Mouthguard materials by nature must have shock absorption qualities. They must be resilient and yet soft enough to absorb impact energy and reduce transmitted forces. The thickness of mouthguard material is directly related to energy absorption and inversely related to transmitted forces when impacted. However, wearer comfort is also an important factor in their use. Thicker mouthguards are often not user-friendly. Transmitted forces through different thicknesses of the most commonly-used mouthguard material (ethylene vinyl acetate – EVA – Shore Hardness of 80) were compared when impacted with identical forces capable of damaging the oro-facial complex. The results showed that the optimal thickness for EVA mouthguard material with a Shore Hardness of 80 is around 4 mm. on the occlusal surface. All teeth must be properly covered and the bite balanced accordingly. Increased thickness, while improving performance marginally, may result in less wearer comfort and acceptance.

Stenger, in 1964, reported that forces from mandibular impact would be attenuated with a mouthguard, resulting in fewer injuries. Hickey discussed that mouth protectors reduced pressure changes and bone deformation within the skull in a cadaver model. He demonstrated a decrease of 50% in the amplitude of the intracranial pressure after a blow to the chin when wearing a mouthguard.

Dr. Karen Johnston, a prominent Canadian concussion researcher, noted that: “The force required to concuss a fixed head is almost twice that required to concuss a mobile head”. Further, there is some correlation between the degree of rotation that the head goes through on impact and the severity of the concussion that might result.

By activating additional head and neck muscles at the time of impact this arc of rotation might be decreased, leading to less harmful movement of the brain inside the skull. Some researchers have begun to show that by being able to clench down harder on a mouthguard the activation of the head and neck muscles might serve to stabilize the head. Some have suggested further that this effect might be in place whether or not the athlete sees the impact coming.

The stock mouthguard, available at most sporting good stores, come in limited sizes (usually small, medium, and large) and are the least expensive and least protective. The prices range approximately from, $3 to $25. These protectors are ready to be used without any further preparation; simply remove from the package and immediately place in the mouth. They are bulky and lack any retention, and therefore must be held in place by constantly biting down. This interferes with speech and breathing, making the stock mouthguard the least acceptable and least protective. This type of mouthguard is often altered and cut by the athlete in an attempt to make it more comfortable, further reducing the protective properties of the mouthguard. It has been suggested and advised in the medical/dental literature that these types of mouthguards not be worn due to their lack of retention and protective properties.

As sports dentists and health professionals interested in injury prevention, we do not recommend this type of mouthguard to our patients and athletic teams. See photo of Stock Mouthguard after use for several weeks.

Presently, this is the most commonly used mouthguard on the market. Most marketing and advertising in the past has been for this type mouthguard. Made from thermoplastic material, they are immersed in boiling water and formed in the mouth by using finger, tongue, and biting pressure. Available in limited sizes, these mouthguards often lack proper extensions and repeatedly do not cover all the posterior teeth. Dental mouth arch length studies have shown that most boil and bite mouthguards do not cover all posterior teeth in a majority of high school and collegiate athletes. Athletes also cut and alter these bulky and ill fitting boil and bite mouthguards due to their poor fit, poor retention, and gagging effects. This in turn further reduces the protective properties of these mouthguards. When the athlete cuts the posterior borders or bites through the mouthguard during forming, the athlete increases their chance of injury, especially concussion, from a blow to the chin. Some of these injuries, such as concussion, can cause life long effects. (See concussion section of Sports Dentistry On Line). Certain thicknesses and extensions are necessary for proper mouthguard protection.

Dr. Keith Hunter, Australian sports dentist, reported that mouthguards should be of certain thickness, without being bulky. He suggests a thickness of 3mm. It should be noted that each athlete should be evaluated individually for thickness and design as to promote comfort and sufficient protection.
Joon Park, PhD et al, at the First International Symposium on Biomaterials in August of 1993 reported that boil & bite mouthguards provide a false sense of protection due to the dramatic decrease in thickness occlusally during the molding and fabrication process. Dr. Park further stated that “Unless dramatic improvements are made, they (boil and bite mouthguards) should NOT be promoted to patients as they are now.”

Care should be taken by the public when bombarded with clever marketing schemes, claims, and promotions by stock and boil and bite mouthguard companies. The bottom line is that Stock and Boil and Bite Mouthguards do not provide the expected care and injury prevention that a properly diagnosed and fabricated custom made mouthguard does. Why is there a general belief that mouthguards are uncomfortable, do not fit, are bulky, and interfere with breathing and speaking? Could it be because 90% of today’s mouthguards worn are of the stock or boil and bite variety, and it is the perception by the public and coaches that these are the only available mouthguards? Indeed, most mouthguards today do not fit, are bulky, and do interfere with speaking and breathing because they are wearing stock or boil and bite mouthguards! The majority of athletes are not wearing properly made dentally diagnosed and designed custom made mouthguards provided by your sports dentist.
As sports dentists and health professionals interested in injury prevention, we do not recommend store bought boil and bite mouthguards to our patients and athletic teams. The public deserves the best quality of care in injury prevention and boil and bite mouthguards DO NOT provide this quality. See photo of Boil and Bite Mouthguard after use for several weeks.