Why do dentists need to use a dental dam?

Dental dams isolate teeth and clear the field -- or the area being worked on -- of excess moisture. Most often dams are used for endodontic procedures, such as root canals or other interior and below-tooth work because controlling the amount of saliva on the exposed area reduces some of the bacteria that can get inside and cause infection and/or irritation. Dams also keep instruments and pieces of composite material of the tooth itself from going down the oral cavity and into the body.

Additionally, when the mouth, lips and tongue are covered by a dam, there is less likelihood that sharp tools can nick tissue and lead to bleeding or blood and saliva sprays that can endanger dental professionals if a patient has an infectious disease. Some professionals also use dams for non-endodontic and minor procedures such as replacing fillings, making molds of teeth or even whitening teeth, for example, simply to protect the patient from swallowing debris or to keep teeth as dry as possible for receiving overlays and coatings.

Both dental assistants and dentists must show proficiency in fitting and removing dental dams, but some studies find that, in practice, many dental professionals don't use them. Reports published by the National Institutes of Health (NIH) in the U.S. showed that between 53 and 63 percent of dentists surveyed didn't use dental dams at all. Their reasons for not using them ranged from inconvenience and irrelevance to their procedures to patients refusing to wear them, among others [sources: ADA; Gilbert; Hill]. Combined, these surveys included less than 1,000 practicing respondents, but if representative of dentistry as a whole, does it even matter if dental dams are used?

According to the Centers for Disease Control and Prevention (CDC) and the American Association of Endodontists (AAE), it does matter. Dental dams are effective in limiting the spread of bacteria into the area of the mouth that is exposed during procedures and in keeping the same bacteria from being swallowed or taken in internally. These rubber sheets also serve to protect dentists, hygienists and patients from possible exposure to HIV, hepatitis and other infectious diseases or blood-borne pathogens during procedures.

Using a dental dam is mandatory for certain endodontic procedures in the United States, and according to the AAE it should be the required standard of care. It is a recommended "universal precaution" in CDC statements on infection in dental care practice. Additionally, it adds protection for dentists by decreasing liability if a patient swallows or chokes on something during treatment [sources: AAE; CDC].

How do patients take to dental dams and can they choose whether or not to, ahem, dam it?

Having a sheet of rubber blocking your airway can take some getting used to, but for most people who can breathe through their noses, it isn't too uncomfortable. Those with conditions inhibiting nose-breathing, considered mouth-breathers in medical terms, may have considerable discomfort if fitted with a dental dam. Because a dam is attached either by special clamps, with adhesive or with some twining of dental floss over teeth -- similar to tying a boat line to a post on a dock or securing a tent by stretching it across stakes -- dentists and hygienists can fit the barrier tightly, preventing much exchange between the mouth cavity and the area being worked. Small holes are punched into the dam to match the opening size and placement of teeth needing exposure, but other than those cuts, the dam seals off the rest of the mouth [source: Perrine].

Some may find this setup claustrophobic, and there may be some gagging or difficulty breathing, but generally it is not a problem or major source of discomfort for patients. Precautions do need to be taken for those patients with latex allergies, but non-latex varieties of dental dams are available. Patients can refuse to wear dams with or without medical reasons such as mouth-breathing issues or fears of dental procedures.

Although some studies suggest that many dentists are foregoing the use of dental dams, most professional associations, including the American Dental Association (ADA), advocate their use and make a point of including them in training dental professionals. When used for root canals, for instance, not only do dental dams keep the open root area dry and better exposed so the dentist can focus on the work, they also keep bacteria and saliva away from an area where infection is being cleaned and where it needs to remain clean before closing up the tooth.

After opening wide and getting a dental diagnosis, it doesn't hurt to ask your dental care provider about when and if a dam will improve the quality of care and finished work and whether it's considered mandatory for the procedure.

More information and links on oral care and dental dams follows.