I agree with the comments by Dr. Jeffrey Hoy. As sports dentists we have heard of and seen situations which may indicate a connection between the use of an intraoral appliance and the reduction in occurrence or severity of concussions. We have reviewed the dental literature starting with the work of Jack Stenger in the mid 1960's. However, in light of the current concepts of the causes and physiology of concussions, neither of these two can be considered either proof or even solid evidence of an effect. I look forward to future research on this very important topic but at present, there is absolutely no definitive research upon which to make claims of a protective effect from a mouthguard on concussions.