Tooth enamel abnormality in children, molar incisor hypomineralization (MIH), may result from exposure to the industrial chemical bisphenol A (BPA), authors of a new study conclude after finding similar damage to the dental enamel of rats that received BPA.
Many enamel abnormalities may be used as an early sign of exposure to bisphenol A (BPA) and some other similar endocrine disruptors.
BPA is an endocrine disruptor, or hormone-altering chemical, that has been linked to numerous adverse health effects in humans. It appears in many plastic and resin household products and food containers, including until recently baby bottles, sippy cups and infant formula packages.
Molar incisor hypomineralization (MIH) describes the clinical picture of hypomineralization of systemic origin affecting one or more first permanent molars (FPMs) that are associated frequently with affected incisors. MIH causes white or brown opaque spots on an affected child's permanent first molars and incisors (the middle four teeth on the top and bottom), which become sensitive, painful and prone to cavities. Recent published data show that MIH affects up to 18 percent of children ages 6 to 9 years. MIH molars are fragile and caries can develop very easily in those molars. Although MIH molars are well known by paediatric dentists and their occurrence is related in severe cases to major clinical problems, only limited data of the size of the problem are available. The prevalence of MIH ranges in the literature from about 3.6 to 25% and seems to differ in certain regions and birth cohorts. Unfortunately more complete comparable valid data are lacking at the moment. It seems that several aetiological factors can cause the enamel defects and that their occurrence is child related. Although the cause is unclear, it appears to have an environmental origin, according to the study authors.
In the first part of the study, Sylvie Babajko, PhD, a researcher at the French National Institute of Health and Medical Research (INSERM) in Paris, and her colleagues gave rats low doses of BPA, comparable to exposure in humans. The rats received BPA from fetal life to 30 days after birth. She said BPA caused enamel defects similar to MIH in humans, especially in male rats.
"Our study shows, for the first time, that BPA affects dental cells, and subsequently enamel synthesis, " Babajko said.
Babajko reported that an increase in estrogen activity had a greater effect on the tooth enamel in male rats than in female rats. This finding, she said, suggests possible sexual differences in enamel quality.