Today there are more than 10 million American children receive fillings every year. However, according to the new study in the journal Pediatrics, a common composite formula may be placing kids at slightly higher risk for anxiety and depression.

Composite fillings are typically made of glass or quartz mixed with resins and adhesives. But these materials, while approved by the FDA, have not been studied for long-term health effects.

The study which was funded by the National Institutes of Health, stated children with a popular composite filling known as bisphenol-A-glycidyl-methacrylate (Bis-GMA) displayed worse scores on scales of “psychosocial” well-being up to five years after treatment, compared to kids who received silver amalgam fillings or a composite made with different materials. Children exposed to the most Bis-GMA fillings for the longest periods of time were two to four times more likely to report “at risk” psychological problems requiring medical help. The association was strongest for kids with cavities filled in the back molars, where the composite can break down and possibly enter the bloodstream.