Association of amoxicillin use during early childhood with developmental tooth enamel defects.

BACKGROUND It has been speculated that amoxicillin use could be associated with dental enamel defects. OBJECTIVE To assess the association between dental fluorosis, one of the most common developmental tooth enamel defects, and amoxicillin use during early childhood. DESIGN, SETTING, AND PARTICIPANTS As participants in the Iowa Fluoride Study, subjects were followed up from birth to 32 months using questionnaires every 3 to 4 months to gather information on fluoride intake and amoxicillin use. METHODS Early-erupting permanent teeth of 579 subjects were assessed for fluorosis using the Fluorosis Risk Index at approximately the age of 9 years. Relationships between fluorosis and amoxicillin use were assessed using relative risk (RR), Mantel-Haenszel stratified analyses, and multivariable logistic regression. RESULTS Amoxicillin use was reported by 75% of subjects by 12 months and 91% by 32 months. Overall, 24% had fluorosis on both maxillary central incisors. Amoxicillin use from 3 to 6 months significantly increased the risk of fluorosis on the maxillary central incisors (RR = 2.04; 95% confidence interval [CI], 1.49-2.78). After adjusting for fluoride intake and otitis media, the risk of fluorosis on the maxillary central incisors from amoxicillin use during 3 to 6 months (Mantel-Haenszel RR = 1.85; 95% CI, 1.20-2.78) was still statistically significant. Multivariable logistic regression analyses confirmed the increased risk of fluorosis from amoxicillin use during 3 to 6 months (odds ratio = 2.50; 95% CI, 1.21-5.15); fluoride intake was also statistically significant. CONCLUSION The findings from this study suggest a link between amoxicillin use during infancy and developmental enamel defects of permanent teeth; however, further research is needed.