Sports Dentistry: Mouthguard Research No Longer Limited to Trauma Prevention

ABSTRACT

Background

Mouthguards have been used for dental trauma prevention for many years. As materials and techniques have improved, so have their prevention and functions. We are now able to use these materials and techniques to further our knowledge of concussion events, as well as potential athletic performance benefits.

Types of Studies Reviewed

An electronic search of Pubmed from 1985 to 2022 examining mouthguard materials and techniques, and current research usage. Twenty-eight articles were reviewed.

Results

Mouthguards are proving to be vital to precise concussion research, as well as athletic performance potential.

Practical Implications

As practicing dentists, it would behoove us to further our knowledge about the potential benefits of well-fitting mouthguards for our patients. To learn more about these subjects and current research being completed, contact the Academy for Sports Dentistry.

KEYWORDS:

• Mouthguards
• types I, II, III
• concussion research
• athletic performance
• oral trauma
• oral appliance
• dental trauma

When discussing oral appliances in sports dentistry, it must involve a mouthguard. In the sports dentistry arena, mouthguards have been the primary defense against orofacial trauma. A dental mouthguard helps protect our athlete’s dentition and oral structures¹ and has greatly improved over time. In years past, rubber-based materials were used to make athletic mouthguards. The problem was, because of the poor fit, the athlete was forced to hold it in place by clinching, which by nature, could compromise the athlete’s breathing and air flow. Therefore, a newer material was developed: ethylene vinyl acetate (EVA). EVA has been the dental material of choice for dental mouthguards for many years.² It is seen in various forms, shapes, colors, designs, inserts, and thicknesses but EVA serves as a preferred base material.^3,4 There are three main types of mouthguards: type I-stock mouthguards (off the shelf), type II, mouth-fitted (shell-liner and boil and bite), and type III, custom-fabricated.⁵ Mouthguards have been recommended and proven to reduce the incidence of dental injuries.^6,7 While the value of an athletic mouthguard is undeniable, sports dentistry has become more than preventing trauma. Data is now being collected on the use of mouthguards in concussion research and the potential of improving an athlete’s performance.

A type I mouthguard is found in most sporting goods stores. It is purchased and worn, as is. They may or may not come in different sizes but are worn right out of the package. They are inexpensive and readily available but since there is not a fitting to the particular athlete, the fit is poor and relies on the athlete to hold them in while clinching. Similar to the type I is the shell-liner and/or boil and bite mouthguards (type II).⁸ Athletes who are required to wear a mouthguard in their sport, at all levels, are exposed to the type I and II mouthguards. Differing from the type I, a shell liner or boil-and-bite mouthguard is bought from a local sporting goods store, heated in water and self-molded to the athlete’s dentition by the athlete. The athlete can mold it from home or wherever warm water is available. The benefit for the type I and II mouthguards is that they are readily available, inexpensive, and meet the minimum equipment standard for sports that require them. The negatives of this oral appliance are that they do not fit well, they are difficult to speak and breathe with, tend to fall out, and do not hold up as well.⁹ In the Dr Seals report, a two-page questionnaire was sent out to all 1,032 Texas high schools who played varsity football. Five hundred and seventeen were returned. The questionnaire asked them to evaluate mouthguards and oral injuries. Overall, 84% of the schools responding did not use dentist-fitted mouthguards. Six hundred and seventy-four of the athletes or 4% of the 16,871 athletes wore a dentist-fitted mouthguard. A conclusion of the Seals study is that the majority of mouthguards being used are over-the-counter mouthguards that are not acceptable to the athletes in terms of comfort, durability, and speech.⁹

Type III Mouthguards

Using a vacuform machine in the dental office to fabricate a dental mouthguard is a common technique. This machine uses a heating element from above and a suction (vacuum) motor below the dental model to pull-down the heated EVA material over the stone dental model. It is left to cool and then trimmed to best fit the athlete. Some benefits of a vacuform mouthguard are that they are easily and efficiently made, and the machines are available through a dental supplier, as well as multiple size and shape EVA materials. Some of the disadvantages are that since the vacuum pulls the heated EVA material down, the accuracy is likely dependent on the vacuum strength. Also, it can only pull from around the stone model so the dental adaptation is not as accurate on the occlusal surface as the pressure-laminated technique.¹⁰ Because of these factors, a vacuform mouthguard may not fit as comfortably as other techniques.¹¹ There are newer vacuform thermoforming machines that can also incorporate the opposing occlusion, but further study will need to be done to compare fit and stability to pressure-laminated mouthguards. Lastly, it is very difficult to use multiple layers of EVA on a vacuform mouthguard due to a second or third layer not adhering well. A wrestler, boxer, or mixed martial artist will require more orofacial protection due to their high orofacial trauma risk and that protection is gained by additional EVA layers of the mouthguard.

