| It has been speculated that amoxicillin use could be associated with developmental enamel defects. This study assessed the association between dental fluorosis and amoxicillin use during early childhood on both primary teeth and early erupting permanent teeth. As part of the Iowa Fluoride Study, subjects were followed prospectively from birth to 32 months with questionnaires every 3--4 months to gather information on fluoride intake and amoxicillin use. Subjects (n = 490) were assessed for primary tooth fluorosis at approximately age five by calibrated examiners using the Tooth Surface Index of Fluorosis (TSIF). Amoxicillin use from 6 weeks to 6 months significantly increased the risk for fluorosis on primary second molars in bivariate analyses. After controlling for fluoride intake, the adjusted risks of fluorosis were not significant for amoxicillin use on primary second molars. Subjects (n = 453) were assessed for dental fluorosis on early-erupting permanent teeth using the Fluorosis Risk Index (FRI) at approximately age nine. Amoxicillin use during early infancy significantly increased the risk of dental fluorosis on both permanent maxillary central incisors and first molars. These significant, increased risks were consistently found at all levels of the analyses. For maxillary central incisors, the relative risk for amoxicillin use during 3 to 6 months was 1.94 (95%CI 1.49--2.56, p < 0.0001) in bivariate analyses and 1.92 (95%CI 1.32--2.78, p = 0.001) after controlling for fluoride intake and otitis media. For permanent first molars, the relative risk for amoxicillin use during birth to 6 months was 1.94 (95%CI 1.30--2.86, p = 0.0009) in bivariate analyses and 1.92 (95%CI 1.27--2.94, p = 0.006) after controlling for fluoride intake and otitis media. The analyses suggested no significant two-way interactions among amoxicillin use, fluoride intake, and otitis media. This indicated that the effects from amoxicillin use on dental fluorosis are largely independent of other risk factors. The study also confirmed the importance of chronic excessive fluoride ingestion on dental fluorosis. However, the data do not implicate any other class of antibiotics. Amoxicillin use during early infancy appears to be an important factor in the etiology of dental fluorosis, but further research is needed. |
