No Evidence to Support the Claim that Amoxicillin Causes Molar-Incisor Hypomineralization

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All children (n = 217) attending the second to fifth years of comprehensive schools in the nonfluoridated town of Lammi, Finland, were invited to participate in the study. Of those invited, 147 (67.7%) agreed to participate and study data were obtained for 141. The children ranged in age from 7.8 to 12.7 years with a mean of 10.7 years. Slightly more than half (53.9%) of the children were male. No other information was presented. The key study factor was antibiotic use during the first, second, third, and fourth years of life. Information on amoxicillin, penicillin V, cephalosporin, macrolides (erythromycin), sulfonamide, and trimethoprim use was obtained from the local health center medical records. The outcome measure was hypomineralization of the permanent first molars. A tooth was considered to be hypomineralized if it had a demarcated opacity, broken-down hypomineralized enamel, or an atypical restoration. Lesions smaller than 2 mm in diameter were excluded. The potential issue of missing first molars and how they should be classified was not addressed. Eighty-five percent of the children had received at least one course of antibiotics. During the first year of life, 34.8% had taken either penicillin or amoxicillin or both, whereas 5.0% received erythromycin. Twenty-three children (16.3%) had one or more permanent first molars with hypo-mineralization. Of the children with molar hypomineralization (MH), 12 (52.2%) had taken antibiotics during the first year of life compared with 33.9% of the children without MH (P > .05). The unadjusted odds ratio (OR) for MH among children who received amoxicillin during the first year was 2.06 (95% confidence interval [CI] 1.01-4.17), whereas the unadjusted OR for MH was 4.14 (95% CI, 1.05-16.4) among children who received erythromycin during the first year. The authors concluded that the early use of amoxicillin is among the causative factors of molar hypomineralization. STUDY 2 SUMMARY SUBJECTS: Mandibular molar explants from 27 mouse embryos in an organ culture. Exposure to amoxicillin at 100 mg/mL, 1 mg/mL, and 4 mg/mL. Enamel and dentin thickness after 10 days of culture. In first molars with enamel, the enamel-dentin layer was thicker in explants exposed to amoxicillin at concentrations of 1 mg/mL or more compared with controls and those exposed to 100 mg/mL (P < .001). The enamel/dentin ratio also differed significantly (P < .007). The actual thickness data were not presented. The authors concluded that the early use of amoxicillin is among the causative factors of molar hypomineralization.