A mouth guard is a device that protects a person’s teeth and mouth from damage during certain activities that may cause dental harm. More than 200,000 mouth and jaw injuries are reported each year, according to the Academy of General Dentistry.

Mouth guards are flexible devices made of plastic that cover the teeth. Mouth guards are typically worn to protect teeth during activities that leave the teeth vulnerable to injury. People wear them when playing a wide variety of sports, including football, hockey, boxing, basketball, baseball, soccer, gymnastics, volleyball, wrestling, lacrosse and rugby.

Although people usually think of contact sports as causing most dental injuries, nearly half of oral injuries in children occur during participation in baseball and basketball, according to the American Academy of Pediatric Dentistry.

Mouth guards are also used during activities such as biking, in-line skating, skateboarding and martial arts. Removable appliances (e.g., retainers, bridges or complete or partial dentures) should not be worn with mouth guards during participation in athletic activity. Any mouth jewelry, especially “barbells” in the tongues of people with oral piercings, should not be worn at the same time as a mouth guard. This can cause gagging due to excess saliva production, choking or intestinal injury if the jewelry is accidentally swallowed.

In addition, mouth guards are sometimes recommended or prescribed by a dentist for patients who excessively grind their teeth (bruxism). This can prevent conditions such as jaw pain and excessive wear of the teeth. Mouth guards may also be used to help treat TMJ disorder.

In most cases, people wear mouth guards that cover the top teeth only. However, people with braces or other fixed appliances (e.g., bridges) on the lower jaw may benefit from having a mouth guard that covers the lower teeth as well. People who wear mouth guards that fit properly are able to breathe normally and talk with only a minor obstruction to speech.

There are three different types of mouth guards. Stock mouth guards are inexpensive and come preformed. However, they usually do not fit well and may make it difficult for the wearer to breathe and talk. Most experts do not consider that stock mouth guards provide as much protection as other types of mouth guards, although they may be the only type available for some patients, such as those who wear braces.

Boil-and-bite mouth guards are relatively inexpensive and may be found in sporting goods stores. They usually are made of acrylic gel or thermoplastic materials and fit better than stock mouth guards because the wearer dips the mouth guard into a pot of boiled water before fitting it around the teeth. The heat of the water leaves the plastic pliable so that it fits around the teeth. However, the directions must be followed carefully to ensure a proper fit. Patients in the middle of orthodontic treatment, such as braces or removable aligners, should not wear these fitted mouth guards.

Custom-fitted mouth guards are made by a dentist and are designed to precisely accommodate an individual’s bite. A cast of the patient’s teeth is used to create this type of mouth guard. Custom-fitted mouth guards are typically used for patients who are diagnosed with bruxism.

The better a mouth guard fits, the more likely it is to be comfortable, tear-resistant and resilient. Mouth guards that fit properly also are more likely to evenly distribute the force of an impact that results from an accident or collision. In addition, patients are more likely to wear mouth guards that fit properly than those that do not.

Mouth guards can be an extremely effective device in protecting a patient’s teeth and mouth. However, a mouth guard must be worn regularly for a person to get the maximum protective benefit from it. Some people refuse to wear mouth guards because of concerns over cost or image. Others may dislike the inconvenience of wearing a mouth guard. Nonetheless, experts continue to promote mouth guard use as crucial to preventing potentially devastating oral injuries.