Tooth decay

Tooth Decay 2254
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Tooth decay, which is also called dental cavities or dental caries, is the destruction of the outer surface (enamel) of a tooth.


Tooth decay results from the action of bacteria that live in plaque. Plaque is a sticky, whitish film formed by a protein in saliva (mucin) and sugary substances in the mouth. The plaque bacteria sticking to tooth enamel use the sugar and starch from food particles in the mouth to produce acid, which destroys the tooth's enamel.

Baby bottle tooth decay

Baby bottle tooth decay is a dental problem that develops in infants, especially infants that are put to bed with a bottle containing a sweet liquid. Baby bottle tooth decay is also called nursing-bottle caries and bottle-mouth syndrome. Bottles containing liquids such as milk, formula, fruit juices, sweetened drink mixes, and sugar water continuously bathe an infant's mouth with sugar. The bacteria in the mouth use this sugar to produce acid that destroys the child's teeth. The upper front teeth are typically the ones most severely damaged; the lower front teeth are protected to some degree by the tongue. Pacifiers dipped in sugar, honey, corn syrup, or other sweetened liquids also contribute to baby bottle tooth decay. The first signs of damage are chalky white spots or lines across the teeth. As decay progresses, the damage to the child's teeth becomes more obvious.


Tooth decay is a common health problem, second in prevalence only to the common cold . It has been estimated that 90 percent of people in the United States have at least one cavity and that 75 percent of people had their first cavity by the age of five. Although anyone can have a problem with tooth decay, children are at particularly high risk. The good news is the number of children with cavities in the United States went down in the last few decades of the twentieth century. Some estimates are that as of the early 2000s cavities among adolescents have been reduced by nearly 40 percent. This rate decrease is explained in part by the fact that more areas have added fluoride to their drinking water and more children get regular, good dental care. However, children still drinking from a bottle anytime after their first birthday are more likely to have tooth decay.

Causes and symptoms

Tooth decay requires the simultaneous presence of three factors: plaque bacteria, sugar, and a vulnerable tooth surface. Although several microorganisms found in the mouth can cause tooth decay, the primary disease agent appears to be Streptococcus mutans . The simple sugars used by the bacteria are glucose, sucrose, and lactose. They are converted primarily into lactic acid. When this acid builds up on an unprotected tooth surface, it dissolves the minerals in the enamel, creating holes and weak spots (cavities). As the decay spreads inward into the middle layer (the dentin), the tooth becomes more sensitive to temperature and touch. When the decay reaches the center of the tooth (the pulp), the resulting inflammation (pulpitis) produces a toothache .

When to call the doctor

If a child complains of tooth or jaw pain and his or her cheek is swollen, and if he or she has a fever over 100°F (37.8°C), a dentist should be called right away. A dentist should be called during normal business hours if the child has tooth or jaw pain for more than a day, if white spots are noticed on an infant's teeth, or if there appear to be any other problems with the teeth or gums.


Tooth decay develops at varying rates. It may be found during a routine six-month dental checkup before the individual is even aware of a problem. In other cases, the individual may experience common early symptoms, such as sensitivity to hot and cold liquids or localized discomfort after eating very sweet foods. The dentist or dental hygienist may suspect tooth decay if a dark spot or a pit is seen during a visual examination. Front teeth may be inspected for decay by shining a light from behind the tooth. This method is called transillumination. Areas of decay, especially between the teeth, will appear as noticeable shadows when the teeth are transilluminated. X rays may be taken to confirm the presence and extent of the decay. The dentist then makes the final clinical diagnosis by probing the enamel with a sharp instrument.

Tooth decay in pits and fissures may be differentiated from dark shadows in the crevices of the chewing surfaces by a dye that selectively stains parts of the tooth that have lost mineral content. A dentist can also use this dye to tell whether all tooth decay has been removed from a cavity before placing a filling.

Damage caused by baby bottle tooth decay is often not diagnosed until the child has a severe problem, because many parents do not schedule regular dental exams for their small children. It is recommended that a child's first trip to the dentist be before one year of age and that trips to the dentist occur regularly every six months after that.


