Plastic mouthguards, whether used for sports protection, teeth grinding (bruxism), or jaw clenching, are designed for prolonged contact with the sensitive tissues of the mouth. The convenience and affordability of these plastic devices have made them commonplace for millions of users. However, a significant concern is the potential for these materials to transfer chemical components into the body, raising questions about long-term safety. While modern manufacturing standards aim for biocompatibility, the chemical composition of certain plastics and the conditions of their use can introduce a risk of chemical exposure. This concern centers on specific compounds within the plastic matrix migrating into the oral environment.
Understanding Chemical Components in Mouthguards
The majority of plastic mouthguards are manufactured from a few primary materials, each carrying a different chemical profile and potential for risk. Ethylene-vinyl acetate (EVA) is a common thermoplastic, valued for its flexibility and shock absorption, and is widely considered safe, especially when medical-grade versions are used. Conversely, some less expensive stock mouthguards may utilize polyvinyl chloride (PVC), which requires plasticizers to achieve the necessary flexibility. Harder, custom-made night guards often incorporate acrylic resins, which are durable but can contain residual unreacted chemical components.
A major category of concerning chemicals includes Bisphenols, such as Bisphenol A (BPA) and its substitute, Bisphenol S (BPS). These compounds are known endocrine disruptors, meaning they can interfere with the body’s hormonal systems. Phthalates are another group of chemicals often added to plastics to increase their pliability and softness. Both Bisphenols and Phthalates are concerning because their leaching from the material has been associated with potential reproductive and developmental harm.
Residual monomers, like methyl methacrylate (MMA), are a source of potential toxicity, particularly in mouthguards made from acrylic resins. If the material is not fully cured during manufacturing, traces of this chemical can remain and leach out into the saliva. Exposure to residual MMA is known to cause localized irritation, allergic reactions, and inflammation of the gums. Finally, the physical breakdown of the plastic over time can release microplastics, which are tiny fragments raising additional questions about long-term exposure.
Factors That Increase Chemical Migration
The migration of chemical components from a mouthguard is highly dependent on environmental factors and material degradation. Temperature plays a significant role, particularly during the initial fitting process for “boil-and-bite” mouthguards. The high heat used to soften the thermoplastic material accelerates the release of volatile organic compounds and other embedded chemicals. Repeated exposure to high temperatures, such as attempting to sanitize a mouthguard with boiling water, compromises the plastic’s structural integrity and increases the potential for chemical release.
Physical stresses placed on the mouthguard during use also accelerate chemical leaching. Constant chewing, clenching, and grinding cause mechanical wear and tear, creating microscopic fractures and surface abrasions. This damage significantly increases the surface area exposed to saliva, accelerating the rate at which residual chemicals or microplastic particles escape the matrix. Even professional thermoforming techniques can cause the material to stretch and thin, potentially compromising the material’s barrier properties.
The unique chemical environment of the mouth contributes to the breakdown of the polymer material. Saliva facilitates hydrolysis, where water molecules break down the chemical bonds in the plastic. Changes in the oral pH level can significantly affect this degradation. An acidic environment, caused by certain foods, drinks, or oral bacteria, accelerates the degradation of acrylic resins and increases the rate of residual monomer leaching.
Choosing and Maintaining Safer Materials
Consumers concerned about chemical exposure should start with careful material selection. Seek products explicitly labeled as “BPA-free” and “Phthalate-free,” which indicates the manufacturer has substituted these chemicals with alternatives. Medical-grade plastics, such as specific formulations of EVA and copolyester, are generally safer because they are subjected to rigorous testing for long-term oral contact. High-performance thermoplastics and medical-grade silicones are also options that minimize the risk of chemical migration.
Opting for a custom-fitted mouthguard made by a dental professional provides a safety advantage over generic store-bought options. These devices are fabricated using high-quality, fully cured materials in a controlled laboratory setting, minimizing the presence of residual monomers like MMA. Professional fitting ensures the guard is a precise thickness and shape, which prevents the user from excessively chewing or grinding on the material. For individuals with known sensitivities, hypoallergenic materials, including medical-grade silicones, can help avoid allergic reactions.
Proper maintenance minimizes the potential for chemical leaching and preserves material integrity. After each use, the mouthguard should be thoroughly cleaned by rinsing it with cool water and gently brushing it with a mild cleanser. This daily cleaning prevents the buildup of bacteria and biofilm, which contributes to the acidic environment that accelerates polymer breakdown. Storing the mouthguard in a ventilated case allows it to dry completely, discouraging microbial growth and ensuring the material remains stable.