The technical term for teeth grinding is bruxism. It is a natural habit for babies to initially grind their teeth, typically while they are at sleep. Therefore, if you hear teeth grinding noises you should not be overly concerned.
However teeth grinding should stop when all milk teeth have erupted. If your child still grinds during the night at the age of five or older we recommend to see your dentist.
Bruxism can be triggered by several factors such as a misaligned bite, or as a subconscious pain relief originating from the teeth or ears.
Frequently bruxism is caused by stress such as changes in the domestic environment or school related problems. A relaxed calm evening routine and discussing daily problems with your child can help to reduce the grinding in these cases. In general bruxism should stop during puberty, if not then a night guard is needed to prevent teeth getting worn down.