With interdigitation the upper and lower jaws work in concert as a functional block, which is the strongest position of the dental arches and jaw-joint complex. This can be demonstrated by the facial distortion of a boxer wearing a mouth guard. This is the evil intent of mouth guards. X-rays also reveal fractured and scarred bone patterns of the jaw joint and base of the skull of soccer players as the result of the jaw joint being forcefully and repeatedly impacted during play. The amount of force at the moment the ball impacts against the head of a soccer player is 208 joules.
Every force produces an equal and opposite directional component of force.
Since the lower jaw is not attached to the cranium or skull, at the moment the ball impacts the head, the lower jaw slams against the base of the skull. These forces account for a large percentage of the damage found in the jaw joint and the base of the skull of soccer players. We must safeguard the most vulnerable and vital joint that even supports the brain. It is essential that we evaluate the mechanism of injury in sports in the way they occur during play. In hockey players the scarred and fractured bone patterns identified in the jawjoint complex and surrounding structures is more defined and of greater size.