mouth and dental disorders
Cavities
Risk factors for cavities
There are many risk factors for cavities: Plaque Tartar Defects in the tooth surface Sugary or acidic foods Too little fluoride in the teeth Reduced saliva flow (for example, due to medications, Radiation Therapy for Cancer , or systemic disorders that cause salivary gland dysfunction) Genetic factors Plaqueis a filmlike substance composed of bacteria, saliva, food debris, and dead cells that is continually being deposited on teeth. Tartar,also scientifically known as calculus, is hardened plaque. It may be white but is more often yellow and forms at the base of teeth. For tooth decay to develop, a tooth must be susceptible, acid-producing bacteria must be present, and nutrients (such as sugar) must be available for the bacteria to thrive and produce acid. A susceptible tooth has relatively little protective fluoride incorporated into the enamel or has pronounced pits, grooves, or cracks (fissures) that retain plaque. Poor oral hygiene that allows plaque and tartar to accumulate can accelerate this process. Although the mouth contains large numbers of bacteria, only certain types generate acid, which causes decay. The most common decay-causing bacteria areStreptococcus mutans. Only a generation ago, most people expected to go through old age with false teeth or no teeth at all. This expectation has changed greatly during the last several decades. Although nearly half of people 85 or older have none of their natural teeth, the likelihood of losing teeth with aging is steadily decreasing. There are several reasons for this change: improved nutrition, better access to dental care, and better treatment for tooth decay and periodontal disease. When teeth are lost, chewing is greatly hindered, and speaking becomes a challenge. The face looks dramatically different without the support teeth normally provide for the lips, cheeks, nose, and chin. People who have lost some or all of their teeth can still eat, but they tend to eat soft foods. Soft foods tend to be relatively high in carbohydrates and low in protein, vitamins, and minerals. Foods that are high in protein, vitamins, and minerals, such as meats, poultry, grains, and fresh fruits and vegetables, tend to be harder to chew. Consequently, older people who eat mainly soft foods may become undernourished. The nutrients that decay-causing bacteria need come from the person’s diet. When infants are put to bed with a bottle that contains anything but plain water, their teeth have prolonged contact with the formula, milk, or juice, which increases the likelihood of decay. Large amounts of sugar in the diet also provide food for the bacteria. Acid in the diet accelerates tooth decay. (For example, soft drinks, sports drinks, and energy drinks, all of which are commonly acidic, tend to promote tooth decay.) Reduced saliva flow due to medications or disorders (such as Sjögren Syndrome ) places people at greater risk of tooth decay. Older people often take medications that reduce saliva flow, increasing their risk of cavities. Some people have especially active decay-causing bacteria in their mouth. A parent may pass these bacteria to a child through kissing, sampling the child's food, or sharing eating utensils. The bacteria flourish in the child’s mouth after the first teeth come in and can then cause cavities. So, a tendency toward tooth decay that runs in families does not necessarily reflect poor oral hygiene or bad eating habits. These bacteria can also be spread (rarely) through social contact with people outside the family. Gum Recession also makes cavities more likely to develop because it can expose the roots of teeth, which are not protected by an outer enamel layer. Then bacteria can access the inner layers of the tooth more easily. Gum recession and a reduction in salivary flow make older people prone to root cavities. 