Dr. Tim Walilko – Lead author
In 2010 there were an estimated 1.7 million traumatic brain injuries (TBI) up from 1.4 million in 2004.[1] Despite the increasing number of TBIs sustained every year, there is little information regarding the impact threshold at which they occur or how to prevent them. Five experts in diverse disciplines presented at the May 2011 Oklahoma State Athletic Trainers Associations Conference on potential mechanisms and solutions to jaw joint related concussions. This is a summary of their presentations.
Practical Experience and Observations
Cory Schafer, president of the International Sport Karate Association, with 30 years of experience regulating martial arts and combat sports presented a commonly regarded premise. "If you want to knock someone out, you hit them on the chin". The jaw is the "sweet-spot" for scoring knock outs. Further evidence is demonstrated by terms such as "glass jaw" and "weak chin" which are used to refer to someone who is easy to knock out…." Mr. Schafer also observed that when dual arch jaw joint protection technology is used, the same strike to the chin often does not have the same devastating effect. Based on experience with dual arch mouth guards the International Sports Karate Association is moving towards a mandate for the use of dual arch for all sanctioned events. He posed the question "What exactly is the science behind the dual arch technology that makes it so effective in combat sports, and can it be integrated into helmet sports to better protect our young athletes?"
The Anatomy of a Concussive Blow to the Chin
When a combatant’s punch is directed at the chin of his opponent, a large portion of the applied punch force can be transferred through the mandibular into the structures at the base of the skull. The forces generated by a straight punch to the chin can range from 1,990 to 4,741 Newtons.[1] Forces of the same magnitude can be generated by the chin cup of a helmet after a blow delivered to the facemask. Dr. Ken Moser explained how in both instances the transmitted force travels through the temporomandibular joint (TMJ) into the glenoid fossa and ultimately deforming the structures at the base of the skull. The fossa is so thin that light can pass through this region in a dry skull. Deformation of these thin bones comprising the skull base could affect the intracranial structures within this region. Symptoms include: sensitivity to light; "Migraine" headaches; and radiating headache pain from forehead to eyebrow area. In separate discussions, Dr. Kem Moser and Dr. Robert Mongrain discussed how dual arch oral appliances and the use of energy absorbing materials in their construction could potentially reduce the force of the blow that deforms the structures at the base of the skull.
Test and Evaluation of Protective Devices
Current test standards ignore injuries generated by the forces delivered to the chin. The majority of the standards currently used were developed in the early 1970s when skull fractures and intracranial hematomas were the injuries of great concern in football. The standards developed to address these concerns were based on studies conducted in the 1950s and 60s primarily for the automotive community. While these standards and related rule changes have dramatically reduced the number of skull fractures and intracranial hematomas since 1968, the percentage of concussions has remained relatively constant. The standards and injury criteria developed in 1970 for football have now been modified and applied to include the evaluation of baseball, lacrosse and boxing headgear. In none of these standards are the effects of the forces transmitted through the chin considered.
While the speed of the games and our understanding of the causes of concussion have changed, the standards to which headgear is tested have not fundamentally changed. Currently, strains and strain rate of the brain tissue show better correlation to occurrence and severity of TBI than global metrics such as head acceleration. Head acceleration is what the current standards measures. Numerical models along with focused physical testing are required to make strain calculations. Advances in computing power and fidelity of skull and brain and jaw models now allow these types of calculations to be carried out on laptop computers. With the aid of numerical models, Dr. Walilko illustrated how the forces transmitted to the base of the skull through the chin could soon be calculated using a combination of physical testing and numerical modeling for the development of improved oral appliances.
[1]CDC (2010) Traumatic Brain Injury in the United States: Emergency Department Visits, Hospitalizations. www.cdc.gov/TraumaticBrainInjury
[1]Walilko, T. Viano, D., Cir, C. Biomechanics of the head for Olympic boxer punches to the face. Br J Sports Med. 2005 Oct;39(10):710-9.
