Sports mouthguards are custom-made rubber coverings worn over your teeth to protect them from damage in contact and ball-based sports. They cushion the teeth and gums and help to avoid chipped and broken teeth.
You should wear a professionally-made sports mouthguard at all times when playing any sport involving either moving objects or physical contact.
Being hit in the mouth by a ball in such sports as football, cricket or hockey can lead to serious damage to your teeth, including broken and lost teeth, while sports in which you come into contact with other players, such as rugby, American football and boxing, can also lead to damaged, broken or dislocated jaws.
Sports mouthguards provide cushioning to protect against such injuries. Professional sportspeople can often be seen wearing mouthguards for this reason.