Teeth - Anatomy of the Tooth

The teeth are hard structures, set in the upper or lower jaw, and are used for chewing food. Teeth also give shape to the face and aid in the process of speaking clearly.

Primary (baby) teeth usually appear between the ages of six months and three years and start to be replaced at about six years of age. During teething, a baby may be irritable, fretful, clinging, have difficulty sleeping and cry more than usual. Extra saliva may cause the child to dribble and a baby tends to chew on...

Anatomy Explorer

Full Teeth - Anatomy of the Tooth Description

[Continued from above] . . . anything he or she can hold. The gum may become red and swollen and the cheeks may be warm and red in the area in which the tooth is coming out.

We are born with the beginning of our permanent teeth already in place under the gums below the primary teeth. To neglect baby teeth is to invite a lifetime of dental problems, because as a child matures, the baby teeth guide the growth and development of the jawbones and of the permanent teeth. If the primary teeth are lost too early, the jaw may not develop correctly and the permanent teeth may come in crooked or overcrowded.

The second set of teeth, called secondary or permanent teeth, consists of thirty-two teeth-sixteen in each jaw-and they are arranged from the midline of the mouth as follows: central incisor, lateral incisor, cuspid, first bicuspid (premolar), second bicuspid, first molar, second molar, and third molar.

Adult teeth form very slowly and push up through the gums when they are fully formed. Permanent molars (grinding teeth) appear behind the primary premolars, where a child has no teeth at all. Eight bicuspids dislodge and take up the space of the eight primary molars, and adult incisors and cuspids (sharp, chisel-shaped, biting teeth) replace baby teeth of the same kind. When baby teeth fall out, the roots are absorbed into the gums. The first permanent teeth are frequently known as six-year-molars, because they appear at around that age. The process of shedding baby teeth begins at about that time too, with the front teeth as the first to go. The upper canines are the last baby teeth to be lost. By the age of eleven to thirteen, twenty-eight permanent teeth are usually in place. The four additional adult, or wisdom, teeth appear several years later; or, sometimes, they do not appear at all. Sometimes these molars, called wisdom teeth, become wedged in abnormal positions within the jaws and fail to erupt. Such teeth are said to be impacted.

Different teeth are adapted to handle food in different ways. Incisors (front teeth) are chisel-shaped, and their sharp edges bite off relatively large pieces of food. The cuspids (canine teeth) are cone-shaped, and they are useful in grasping or tearing food. The bicuspids and molars have somewhat flattened surfaces and are specialized for grinding food.

The enamel that covers the crown, the part above the gum, in each tooth can be broken down by acids produced by the mouth for digestive purposes. This process is called decay. To prevent decay, good oral hygiene, consisting of daily brushing and flossing, is necessary. The hardest substance in the human body is one of the four kinds of tissue that make up the tooth. It is enamel and covers the crown, the area above the gum line, of the tooth. A bony material called cementum covers the root, which fits into the jaw socket and is joined to it with membranes. Dentin is found under the enamel and the cementum, and this material forms the largest part of the tooth. At the heart of each tooth is living pulp, which contains nerves, connective tissues, blood vessels and lymphatics. When a person gets a toothache, the pulp is what hurts.