To treat most cases of tooth decay in older children, the dentist removes all decayed tooth structure, shapes the sides of the cavity, and fills the cavity with an appropriate material, such as silver amalgam or composite resin. The filling is put in to restore and protect the tooth. If decay has attacked the pulp, the dentist or a specialist called an endodontist may perform root canal treatment and then cover the tooth with a crown.

In cases of baby bottle tooth decay, the dentist must assess the extent of the damage before deciding on the treatment method. If the problem is caught early, the teeth involved can be treated with fluoride, followed by changes in the infant's feeding habits and better oral hygiene . Primary teeth with obvious decay in the enamel that has not yet progressed to the pulp need to be protected with stainless steel crowns. Fillings are not usually an option in small children because of the small size of their teeth and the concern of recurrent decay. When the decay has advanced to the pulp, pulling the tooth is often the treatment of choice. Unfortunately, loss of primary teeth at this age may hinder the young child's ability to eat and speak. It may also have negative effects on the alignment and spacing of the permanent teeth when they come in.


With timely diagnosis and treatment, the progression of tooth decay can be stopped relatively painlessly. If the pulp of the tooth is infected, the infection may be treated with antibiotics prior to root canal treatment or extraction. The longer the decay goes untreated, however, the more destructive it becomes and the longer and more intensive the necessary treatment will be. In addition, an individual with two or more areas of tooth decay is at increased risk of developing additional cavities.


It is easier and less expensive to prevent tooth decay than to treat it. The four major prevention strategies are proper oral hygiene, fluoride, sealants, and attention to diet.

Oral hygiene

The best way to prevent tooth decay is to brush the teeth at least twice a day, preferably after every meal and snack, and floss daily. Cavities develop most easily in spaces that are hard to clean. These areas include surface grooves, spaces between teeth, and the area below the gum line. Effective brushing cleans each outer tooth surface, inner tooth surface, and the horizontal chewing surfaces of the back teeth, as well as the tongue. Flossing once a day helps prevent gum disease by removing food particles and plaque at and below the gum line, as well as between teeth. Patients should visit their dentists every six months for oral examination and professional cleaning.

Parents can easily prevent baby bottle tooth decay by not allowing a child to fall asleep with a bottle containing sweetened liquids. If a bottle is necessary when the child is falling asleep it should be filled only with plain, unsweetened water. The child should be introduced to drinking from a cup around six months of age and usually weaned from bottles by 12 months. If an infant seems to need oral comfort between feedings, a pacifier specially designed for the mouth may be used. Pacifiers, however, should never be dipped in honey, corn syrup, or other sweet liquids.

After the eruption of the first tooth, parents should begin routinely wiping the infant's teeth and gums with a moist piece of gauze or a soft cloth, especially right before bedtime. Parents may begin brushing a child's teeth with a small, soft toothbrush at about two years of age, when most of the primary teeth have come in. They should apply only a very small amount (the size of a pea) of toothpaste containing fluoride. Too much fluoride may cause spotting (fluorosis) of the tooth enamel. As the child grows, he or she will learn to handle the toothbrush, but parents should control the application of toothpaste and do the follow-up brushing until the child is about seven years old.

Fluoride application

Fluoride is a natural substance that slows the destruction of enamel and helps to repair minor tooth decay damage by remineralizing tooth structure. Toothpaste, mouthwash, fluoridated public drinking water, and vitamin supplements are all possible sources of fluoride. Children living in areas without fluoridated water should receive 0.25 mg/day of fluoride before age three, 0.5 mg/day of fluoride from three to six years of age, and 1 mg/day after age six. Sometimes children can also have their teeth treated with fluoride at the dentist's office.

Tooth decay is the destruction of the outer surface, or enamel, of a tooth. It is caused by acid buildup from plaque bacteria, which dissolve the minerals in the enamel and create cavities. (Illustration by Electronic Illustrators Group.)
Tooth decay is the destruction of the outer surface, or enamel, of a tooth. It is caused by acid buildup from plaque bacteria, which dissolve the minerals in the enamel and create cavities.
(Illustration by Electronic Illustrators Group.)


