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Do Dental Night Guards Contain Chemicals of Concern?


RAPID RESPONSE QUESTION: Following the advice of our 2009 Rapid Response, a consumer asked his dentist about the presence of chemicals of concern in materials for a new custom dental night guard (or appliance).

Request by: Anonymous Consumer

Key Findings

  • Some current dental guard products contain phthalates, BPA or other chemicals of concern.
  • Dentists often do not have information on the chemicals used in products they purchase for patients.
  • Data provided by a dental laboratory listed dialkyl phthalate in the materials used to make the guard.
  • Suppliers may offer technical data, such as Material Safety Data Sheets, but these won’t necessarily contain the full list of ingredients used in a product.

Background

PPRC occasionally receives inquiries on the safety of specific products. A recent inquiry on the safety of chemicals in night guard materials was prompted by our 2009 Rapid Response “Safety of Plastics in Dental Appliances.” This consumer was concerned about bisphenol-a (BPA) and wanted help understanding chemical information provided by his dentist.

In common practice, a dentist only makes a mold of the patient’s teeth. Using the mold, a separate dental laboratory prepares the custom appliance for the dentist. In this case, the dentist requested information from the appliance maker (the offsite laboratory), who complied by forwarding a Material Safety Data Sheet (MSDS) from the material/ chemical supplier, Henry Schein, Inc. MSDSs for various products are available at the Henry Schein, Inc. website.

As required, the Schein MSDS for “Easy Flow Acrylic Powder” listed three hazardous ingredients: Dialkyl Phthalate (CAS# 84-66-2), Titanium Dioxide (CAS# 13453-67-7), and Mineral Pigments (CAS# 57453-37-5), but made no mention of BPA, the chemical of concern to the consumer.

Limitations of Material Data Safety Sheets

Unfortunately, MSDSs are not designed to convey chemical safety information to consumers, but rather to inform workers in occupational settings. Chemicals or mixtures are typically identified by CAS numbers (CAS#), which are often used as an identifying index in chemical information databases. MSDS sheets are only required to list hazardous ingredients, so they won’t necessarily include chemicals of concern which are not yet regulated by OSHA. Furthermore, there is no requirement to list hazardous ingredients present at less than 1% (less than 0.1% for carcinogens), so ingredients could be missing from an MSDS, but still present in the product.

While many dental polymers may use BPA as an ingredient, most polymers are not considered hazardous. New polymer materials are also mostly exempt from the Toxic Substances Control Act, due to a presumption of safety. Roughly speaking, because the size of the polymer molecule prevents their absorption by the bodies systems, they are assumed to be essentially inert. Health concerns are sometimes associated with the monomers (the small molecules that are put together to make the polymer and which remain at some level in all polymers) and additives or contaminants.

In this case, the MSDS product name suggests use of acrylic plastics (acrylates), but they are otherwise not specifically listed as ingredients. There are many types of acrylates, some of which incorporate bisphenol A (BPA) and similar chemicals. While bisphenol A is currently under scrutiny by federal agencies, it is not currently listed as hazardous under US regulation, and would not generally be listed on an MSDS. Information on BPA content may be listed on some manufacturer material brochures or websites, but most likely consumers will need to contact supplier technical staff directly. In this case, Henry Schein, Inc., a very large company, likely has staff available to respond to consumer inquiries.

Easy Flow Hazardous Chemicals

As mentioned above, the Easy Flow Acrylic Powder MSDS lists three hazardous ingredients, Dialkyl Phthalate (CAS# 84-66-2), Titanium Dioxide (CAS# 13453-67-7), and Mineral Pigments (CAS# 57453-37-5). Dialkyl phthalate, also called diethyl phthalate, has been listed as a potential endocrine disruptor by TEDX (The Endocrine Disruptor Exchange). Chemicals of concern are listed on the TEDX website via a downloadable Excel spreadsheet indexed by CAS number. Washington State has also identified diethyl phthalate on its list of “Chemicals of High Concern to Children,” due to the potential for endocrine effects. There are varying opinions about whether diethyl phthalate is a risk for adults in this or other applications, but those most concerned about safety might choose to avoid these products if there are BPA- and phthalate-free alternatives available.

Two standard databases of chemical information that we typically use, eChemPortal and the Hazardous Substances Data Bank (HSDB) had no information for the CAS numbers provided by Henry Schein, Inc. for either titanium dioxide or the mineral pigments. Searching the database for materials similar to titanium dioxide might reveal some relevant safety information, but given the potentially significant risk from phthalates, no further analysis was pursued.

Conclusions

Without further information from the supplier, it is not possible to determine whether the products in question contain BPA. As described in the 2009 Rapid Response, there is reason for concern about BPA in dental products, but no black and white answer regarding health effects of chemicals in dental applications.

The MSDS lists hazardous chemicals, but no information could be identified using the CAS numbers provided for two of the specific chemicals. On the other hand, dialkyl phthalate has been identified as a potential endocrine disruptor. Those concerned about phthalate exposure should inquire about the availability of phthalate-free alternative dental materials.

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