The Herbst Appliance promotes jaw growth.
What does the Herbst Appliance do?
The Herbst appliance prevents the lower jaw from moving backward although opening and closing movement still occurs easily. The device is attached to the back molars on the upper and lower jaws with bands that are cemented into place. Patients using the Herbst Appliance do not have any problems learning to chew their food with their lower jaw in this new position.
The Herbst appliance is designed to correct bites and improve facial profiles. The most common bite problem the Herbst® will correct is when the upper teeth protrude too far beyond the lower. We tend to think that the upper jaw and teeth are too far forward but, more often than not, this condition is due to a small lower jaw that is further back than it should be.
The Herbst will encourage the lower jaw to catch up in growth. The appliance is cemented and will work for even the most sensitive patient because a constant force is much less painful and disruptive than intermittent forces, like a head gear, and is much more predictable as far as results. It is called a “functional” appliance because it causes the patient to function (speak, swallow, and eat) in a new jaw position. If the patient functions in this new position for long enough, the change becomes permanent.
It is often necessary to expand the upper jaw while the lower jaw advances, this is done with the addition of a Palatal Expander. The PSA is turned with a special key until the upper jaw is wide enough. The doctor will advise you about using the key and what to expect from this combination.
The Herbst appliance is very effective in correcting large overbites due to small lower jaws in patients who are growing. The Herbst appliance is used to enhance the growth of the lower jaw in a forward direction, while at the same time applying pressure to the upper jaw in a backwards direction. Expansion may also be achieved in the upper jaw if desired.
A tube and rod work together similar to a shock absorber to connect the upper and lower jaws. This does not interfere with opening and closing the mouth or with eating. Side to side movement is somewhat restricted. The Herbst appliance is cemented on the back molars and is in place and active 24 hours a day. It is generally worn full time for 12 months along with front braces. Once it is removed, braces are added to the side teeth for an additional 12 months to complete tooth alignment.
On occasion, the Herbst appliance may become loose and the rods could pop out. Sometimes the rod can easily be popped back in place if it has only come off the groove. If the rod has popped out completely, the orthodontist will need to reattach the piece. Athletes who have this appliance typically have to wear special mouth guards to protect the appliance from being jostled in the mouth.
As with all kinds of braces, patients with the Herbst® need to be careful about what they eat. Hard, sticky, chewy and crunchy foods can loosen the cement and pull the braces from the teeth. Don’t play with the appliance with your tongue or fingers. More braces are damaged by these careless habits than any thing else.