QuickScan Reviews in Pediatric Dentistry, April 30 2009

Background: Many clinicians tell me they are seeing more enamel hypoplasia in permanent first molars these days. Some have speculated as to why this may be occurring, with many differing hypotheses emerging. Recently, others have speculated that the recent increase in the use of certain antibiotics in early childhood could have a mineralization effect on permanent first molars and incisors, which are developing at this time. Several authors have used the phrase "molar incisor hypomineralization" to describe the resultant enamel malformation seen clinically in permanent molars and incisors. Objective: To examine the effect of increased usage of amoxicillin on molar incisor hypomineralization. Participants/Methods: 141 children were ultimately enrolled from a town in Finland; their mean age was 10.7 years. Because the fluoride content of the water in the region of the study was known to be very low, the children in the study had been appropriately supplemented with fluoride since 6 months of age. Lesions with a diameter <2 mm were not included in the findings. For a separate in vitro study, mandibular molar teeth in formative stages were dissected out of mice and placed into a culture medium. Various concentrations of amoxicillin that would correspond to blood levels if used clinically were calculated and placed into different laboratory dishes. Molars were cultured for 10 days, and the effect of the various concentrations of amoxicillin in solution was determined by examination after decalcification and sectioning of the teeth. Results: The clinical results showed that the 141 children, in total, had 529 courses of antibiotics during their first 4 years of life. Only 15% of the children took no antibiotics. During the first year of life, 35% of the children had taken either amoxicillin or penicillin. Molar incisor hypomineralization was seen in 23 children. The number of doses of antibiotics given to the child in the first 4 years of life corresponded to both the presence and severity of molar incisor hypoplasia. Approximately 52% of the children with molar incisor hypomineralization had taken antibiotics during the first year, compared with 34% of the children without the condition. The laboratory results showed that after 10 days in culture, the amoxicillin significantly affected the thickness of enamel formation. The higher the concentration of amoxicillin, the greater the enamel thickness at this early stage of development. Reviewer's Comments: The results of this combined study show that amoxicillin appears to have a profound effect on enamel mineralization and may account for what we are seeing clinically. One should not interpret these early findings to suggest changing antibiotic regimens in childhood, but merely to (at this stage) be aware of the possible relationship shown.