The most common dental complication of eating disorders derives from repeated self-induced vomiting. Gastric (stomach) acid that accompanies undigested foods travels up the esophagus into the mouth and gradually erodes dental enamel (the external, protective coating of a tooth), leaving the dentin and other interior parts increasingly vulnerable to damage. Although enamel break-down frequently manifests on the inside of the front teeth, it can also affect the back teeth, causing metal fillings to look unusually elevated. As enamel deteriorates, teeth grow softer, rounder, and increasingly sensitive to touch and temperature. Dentin hypersensitivity, which is typically experienced as a brief, sharp pain, can impact a patient's eating behavior and oral hygiene. Dental erosion ranges from mild to severe but tends to be most pronounced in chronically ill individuals who frequently induce vomiting.

Dental professionals advise against brushing immediately after vomiting because doing so can promote enamel erosion. Instead, they often suggest rinsing with sodium bicarbonate to neutralize the digestive acids in the mouth. Fluoride, which helps strengthen tooth enamel, may be applied to the teeth in the dentist’s office or recommended to the patient in the form of an over-the-counter rinse. A number of individuals with substantial erosion and caries need restorative work, such as crowns (durable coverings, or “caps”) or resin-based composite (tooth-colored) fillings.

Malnutrition, dehydration, dry mouth and poor dental hygiene can increase the risk of cavities. Another danger is the high intake of sugars and other carbohydrates associated with binge eating. Fluoride applied to teeth very early in life is a potential protective measure. And genes play a role in determining degree of vulnerability to cavities. Due to a combination of all these influences, cavity rate varies considerably among individuals with eating disorders.

Enamel erosion and possible cavities are not the only oral signs of eating disorders. Others include the following: swollen, red gums (gingivitis); reddened, sore throat; dry cracked lips and corners of the mouth; and enlarged salivary glands.

When a person with anorexia nervosa, bulimia nervosa or EDNOS visits the dentist—either for a routine check-up or for help with a symptom—she does not necessarily disclose information about her abnormal eating behaviors. Ashamed of her disorder or unable to admit that she has one, she may have been suffering for months or years without confiding in any health professional. By noticing enamel erosion or other findings as a sign of an underlying eating disorder, the dentist often plays an important role in detecting the illness and in referring patients for medical and psychological evaluation. Some individuals may be more comfortable sharing information about their eating disorder with the dental hygienist first, before discussing it with the dentist. If the individual is over 18 years of age, her dental visit is strictly confidential; if she is younger, however, information, including findings suggestive of an eating disorder, is usually given to her parents.

A dentist communicates with the other members of the patient’s professional treatment team, which generally consists of a primary care physician, a psychotherapist, a registered dietician, and perhaps a psychopharmacologist. In addition, the dental professional will often help educate the individual with an eating disorder, gently explaining the potential oral complications of the illness, encouraging diligent home hygiene, offering empathy and supporting recovery.