(See Biology of the Mouth and Biology of the Teeth.)
With aging, taste sensation may diminish. Older people may find their food tastes bland so, for more taste, they may add abundant seasonings (particularly salt, which is harmful for some people) or they may desire very hot foods, which may burn the gums.
Older people may also have disorders or take drugs that affect their ability to taste. Such disorders include
- Infections in the mouth, nose, or sinuses
- Gum disease
- Mouth cancer
- Chronic liver or kidney disease
Drugs affecting taste include some drugs used to treat high blood pressure (such as captopril), high cholesterol (such as the statins), and depression.
Tooth enamel tends to wear away with aging, making the teeth vulnerable to damage and decay. Tooth loss is the major reason that older people cannot chew as well and thus may not consume enough nutrients. When older people lose their teeth, the portion of the jaw bone that held those teeth in place does not maintain its previous height and thus appears to waste away.
A modest decrease in saliva production occurs with age and can be decreased further by some drugs. The decrease in saliva causes dry mouth (xerostomia). The gums may get thinner and begin to recede. Xerostomia and receding gums increase the likelihood of cavities. Some experts also believe that xerostomia may make the lining of the esophagus more susceptible to injury.
Despite xerostomia and receding gums, many older people retain their teeth, especially people who do not develop cavities or periodontal disease. Older people who lose some or all of their teeth will likely need partial or full dentures and/or implants.
Periodontal disease is the major cause of tooth loss in adults. Periodontal disease is a destructive disease of the gums and supporting structures caused by the long-term accumulation of bacteria. It is more likely to occur in people with poor oral hygiene, in people who smoke, and in people with certain disorders, such as diabetes mellitus, poor nutrition, leukemia, or AIDS. Though rare, dental infections caused by bacteria can also lead to pockets of pus (abscesses) in the brain, cavernous sinus thrombosis, unexplained fevers, and endocarditis in people with specific severe heart abnormalities.