Mouth Guards and Athletes

Pressure laminated mouthguards: of injuries to athletes’ mouth and brain in contact sports

As a dental hygiene educator, one of the challenges I face is in educating executive committees, coaches, parents, and athletes on the merits of a custom fit, laminated mouthguard. While any mouthguard will provide a certain level of protection against tooth and orofacial injuries, it is only a quality, custom fit, laminated mouthguard that may actually provide some level of concussion prevention or reduced traumatic brain injury (TBI).¹

The subject is being investigated by the sports industry as well as by research specialists in medicine/neurology. The three possible theories are:

1. direct dissipation with or without absorption of force of an upward blow to the jaw,
2. increased separation of the head of the condyle and glenoid fossa,
3. increased head stabilization by activating and strengthening neck muscles.¹

Concussion can be defined as a short lived loss of brain function due to head trauma that resolves spontaneously. With concussion, function may be interrupted, but there is no structural damage to the brain. The brain floats in cerebrospinal fluid, and is encased in the skull. These protections allow it to withstand many of the minor injuries that occur in day to day life.

However, if there is sufficient force to cause the brain to bounce against the rigid bones of the skull, then there is potential for injury. It is the acceleration and deceleration of the brain against the inside of the skull that can cause the brain to be irritated, and interrupt its function. While temporary loss of consciousness due to injury means that a concussion has taken place, most concussions occur without the patient being knocked out. The International Conference on Concussion in Sports recommended that concussion be divided into two groups — simple and complex.

In a simple concussion, the person’s symptoms gradually resolve, and the patient returns to normal function in 7–10 days.

In complex concussions, symptoms persist and thought processes are affected. Athletes with repeated concussions would fall into the complex category.²

The four choices for mouthguards are:

1. Stock (already made) which are inexpensive, but do not offer as good a fit or comfort for breathing and speaking as other types of mouthguards. They offer the least protection.
2. Mouth formed (boil and bite mouthguards) are relatively inexpensive. They are molded in the mouth after being softened in boiling water. They come in limited sizes, and with little attempt at proper fit.
3. Custom formed are made by a dentist or dental hygienist from a model of an athlete’s mouth using a vacuum machine. Until recently, they were believed to be the best type of mouthguard available. Over time they can change and become loose, with thinning and perforating. There is no way to ensure their proper thickness.
4. Then there are pressure laminated, custom made on a model from several layers of mouthguard material in a special heat/pressure lamination machine. Due to the method of production the material maintains its fit and protective thickness over prolonged periods of time.³

Whether mouthguards are eventually shown to prevent concussion or not, they are very important to wear because they protect an athlete’s teeth, mouth, lips, cheeks, gums, tongue and jaw.³

The late Dr. Tom Pashby was involved with the hockey team, Toronto Maple Leafs, and chaired the Canadian Standards Association from 1975–1995. Dr. Pashby, an opthalmalogist, became involved due to the number of eye injuries that hockey players received during play. Dr. Pashby was instrumental in advocating the use of safety equipment for hockey players including mandatory helmets and faceguards.

According to Pashby Sports Safety Fund Concussion Site,3 the following guidelines should be followed regarding mouthguards:

1. They should cover all teeth, including molars.
2. Children aged 6–14 should have their mouthguards checked approximately every 3 months.
3. Athletes younger than 16 years should replace their mouthguards annually.
4. Adults should replace their mouthguards every two years because mouthguards lose their resiliency and flexibility over time.³

The Canadian Dental Hygienists Association position statement⁴ on sports mouthguards research shows that orofacial injury in sports is prevalent, and carries significant medical, financial, cognitive, psychological, and social costs. Research also confirms that mouthguards can prevent orofacial injuries.⁴ The CDHA therefore strongly recommends that dental hygienists play an integral role in the prevention of orofacial injury in sports, and that dental hygienists promote properly fitted mouthguards as an essential piece of protective equipment in sports that present a risk of orofacial injury at the recreational and competitive level, in both practices and games.⁴

A study article published in Journal of Athletic Training⁵ stated the greatest emphasis was on the thickness of the guard in the posterior areas, that thickness being 3–4 mm. The only way that this is achievable is through the use of a heat/pressure laminate machine such as a Drufomat. The material used in this study was a polyvinyl acetate copolymer, but there are different types of vinyls used and studied.⁵ Over the past 35 years, quality has been sacrificed for a quick fix, that is, low cost, ill fitting mouthguards. These mouthguards do not hold their shape, and fit so poorly that athletes sometimes alter them for speaking and comfort, foregoing the posterior thickness that might provide needed protection if a blow were delivered to the mandibular complex. Also stated in the article⁵ was, "… education of all those involved is the key."

