Indeed, a review study last fall by the Cochrane Collaboration, a group that evaluates medical research, found that 5- to 10-year-olds who used sealants had less than half the decay on biting surfaces five years after treatment than those who brushed regularly.But are they safe? Hermetically sealing a tooth may sound odd, if not unnecessary, but what has concerned researchers through the years is that dental sealants can contain the same chemicals that caused controversy when present in plastic baby bottles: bisphenol-A (BPA) or its chemical cousin, bisphenol-A dimethacrylate (BPA-DMA). Though still investigating, the FDA currently deems these compounds safe, but some researchers have impugned them in everything from diabetes, cancer and - most alarming for children - to accelerating the onset of puberty due to estrogen-like effects.