Dental sealants are thin, protective coatings applied to the chewing surfaces of the back teeth (molars and premolars) to prevent decay. These teeth have deep grooves where food particles and bacteria can easily get trapped, making them highly susceptible to cavities. While sealants are a common and effective preventive measure, public concern often arises regarding the materials used in their composition. This concern centers on the potential for chemical exposure, which requires a closer look at the scientific evidence.
Composition of Dental Sealants
Most dental sealants are resin-based materials, specialized plastics designed to bond tightly to tooth enamel. Their core structure uses large molecules called monomers, which link together (polymerize) to form a hard, protective barrier when cured by a light source. The most common monomer is Bisphenol A-glycidyl methacrylate (Bis-GMA), which provides strength and durability. Other monomers, such as UDMA and TEGDMA, are often combined with Bis-GMA to adjust the material’s properties. Fillers, like small particles of glass, are frequently added to enhance wear resistance.
Addressing Concerns About BPA and Its Derivatives
BPA Release Mechanism
The primary chemical concern is potential exposure to Bisphenol A (BPA), a compound categorized as a potential endocrine disruptor. BPA is not typically an intentional ingredient in modern dental sealants. However, the issue arises because Bis-GMA and Bisphenol A dimethacrylate (Bis-DMA) are chemically related to BPA. Trace amounts of BPA can appear as a minor byproduct or through the breakdown of these derivatives by salivary enzymes in the mouth.
Exposure Levels and Duration
The release of unreacted monomers, including trace BPA, occurs most significantly immediately after the sealant is placed and cured. This leaching is a short-term event; the highest concentration of BPA is detectable for only a few hours and typically becomes undetectable after 24 hours. The amount of BPA released is extremely low; for instance, applying four dental sealants releases an average of only 0.09 nanograms of BPA. This minimal, temporary exposure is significantly lower than the daily exposure an individual receives from common environmental sources, such as food packaging.
Official Health Organization Safety Stance
Major public health organizations have consistently reviewed the data on dental sealants and chemical exposure, concluding that the treatment is safe and highly beneficial. The American Dental Association (ADA) Council on Scientific Affairs states there is no scientific basis for health concerns related to BPA exposure from any dental material. This determination is based on the extremely small quantity and brief duration of potential exposure. Regulatory bodies like the U.S. Food and Drug Administration (FDA) have established safe exposure levels for BPA that are vastly higher than the amounts released by sealants. The consensus among the ADA and the Centers for Disease Control and Prevention (CDC) is that the substantial preventive benefits of sealants, which can reduce the chances of new decay by up to 70%, far outweigh the minimal, theoretical risk.
Steps to Minimize Potential Exposure
Clinicians employ specific techniques to reduce a patient’s already minimal exposure to unreacted monomers and trace BPA. The most effective method involves removing the oxygen-inhibited layer, a thin, uncured film that forms on the sealant surface during curing. This layer contains the residual monomers. Immediately after curing, the dental professional polishes the surface using a mild abrasive, eliminating between 93% and 95% of the residual monomers. Following polishing, patients are instructed to thoroughly rinse their mouth with water for about 30 seconds, further decreasing any remaining salivary BPA levels.