Use of the antibiotic amoxicillin during infancy appears to be linked to tooth enamel defects in permanent teeth

Use of the antibiotic amoxicillin during infancy appears to be linked to tooth enamel defects in permanent teeth, according to a study in the October issue of Archives of Pediatrics and Adolescent Medicine.

Dental fluorosis, a result of exposure to excessive fluoride during enamel formation, is one of the most common developmental enamel defects, according to background information in the article. The clinical signs range from barely noticeable white flecks, to pits and brown stains. Amoxicillin is one of the most common antibiotics used among pediatric patients, mainly for treatment of otitis media--infection and inflammation of the middle ear. There has been some evidence that amoxicillin use could be associated with dental enamel defects, and, the authors suggest, even a small effect on dental enamel could have a significant effect on the public's dental health because of the widespread use of amoxicillin.

Liang Hong, D.D.S., M.S., Ph.D., of the University of Iowa, Iowa City, and colleagues assessed the association between dental fluorosis and amoxicillin use during early childhood. (Dr. Hong is now with the Department of Dental Public Health and Behavioral Science, University of Missouri - Kansas City.) The researchers analyzed data from the Iowa Fluoride Study, a prospective study investigating fluoride exposures, biological and behavioral factors, and children's dental health. They followed 579 participants from birth to 32 months, using questionnaires every three to four months to gather information on fluoride intake and amoxicillin use.

"The results show that amoxicillin use during early infancy seems to be linked to dental fluorosis on both permanent first molars and maxillary central incisors," the authors report. "Duration of amoxicillin use was related to the number of early-erupting permanent teeth with fluorosis."

By the age of one year, three-quarters of the subjects had used amoxicillin. By 32 months, 91 percent of participants had used amoxicillin. "Overall, 24 percent had fluorosis on both maxillary central incisors," the authors write.

Amoxicillin use from three to six months doubled the risk of dental fluorosis. "The significantly elevated risk for dental fluorosis associated with amoxicillin use during early infancy was found at all levels of statistical analyses, even after controlling for other potential risk factors, such as fluoride intake, otitis media infections, and breastfeeding," the authors report.

The authors emphasize that additional laboratory and clinical studies--including controlled animal studies with specified amoxicillin dosages, chemical analysis and histological examination of affected teeth, and additional well-designed epidemiological studies--are needed to confirm the results.

"The findings suggest that amoxicillin use in infancy could carry some heretofore undocumented risk to the developing teeth," they conclude. "While the results of this one study do not warrant recommendations to cease use of amoxicillin early in life, they do further highlight the need to use antibiotics judiciously, particularly during infancy."