When your child loses enough teeth, your child's motor mouthpiece needs to be replaced, or if your child is experiencing a growth spurt. Otherwise, the protective teeth are inappropriate and will not protect your child's teeth effectively. Also need to be replaced when the movement teeth are damaged or worn.
If your child does wear a sports mouthpiece, take it for every dental check. Your dentist can take a quick look and let you know if you need to replace it.