Diseases and disturbances of the teeth and associated structures, including abnormal formation and growth of the teeth and jaws, tooth decay, inflammation of the tissues housing the roots of the teeth, and various diseases of the jaw bones.
Defective formation of dentin and enamel are referred to respectively as dentinogenesis and amelogenesis imperfecta, and may be caused by febrile illness during the period of tooth formation, or by faulty calcium or phosphorus metabolism, such as occurs in rickets. Some or all of the teeth may fail to form completely, or extra or supernumerary teeth may be present.
In most societies, dental decay, or caries, is one of the most important and common tooth disorders. Decay occurring during the adolescent years is caused by a class of microorganisms referred to as the cariogenic streptococci, of which Streptococcus mutans is a predominant member. However, a susceptible host and a cariogenic diet containing sucrose are also essential factors. Although the mechanism by which bacteria cause decay is not completely understood, most experts believe that cariogenic organisms, by using sucrose, and to a lesser extent other sugars, produce polymers which bind the organisms to the tooth surface and acids which cause demineralization resulting in cavity formation. Fluoride administration, either in the drinking water or by other routes, effectively reduces dental decay about 50–70%. The mechanism by which fluoride causes decreased decay rates is not understood.
Whereas dental decay is the principal cause of tooth loss in young individuals, inflammatory disease of the tissues surrounding the teeth, referred to as periodontal disease, causes most of the tooth loss in adults. See also Periodontal disease.
Diseases of the jaws may affect the teeth. The most common jaw disorders fall into four categories: (1) inflammation of the jawbone caused by infections such as osteomyelitis; (2) cysts associated with the teeth as well as those located in bone sutures of the jaws; (3) benign and malignant tumors of the jaws; and (4) systemic diseases such as generalized skeletal abnormalities produced by endocrine disfunction in which the jaws are affected. See also Dentistry; Tooth.