Because fluoride is most beneficial on the smooth surfaces of teeth, sealants were developed to protect the irregular surfaces of teeth. A sealant is a thin plastic coating that is painted over the grooves of chewing surfaces to prevent food and plaque from being trapped there. Sealant treatment is painless, because no part of the tooth is removed, although the tooth surface is etched with acid so that the plastic will adhere to the rough surface. Sealants are usually clear or tooth-colored, making them less noticeable than silver fillings. They cost less than fillings and can last up to 10 years, although they should be checked for wear at every dental visit. Children should get sealants on their first permanent "six-year" molars, which come in between the ages of five and seven, and on the second permanent "12-year" molars, which come in between the ages of 11 and 14. Sealants should be applied to the teeth shortly after they erupt, before decay can set in. Although sealants have been used in the United States for about 25 years, one survey by the National Institute of Dental Research reported that fewer than 8 percent of American children have them.


The risk of tooth decay can be lowered by choosing foods wisely and eating less often. Foods high in sugar and starch, especially when eaten between meals, increase the risk of cavities. The bacteria in the mouth use sugar and starch to produce the acid that destroys the enamel. The damage increases with more frequent eating and longer periods of eating. For better dental health, children should eat a variety of foods, limit the number of snacks, avoid sticky and overly sweetened foods, and brush often after eating. Drinking water is also beneficial for rinsing food particles from the mouth. Children can be taught to rinse their mouth out with water after eating if they are unable to brush after lunch at school.

Parental concerns

If tooth decay is not treated, it can result in other, more serious, problems involving the gums, cheeks, or jaw. Baby bottle tooth decay that is not treated quickly can result in the affected teeth being removed. Although the child will eventually develop adult teeth to replace the baby teeth, missing baby teeth can result in overcrowding when the adult teeth come in. Missing baby teeth can also result in the adult teeth coming in crooked, the child having to chew on one side of his or her mouth, and speech delays. As of 2004, most cavities could be fixed without much discomfort by a medical professional and without any serious longterm consequences if the cavities are found and treated early.


Amalgam —A mixture (alloy) of silver and several other metals used by dentists to make fillings for cavities.

Caries —The medical term for tooth decay.

Cavity —A hole or weak spot in the tooth surface caused by decay.

Dentin —The middle layer of a tooth, which makes up most of the tooth's mass.

Enamel —The hard, outermost surface of a tooth.

Fluoride —A chemical compound containing fluorine that is used to treat water or applied directly to teeth to prevent decay.

Mucin —A protein in saliva that combines with sugars in the mouth to form plaque.

Plaque —A sticky, colorless film of bacteria, sugars, and mucin that forms on teeth and causes tooth decay.

Pulp —The soft, innermost layer of a tooth that contains its blood vessels and nerves.

Sealant —A thin plastic substance that is painted over teeth as an anti-cavity measure to seal out food particles and acids produced by bacteria.

Transillumination —A technique of checking for tooth decay by shining a light behind the patient's teeth. Decayed areas show up as spots or shadows.



Mittelman, Jerome, Beverly Mittelman, and Jean Barilla. Healthy Teeth for Kids: A Preventive Program: Prebirth through the Teens. Collingdale, PA: DIANE Publishing, 2004.


"Achievements in Public Health, 1990–1999: Fluoridation of Drinking Water to Prevent Dental Caries." Journal of the American Medical Association 283, no. 10 (March 8, 2000): 1283–86.


American Dental Association. 211 E. Chicago Ave., Chicago, IL 60611. Web site:

American Dental Hygienists' Association. 444 North Michigan Ave., Chicago, IL 60611. Web site:

National Institute of Dental Research. 31 Center Drive, MSC 2190, Building 31, Room 5B49, Bethesda, MD 20892–2190. Web site:

Tish Davidson, A.M.

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