Prevention and Treatment
While a treatment for mild TBI has not been developed, Michael Lewis, MD, MPH, MBA, FACPM, drew from several years’ clinical experience using omega-3 fatty acids (fish oil) in patients having suffered a variety of head injuries. Patients ranged from an 18-year old with massive brain damage following a car accident to a 50-year old stroke patient to a young Marine who was victim of blast forces in Iraq have benefited by receiving large doses of fish oil. After a quick review of the science behind omega-3s, the brain, and the constellation of post-concussive symptoms, Dr. Lewis described the doses he has used and detailed outcomes in more than a dozen patients. He finished with several research concepts how best to move this simple, yet highly effective nutritional supplement, to main stream use in sports at all levels for the prevention and treatment of head injuries.
Robert Mongrain, DMD, presented information demonstrating how stabilizing the jaw with a dual arch, dual channel dental appliance can position the jaw in a down and forward position unloading the temporomandibular joint before impact. Based upon the anatomy of that area and the thinness of the bone in the joint this has the potential to reduce forces transmitted through the jaw upon impact. The presented findings are supported by the results of helmeted head drop study tests conducted at Wayne State University (Detroit, Michigan). During these tests a helmet with facemask was dropped 1.5 meters (60 inches) directly onto the facemask. The generated forces delivered directly to the TMJ were as high as 2,200 Newtons (500 pounds). When a dual arch oral appliance was inserted into the articulated jaw headform, the same 1.5 meter drop generated forces in the TMJ 40% to 50% less than the unprotected tests. Stabilizing the jaw away from the cranium and interposing resilient material between the jaws can absorb and reduce forces transmitted through the jaws by direct impact both linear and rotational. These forces can come from impact to jaw or impact transmitted through the protective headgear.
Conference Summary
Five experts from the sports, dental, engineering and medical communities presented their findings on the relationship between the occurrence of jaw joint concussion and the use of oral appliances. Converging evidence from the presentations suggest the use of dual arch oral appliances can reduce the impact of forces resulting in traumatic brain injury… The panel is recommending the use of properly constructed dual arch jaw joint protector mouth guards and omega-3 fatty acids (fish oil) to reduce the neurological effects of blows to the head and chin.
Presenter Biography
Michael Lewis, MD is a Board-certified and a Fellow in the American College of Preventive Medicine. A graduate of West Point, Dr. Lewis spent 31 years in the Army including several years as a lead researcher in traumatic brain injury including product development of a new intravenous acute treatment. Clinically, he has treated dozens of patients with large doses of omega-3 fatty acids with amazing success.
Robert Mongrain, DDS is a 1979 graduate of the University of Florida, College of Dentistry. He currently has a private practice in Tulsa, OK. He is a consultant to the University Of Oklahoma College Of Dentistry. Dr. Mongrain speaks internationally on restorative, preventive dentistry and technology and Jaw Joint protection in sports. He is a member of the ADA, AGD, Academy of CAD CAM Dentistry, Academy of Dental Sleep Medicine, and Academy for Sports Dentistry. He currently is a consultant to several dental companies in biomaterials, technology and sports dentistry.
Kem Moser, DDS has been active in prevention, nutrition, and oral health for the past 30 years of his clinical practice in Kennett Square, Pa. Dr Moser is President of the Penna. Craniomandibular Society and has lectured on myofunctional therapy, temporomandibular joint disorder, sleep disorders, and dietary influences related to ideal growth and orthopedic development. Dr Moser is also a Diplomat of the American Board of Dental Sleep Medicine. Cory Shaffer has been president of International Sport Karate and Kickboxing Association since 1997.
Tim Walilko, Ph.D. is a biomedical Engineer with 20 years of experience in conducting research in human vulnerability to primary blast, blunt trauma, ballistic, fragment, toxic and thermal threats. Dr. Walilko has engaged in research which includes determining a boxer’s punch force to the jaw, the fracture strength of the facial bones to a non-lethal weapon, and determining the strains in the post mortem human surrogates’ mandible resulting from a blow to the chin point with and without an oral appliance.
