First, let me point out that many types of mouthguards are available—from thin, loosely-fitting generic models to precision-fit, pressure-laminated custom units. Regarding tooth protection, most mouthguards offer some benefit; however, the better-fitting, thicker mouthguards are able to absorb and diffuse the impact energy of a given collision leading to greater protection from tooth injury.
Regarding the ability of mouthguards to prevent or reduce brain injury such as concussion, clear-cut evidence has been difficult to gather due to the difficulty of designing adequately controlled studies. However, in a commentary for the Journal of Athletic Training, pediatric dentist Jackson Winter points out, “. . . preliminary work comparing the 1997 through 1999 NCAA college football seasons suggests that (properly fitted, pressure-laminated mouthguards) have made a difference (with respect to concussion resulting from a blow delivered to the mandibular complex).” To effect this protection, he recommended a 3 to 4mm thickness separating the occlusal (chewing) surfaces of the upper and lower posterior teeth.
Given the risks associated with sports-related head injuries and the potential for reducing those risks through the use of pressure-laminated mouthguards, I recommend that such mouthguards be utilized from an early age. Custom fitted, this type of mouthguard requires less bulk and, therefore, is less likely to be resisted; early and consistent use creates a habit that can last throughout a sporting life. More importantly, pressure-laminated guards offer the most effective tooth protection and, if preliminary results are correct, will likely lessen the risk of concussion and brain injury from mandibular impacts.