A study, published in Dental Traumatology⁶, compared energy absorption of three mouthguard materials. The three materials studied for energy absorption were ethylene vinyl acetate (EVA, T&S Dental and Plastics), ProForm (Dental Resources Inc.) and Polyshok^™ (Sportsguard Laboratories). The three materials were tested in three different environments, and it was concluded that the Polyshok^™ material showed superior energy absorption attributed to the polyurethane additive to the material.⁶

In a recent study by Benson, Rose and Meeuwisse⁷ at the Faculty of Medicine, University of Calgary, specific risk factors to ice hockey players wearing full face shields compared with half face shields (visors) were investigated. The results included players wearing mouthguards with half face shields and full face shields. Players who wore half face shields and no mouthguards at the time of concussion missed significantly more playing time (5.7 sessions per concussion; 95% Confidence interval 2.14 to 3.55). Players who wore full face shields and mouthguards at the time of concussion lost no playing time compared with 1.80 sessions lost per concussion (95% Confidence interval 1.38 to 2.34) for players wearing full face shields and no mouthguards.⁷

The number of mild traumatic brain injury (MTBI) and cerebral concussions is increasing, and cannot be eliminated by any kind of equipment. Prevention strategies, such as the introduction of "checking from behind" rules, have become effective in decreasing the number of severe spinal injuries.¹ A new "head checking" rule should reduce MTBI in the same way in the following years. Mouthguards should be mandatory as an effective device for the prevention of dental and orofacial injuries, as well as in reducing the incidence and severity of MTBI.

The damage that concussions can cause to the brain is being studied more than ever. Boston University Medical School opened the Center for the Study of Traumatice Encephalopathy in 2008, and researchers there, such as Ann McKee, have so far studied the brains of six deceased athletes to understand the damage that concussion causes. Dr. Brian Benson’s recent analysis of data, on NHL ice hockey players over one season, is to be made public soon. Every person who is involved at one level of sports or another has a responsibility to see that their athletes are playing as safely as possible.

In conclusion, from research and reading many articles on sports injuries, I draw on three commonalities:

• there is a lack of educationnd mouthguard use,
• more research is needed to study the merits of mouthguard use, and third,
• more mouthguard use is needed.

Regards
Bernadette MacKay, RDH

References

1. Biasca N, Wirth S, Tegner Y. The avoidability of head and neck injuries in ice hockey: an historical review. Br J Sports Med. 2002;36:421–22.
2. Wedro BC, and Stoppler MC. What is concussion and what causes concussion? [Cited 2010 October.] Available from: http://www.medicinenet.com/brain_concussion/article.htm
3. Leclerc S , Shrier I, Johnston K. Risky Sports. Available from: http://www.thinkfirst.ca/downloads/concussion/DrTomPashbySportsSafetyConcussionSite.pdf
4. The Canadian Dental Hygienists Association. Putting more bite into injury prevention. CJDH. 2005;39:6:257–82.
5. Winters JE. Role of Properly Fitted Mouthguards in Prevention of Sport-Related Concussion. J Athl Train. 2001;36(3):339–41. Available from: http://www.ncbi.nlm.nih.gov/pmc/articles/pmc162236/
6. Hunt DR , Mendel DA, Brantley WA, Beck FM, Huja S, Schriever SD , Grentzer TH , Alapati SB. Impact energy absorption of three mouthguard materials in three environments. Dent Traumatol. 2010;26(1)23–29. Available from: doi 10.1111/j.1600- 9657.2009.00848.x
7. Benson BW, Rose MS, Neeuwisse WH. The impact of face shield use on concussions in ice hockey: a multivariate analysis. Br J Sports Med. 2002:36(1):27–32. ©CDH A