A mouthguard is an appliance made to protect teeth and surrounding tissue from oral trauma during athletic or physical activities. The mouthguard can be prefabricated or stock, or custom made by a dentist. Custom fit ones have been shown to be more comfortable. For children, they must be changed as new teeth erupt.  It is known that mouthguards can prevent serious injuries such as jaw fractures, neck injuries, concussions, and teeth fractures.  Studies have reported that concussions can be decreased by almost 50% by wearing a mouthguard.  Any activity where there is a strong chance for contact, it is recommended that the mouthguard be worn.