Crib appliances are utilized to eliminate adverse tongue, finger, or thumb habits. They are usually cemented to the upper permanent first molars. However, the appliance may be fabricated so that it is removable for those patients playing particular wind musical instruments (sax, clarinet, etc.). Crib appliances are utilized anywhere from three months to two years depending on the persistence and nature of the habit. They are designed to disrupt the placement of the thumb and fingers within the mouth, thus preventing the suckling action against the palate. Equally, the orthodontic crib appliance will dissuade forward tongue posturing and thrusting.
Tongue thrusting, or forward resting tongue posture, can distort the upper jaw and promote flaring of the upper front teeth (the incisors). Often an open bite and/or crossbite of the back teeth will result as well. Dental arch crowding may eventually ensue due to the constriction of the upper jaw caused by constant pressure on the palate. The Crib appliance is a mechanical, non-volitional, habit-breaking appliance. The volitional modalities for treating these problems are usually rendered in school, private speech therapists, or myofunctional therapists, by making use of different speech and tongue practices. If a Crib appliance is placed, it may interfere with these volitional exercises.
Aggressive finger and/or thumb sucking, or even long-term pacifier habits, may retard upper jaw growth and create flaring of the upper front teeth. Retardation of the downward growth of the upper jaw, or maxilla, may result in a skeletal openbite. Elimination of such habits is vital for the normal development and maturation of the facial structures.