cementoenamel junction (CEJ). Clinically, it is described as the visible or exposed part of the tooth in the oral cavity.

Its outermost layer is the enamel, the hardest substance in the human body. Enamel is primarily inorganic and composed mostly of hydroxyapatite crystals. It is typically pearl white or slightly yellow in appearance and serves as a durable chewing surface while protecting the underlying dentin from damage.

Dentin, a slightly softer and darker layer, lies beneath the enamel, providing it with support and separating it from the innermost pulp cavity. It contains microscopic tubules that transmit sensations, contributing to its sensitivity. The pulp cavity houses blood vessels, nerves and connective tissue, making it the most sensitive and vital part of the tooth.

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Neck

The neck of the tooth is located at the gum line, marking the junction between the crown, which is covered by enamel, and the root, which is covered by cementum. It is commonly identified as the region surrounding the CEJ, enclosing the underlying dentin and the pulp cavity.

Root

The root of the tooth is the portion located below the CEJ. It is anchored within the dental alveoli of the maxilla and mandible by the periodontium, which includes the periodontal ligament, cementum, and gingiva. The outer layer of the root is the cementum, akin to the enamel of the crown, overlaying the deeper dentin layer. The pulp chamber continues down from the crown into the root as the root canal, which contains the radicular pulp, ending at the apex of the root where there is an opening (apical foramen) that allows the structures of the pulp chamber to exit and enter.

Each tooth contains between one to three roots depending on its type and location. In both the mandible and maxilla, the incisors, canines, and the first premolars are generally single rooted. The maxillary second premolar may have two roots, while maxillary molars typically have three roots. The mandibular second premolar commonly has a single root, while molars tend to have two roots.