What youre describing sounds like a condition called Bruxism. Its an extremely common problem between both children and adults alike, its just people dont actually recognise it to be a condition, more of just an annoying habit. Treatment ranges from a simple plasticy rubbery mouthguard, which is the preferred option, and in extreme cases, relaxant medication. If its becoming a problem, id suggest to book a check-up with your family dentist, and discuss it with them. I used to be a dental nurse, so any questions you have im more than happy to help. Please keep in mind im NOT a dentist, and dont know everything, but I can certainly guide you along the right path and answer a ton of questions. Good luck!

Try chiropractic adjustment.  Chiropractic care for infants and children is very gentle and can help tremendously.  My dear friends dd would grind her teeth horribly at night and after a few chiropractic adjustments, she stopped.  If you are in the US you can go to www.icpa4kids.org to find a pediatric chiropractor.

I found this Information on Web M.D

My Son and My Boyfriend both grind their teeth, It is extremely irritating and like you said likr Nails on a Chalkboard. Hopefully this helps.

The problem of teeth grinding is not limited to adults. Approximately 15% to 33% of children grind their teeth. Children who grind their teeth tend to do so at two peak times – when their baby teeth emerge and when their permanent teeth come in. Most children lose the teeth grinding habit after these two sets of teeth have come in more fully.

Most commonly, children grind their teeth during sleep rather than during waking hours. No one knows exactly why children grind their teeth but considerations include improperly aligned teeth or irregular contact between upper and lower teeth, illnesses and other medical conditions (such as nutritional deficiencies, pinworm, allergies, endocrine disorders) and psychological factors including anxiety and stress.

Grinding of the baby teeth rarely results in problems. However, teeth grinding can cause jaw pain, headaches, wear on the teeth and TMD. Consult your dentist if your child's teeth look worn or if your child complains of tooth sensitivity or pain.

Specific tips to help a child stop grinding his or her teeth include:

• Decrease your child's stress, especially just before bed.

• Try massage and stretching exercises to relax the muscles.
• Make sure your child's diet includes plenty of water. Dehydration may be linked to teeth grinding.
• Ask your dentist to monitor your child's teeth if he or she is a grinder.

   

No intervention is usually required with preschool-age children. However, older children may need temporary crowns or other methods, such as a night guard, to prevent the grinding.