Teeth - function and definition
Calcified formations that grow from the gums in the MOUTH. The teeth are necessary for cutting, tearing, and chewing the food as well as for forming the sounds of language. A person develops two sets of teeth during his or her lifetime. The first set, the primary teeth, erupts around six months of age and remains in place until six or seven years of age. Then the permanent teeth begin to push through the gum and the primary teeth fall out. There are 20 primary teeth and 32 permanent teeth by adulthood. The last 4 permanent teeth, molars in the back of the mouth called the wisdom teeth, erupt through the gumline at age 18 to 20.
When a blow to the face knocks out a tooth, retrieve the tooth and put it in a plastic bag with ice. The dentist often can put the tooth back in place and the tooth will reroot.
The outer layer of the tooth, the enamel, is the densest, hardest substance in the body. Highly mineralized, enamel cannot replace itself when damaged. At the core of the tooth is one of the softest, the pulp. The pulp encases and nourishes the NERVE. Between the enamel and the pulp is a layer of calcified tissue almost as hard as BONE, the dentin. The tooth’s root extends from the jawbone. The main health condition to affect the teeth is DENTAL CARIES, or cavities. A cavity is a hole through the enamel that allows BACTERIA to enter the tooth. The bacteria eat away at the tooth’s inner structure until reaching the pulp, at which point the cavity causes PAIN. A dentist can plug a cavity with a resin filler to stop the process and preserve the tooth. Other health conditions that can affect the teeth include GINGIVITIS, PERIODONTAL DISEASE and traumatic injury.
See also HALITOSIS; GLOSSITIS; SIALADENITIS.
