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.

Dr Liang Hong, of the University of Iowa, Iowa City, Chicago, and colleagues assessed the association between dental fluorosis and amoxicillin use during early childhood.

The researchers analysed data from the Iowa Fluoride Study, a prospective study investigating fluoride exposures, biological and behavioural 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 showed that amoxicillin use during early infancy seemed to be linked to dental fluorosis on both permanent first molars and maxillary central incisors. The 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 and by 32 months, this had risen to 91% of participants. The study found that overall, 24% had fluorosis on both maxillary central incisors and that 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 reported.

“The findings suggest that amoxicillin use in infancy could carry some undocumented risk to the developing teeth,” the authors concluded. “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.”