Parafunctional Habits:
A parafunctional habit is the habitual exercise of a body part in a way that is other than the most common use of that body part. Oral parafunctional habits may include:
• Bruxism – tooth-clenching or grinding
• Nail or cuticle biting
• Tongue Thrusting – the common name given to a behavioral pattern in which the tongue protrudes through the anterior (front) teeth during swallowing, speech and while the tongue is at rest
• Thumb sucking

Children begin sucking thumbs or fingers at a very early age. Sucking is one of the natural reflexes of the child that provides comfort. Many children suck their thumbs while sleeping because it gives them a sense of relaxation. Pacifiers are often used as a substitute for a thumb or finger.

Most children discontinue a sucking habit on their own, usually between the ages of two and four. There are, however, some children who continue the habit through preschool and into the elementary grades. If your child is sucking his thumb, finger or a pacifier when permanent teeth erupt, it is advisable to begin looking for ways to break this habit.

It is important to understand that these habits can become excessive, and can have an impact on development of the structures of the face, jaws and teeth.