What Exactly is a Tongue Thrust?
A tongue thrust is a muscular imbalance which results in the tongue pushing forward against the front teeth instead of against the palate at the front of the roof of the mouth during the swallowing motion. This habit creates space between the upper and lower front teeth (anterior open bite) and at rest, the tongue protrudes slightly between these teeth. It may also create Class II malocclusion with the upper front teeth being well in front of the lower teeth. This results in greater over jet and less than normal forward growth of the mandible.
It is natural for very young children to have a swallowing motion in which the tongue pushes forward. In most cases, the process abates at an age of around six months, but in a small percentage of children, the habit continues. And if the habit continues, there usually will be associated orthodontic problems which are difficult to correct, speech problems such as a lisp, and minor facial and muscular abnormalities.
The anterior open bite (space between the upper and lower teeth) may cause mouth breathing, the open bite, flaring of the front teeth, speech impediments, and the bite may be open or non-contacting in the back on one side or the other. The tongue usually enlarges beyond normal size in order to fit into the available space. Also, an enlarged tongue (macroglossia) may be the actual cause of a tongue thrust.
Other factors which may be involved in a tongue thrust are anything affecting the movement of air through the mouth and nose. Such things as tonsils, adenoids, thumb sucking, ankyloglossia (tongue tie), artificial nipples, and nasal congestion from allergies affect this air movement. Dry mouth (xerostomia) is often an additional problem.
It is simple physics. Whatever vector ends up with the greatest forces results in movement of bone and teeth in that direction. Since the tongue thrust occurs during the swallowing movement, and since that occurs night and day nearly 2,000 times per 24 hours, the thrust pushes the teeth forward and opens the space between the upper and lower teeth. The lips act as a rubber band holding the teeth back but they are not strong enough to withstand the powerful forces of a tongue thrust. There often may be a lisp associated with this. Other speech problems are created when any of the letters which require the tip of the tongue to touch the back of the upper front teeth are sounded. Such letters as N, T, D, L, S, W, and Z are often compromised.
There are two primary methods of treating tongue thrust. The first is an orthodontic appliance which prevents the tongue from pushing on the front teeth and hopefully retrains the tongue from the habit. But most truly successful treatments require a combination of the above along with “re-educating” the muscles (myofunctional therapy). This is not a simple problem to correct and may have a life-long affect on not only swallowing and breathing, but on speech and dental health.
It behooves every dentist to immediately recognize tongue thrust as this patient will absolutely need exhaustive orthodontic treatment along with myofunctional therapy. Open bite may be caused tongue thrust but also by thumb sucking. Both habits must be eliminated to avoid aesthetic and functional compromise. Also, a person must be able to breathe through the nose in order to swallow properly. If a person can breathe only through their mouth, they usually develop a tongue thrust along with all its associated problems. An orthodontic appliance having a crib or habit reminder is usually required, but as mentioned above, myofunctional therapy, or muscle retraining, is normally required in addition to the habit appliance.
It is known that a tongue thrust is an involuntary and unconscious habit that is difficult to break. The constant 24 hour pressure of the tongue just simply laying in the open bite area in the front, or thrusting forward or even to the side, will force the bone and the teeth out of proper alignment. The teeth may be properly aligned by orthodontic treatment only to relapse later if the tongue thrust is not completely corrected.
There are two basic methods of treating tongue thrust. One is myofunctional therapy which is a re-education of the muscles and usually requires the help of a trained speech therapist. This yields the highest percentage of favorable results. The other method, which is considered to be less successful, is some type of tongue guard which prevents the tongue from pushing forward. This generally works at first but relapses once the appliance is removed. Actually a combination of both methods is probably the most successful. Age seven is the optimum time to begin treatment.
Life Member American Dental Association, Emeritus Fellow of Academy of General Dentistry, American Association of Implant Dentists