(HealthDay News) -- Many children suck their thumbs, but it can cause dental problems if children continue to suck their thumb beyond age 4.

Most children stop on their own, but continued thumbsucking could be a sign of a behavioral problem, such as anxiety or depression.

The U.S. National Library of Medicine offers these suggestions to help your child quit the habit:

• Ask your pediatrician about having your child use a thumb guard.
• Apply a bitter-tasting material on your child's thumb. But always check with the child's doctor to make sure it's safe.
• Make a deal with your child. If he or she agrees to stop sucking the thumb, offer a reward.
• Offer praise and attention when you notice that your child isn't thumbsucking.
• If your child's teeth have been affected by thumbsucking, talk to the child's dentist about what can be done to correct it.