Teeth

Teeth are hard, calcified structures in the jaws that enable chewing, speaking, and facial aesthetics. Adult humans typically have 32 teeth, including incisors, canines, premolars, and molars. In early life, most children develop 20 primary teeth that are eventually replaced by permanent teeth.

Each tooth has a crown, which is above the gum line, and one or more roots anchored in the jawbone by the periodontal ligament. The outer enamel is the hardest substance in the body, covering a softer dentin layer. Inside is the pulp chamber containing nerves and blood vessels. The root surface is covered by cementum, and the tooth is held in place by the periodontal ligament to the surrounding alveolar bone.

Incisors are sharp-edged for cutting, canines for tearing, premolars for tearing and grinding, and molars for grinding. Surfaces include buccal (cheek-side) or facial, lingual (tongue-side) or palatal, and occlusal chewing surfaces.

Teeth develop from calcified tissue in embryos and erupt in a characteristic sequence. Deciduous teeth usually erupt from about six months to three years and are gradually replaced by permanent teeth, which emerge from around age six into early adulthood. The dental formula describes the typical number of each type per quadrant.

Cavities result from tooth decay, while periodontal disease affects supporting structures. Prevention includes brushing with fluoride toothpaste, flossing, limiting sugary foods, and regular dental checkups. Good oral hygiene helps maintain tooth function and alignment.

Teeth vary in size and shape to suit diet and function across individuals and populations. They are part of the musculoskeletal and sensory systems and interact with the jaw joints and muscles during chewing.