Human tooth
Hard structures that mechanically break down food for digestion.
Human teeth are hard, mineralized structures embedded in the upper jaw (maxilla) or lower jaw (mandible) and covered by gums. They are part of the digestive system, mechanically breaking down food by cutting, tearing, and crushing it for swallowing and digestion. Humans, like most mammals, are diphyodont, developing two sets of teeth over a lifetime. The first set, called deciduous, primary, baby, or milk teeth, normally consists of 20 teeth. These typically begin to erupt around six months of age, a process that can be distracting or painful for an infant, though some babies are born with visible neonatal or natal teeth. The permanent adult set usually comprises 32 teeth, with 16 in each jaw. The dental formula for permanent teeth is 2 incisors, 1 canine, 2 premolars, and 3 molars in each quadrant of the mouth. Third molars, commonly known as wisdom teeth, usually emerge between ages 17 and 25, but may never erupt or form at all; when they do, they often require removal. Additional teeth beyond the normal count are called supernumerary teeth (hyperdontia), while fewer than usual is termed hypodontia.
Teeth are classified into four types based on function: incisors cut food, canines tear it, and premolars and molars crush it. Anatomically, the crown is the part covered in enamel above the cementoenamel junction (CEJ), composed mostly of dentin with a pulp chamber inside. The root lies below the CEJ, covered by cementum, and also contains dentin and pulp canals. Canines and most premolars usually have one root, maxillary first premolars and mandibular molars typically have two, and maxillary molars usually have three. Enamel, the hardest and most mineralized substance in the body, originates from oral ectoderm and is 96% mineral, with the rest water and organic material. Its color ranges from light yellow to grayish white, sometimes appearing slightly blue at edges where no dentin lies beneath. Male teeth and jaws tend to be larger on average than female, with male teeth containing proportionately more dentin and female teeth more enamel.
- types
- Incisors, canines, premolars, molars
- primary_teeth_count
- 20
- permanent_teeth_count
- 32
- eruption_start
- Around six months of age
- dental_formula_primary
- 2.1.0.2 / 2.1.0.2
- dental_formula_permanent
- 2.1.2.3 / 2.1.2.3
Lore & Background
Human teeth are classified into four distinct types based on their function: incisors for cutting, canines for tearing, and premolars and molars for crushing and grinding food. The roots of these teeth are embedded in either the maxilla (upper jaw) or the mandible (lower jaw) and are covered by gums. Each tooth is composed of multiple tissues of varying density and hardness. The anatomic crown, covered in enamel, sits above the cementoenamel junction (the neck of the tooth), while the root below is covered with cementum. Most of both crown and root is made of dentin, with the pulp chamber inside the crown and pulp canals within the root. Canines and most premolars typically have one root, though maxillary first premolars and mandibular molars usually have two, and maxillary molars usually have three; extra roots are termed supernumerary. Humans are diphyodont, developing 20 deciduous (primary, baby, or milk) teeth and 32 permanent teeth. Primary teeth normally begin to erupt around six months of age, which can be painful for the infant, though some babies are born with visible neonatal teeth. The permanent set includes incisors, canines, premolars (also called bicuspids), and molars, with third molars (wisdom teeth) usually emerging between ages 17 and 25; these may never erupt or form at all, and when they do, they often require removal. Additional teeth beyond the usual count are called supernumerary, while fewer than normal is hypodontia. Male teeth and jaws tend to be larger on average than female ones, and male teeth contain proportionately more dentin, while female teeth have proportionately more enamel. Enamel, the hardest substance in the body, is 96% mineral and varies in color from light yellow to grayish white, with a slightly blue tone at edges lacking underlying dentin.
Reader's Guide
Human teeth are essential for the initial mechanical breakdown of food, a critical step in digestion. Their structure—with enamel as the hardest body substance, supported by dentin, cementum, and pulp—allows them to withstand years of chewing. The study of dental anatomy aids dentists in identifying and treating teeth. Differences exist between male and female teeth, with male teeth and jaws tending to be larger and male teeth having proportionately more dentin, while female teeth have more enamel. Notation systems like the FDI World Dental Federation notation, Universal Numbering System, and Palmer notation help standardize tooth identification globally.
Did You Know?
- Enamel is the hardest and most highly mineralized substance in the human body, composed of 96% mineral.
- Humans usually have 20 primary teeth and 32 permanent teeth.
- Third molars, or wisdom teeth, usually emerge at ages 17 to 25 and may never erupt or form at all.
- Male teeth tend to be larger on average than female teeth, with proportionately more dentin.
More in Human Anatomy 1-24
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