Pressure Laminated Mouthguards

In some form, the optimal option for a mouthguard is a pressure laminated mouthguard.^12–14 In the Kenyon study, athletes wore both single layer vacuformed mouthguards and double layered pressure laminated mouthguards comparing them in 17 characteristics. In 14 of the 17 categories, the double layered mouthguard performed as well or better. There was a statistically significant patient preference for the double-layered mouthguard.¹¹ This technique still uses EVA, in various thicknesses, but uses pressure to compress the soft EVA onto the dental model. This forces the soft EVA into the grooves and embrasures of the dental model allowing a more accurate fit of the mouthguard.¹⁰ The advantages of a pressure laminated mouthguard are an improved fit over the previous types, better airway flow, customized thicknesses for the specific sport, and better athlete compliance. In addition, it allows for different thicknesses for specific sports requirements, as a multi-layer of EVA will meld with the next. There are current data that leaving air space between laminated layers could improve shock absorption.¹⁵ 3-D printed honeycomb-shaped inserts, to potentially further improve shock absorption, are also currently being explored. The disadvantages of a pressure-laminated mouthguard are equipment expense, time needed for fabrication, or lab costs, if manufactured outside the dental office.

The days of mouthguards being used for just dental protection is likely over. Current dental research done around the world is exploring other uses for mouthguards. Concussions are a real result of sports activity and learning more about them is critical. The purpose of this article is not discussing the outcome of the aforementioned concussion research. Rather, it will show that a mouthguard can be used for further data gathering.^16,17 With researchers using an instrumented mouthguard (IM) worn by an athlete during the head blow, it can give them lots of valuable data to develop concussion prevention strategies.^18–20 It can give them the linear and angular acceleration and impact direction and location.²¹ This is critical information in understanding traumatic brain injury. The current research being done uses both type II and III mouthguards. Knowing that a type III mouthguard is better fitting, perhaps more accurate data will be gained while using a type III, instead of a type II. Further research should be done to determine if this makes a difference in data conclusions.

Performance enhancing mouthguards are another area of research. When the difference in winning first or second place is 0.01 s or less, athletes are yearning for every legal option available. Perhaps wearing the mouthguard in a certain jaw position could affect oxygen intake and/or performance enhancement.²² Haughey compared 15 athlete’s normal bite and the lower jaw position when the muscles of mastication are at physiological rest. He had the athlete do different strength, flexibility, and balance tests in each bite position. He found a significant positive effect on the athlete’s performance but that more research is needed.²³ Other recent literature review states that performance enhancement with a bite-aligning mouthguard is inconclusive.^24–26 However, perhaps the type of mouthguard, athlete customized vs. a dentist customized, can affect performance.²⁷ More research is currently being gathered on a mouthguard’s performance enhancing potential.

Oral Appliances in sports dentistry are continuing to improve in design and function, and further research is being done by experts from around the world. We are learning more and more each day as to how to best protect our athletes from dental trauma. With a properly fitted and worn mouthguard, oral trauma rates can be reduced. We are learning to use mouthguards to further research in understanding concussions, and perhaps even reduce their effects. We are learning about performance and balance, and whether we can impact these variables in our athletes. Perhaps having concrete research that clearly shows reduced trauma and improved athletic performance in a noninvasive mouthguard will be the keys to better athlete compliance. We know that a mouthguard is important in reducing dental trauma, is it time to take a unified approach in recommending mandating them to sports organizations?²⁸ These are all topics that will require more research and review. It certainly is an exciting time to be involved with sports dentistry.

Disclosure statement

No potential conflict of interest was reported by the author.

Correction Statement

This article has been corrected with minor changes. These changes do not impact the academic content of the article.

Additional information

Notes on contributors

Xavier J. Gutierrez

Dr. Xavier J. Gutierrez obtained his DDS degree from Northwestern University Dental School in Chicago, IL. He then completed a two-year General Practice Residency at University Medical Center-Fresno (UMC), a level-one trauma center, serving as Chief Resident during his second year. He currently serves as the team dentist for the Fresno State University Athletic Department, Fresno Pacific University Athletics, and Clovis High School Athletics. In 2017 he was awarded the distinction of Fellow of the Academy of Sports Dentistry and currently serving as the Academy’s President.