Functional Appliances to Correct Bite Problems | Saint Louis South Orthodontics

Orthodontic treatment often uses braces or clear aligners to move teeth, but for more serious bite problems, we may recommend functional appliances. These devices use natural forces from muscle activity and jaw growth to align the bite. Examples include the Activator, Bionator, Twin Block, and Herbst appliances. Some are fixed like braces, while others are removable. Unlike braces, they work mainly by repositioning the lower jaw to improve bite development. They are most effective during jaw growth (around puberty), but some can be used in adults.

Functional appliances are central to interceptive orthodontics, which guides jaw growth early to improve function and appearance, often reducing future brace time. Other interceptive devices include palatal expanders and headgear; some functional appliances can replace or combine with these.

Commonly Used Functional Appliances

Bionator

A "Bionator" is the generic term for a family of removable appliances that are designed to move the lower jaw into a more forward position. This is often desirable when the top teeth rest too far in front of the bottom teeth, resulting in a type of malocclusion (bite problem) called on overjet. Like a retainer, the bionator is removable, and is held to the top teeth by means of a wire. Made of acrylic (plastic), the bionator generally has an upper part that sits behind the front teeth, and a lower part that contacts the bottom teeth. When the jaw is closed, the inclined shape of the lower part causes the bottom teeth to move forward. Over time, this re-positioning creates skeletal and muscular changes in the jaw, which can bring the bite into better alignment.

Twin Block Appliance

The twin block appliance is similar in function to the Bionator, but is made in two pieces instead of one; this makes it less bulky and more comfortable for some patients. The top half of the twin block is held to the upper teeth by flexible wires, and a similar method holds the bottom half to the lower teeth. When the jaws are closed together, the two halves of the appliance meet — and the inclined surfaces at the meeting point cause the lower jaw to move forward. Twin block appliances are generally removable, but can be fixed in place when required; they are designed to be worn 24 hours a day. These versatile appliances can be designed to include components like expansion devices, clasps and springs, so they can be customized for an individual's needs.

Herbst Appliance

The Herbst appliance is generally fixed to the molars (back teeth) on top. From there, a small tube and rod, somewhat like a tiny shock absorber, extends down to a fixed point on the bottom teeth. This mechanism puts a constant slight pressure on the lower jaw, causing it to develop in a more forward position. Wearing a Herbst appliance often produces a noticeable effect in a relatively short time; typically, the appliance is worn for about 12 months.

Because it is non-removable, compliance is not an issue with the Herbst appliance, as it may be with headgear or a removable device. It is possible to eat and speak normally with the device; however, like many fixed appliances, wearing the Herbst appliance may cause minor discomfort at first. This can usually be alleviated by eating softer foods, rinsing with salt water, and using dental wax, and most people grow accustomed to the appliance in a short time.

Wearing a Functional Appliance

Whether you wear a fixed or removable functional appliance, you still need to maintain good oral hygiene during treatment. Removable appliances should be taken out for your regular routine of brushing and flossing. You should also clean the appliance itself as directed, and wear it as often as recommended otherwise, it can't do what it's supposed to do! Fixed appliances sometimes pose a greater challenge for cleaning. However, there are many products available like floss holders and interdental brushes that can help you get the job done. If you have questions about how to keep your teeth clean with oral appliances, ask for some pointers at your next appointment.

After you have finished wearing a functional appliance, traditional appliances such as braces or aligners may be needed to complete your orthodontic treatment. However, functional appliances may reduce the time you need to wear braces, and can often correct problems that would otherwise require even more complex treatments, such as oral surgery. These appliances can help you get a great-looking smile and a bite that works the way it should.

Orthodontic Headgear

Headgear is often used to correct an excessive overbite. This is done by placing pressure against the upper teeth and jaw, which would hold the teeth in position or help move them into better positions. The severity of the problem determines the length of time headgear needs to be worn. The key to success with your headgear appliance is consistency. Headgear must be worn a certain number of hours per day, and if not, it must be made up the following day. Headgear should never be worn while playing sports and should also be removed while eating or brushing your teeth.

Palatal Expanders

A major benefit of receiving orthodontic treatment in childhood is that it's possible to take full advantage of a youngster's own natural growth process to treat or even prevent malocclusions ("bad bites"). A palatal expander is a device designed to help us do that. Palatal expanders create more space in a child's mouth by gradually widening the upper jaw. Although this may sound scary, it's really quite easy — both to do and to tolerate. That's because the upper jaw (maxilla) actually develops as two separate halves that don't completely fuse together until sometime after puberty. Before that happens, the two bones can gently be separated and stabilized over a period of several months.

The three situations that most commonly call for maxillary expansion are:

Crossbite

When a child's upper jaw is too narrow to fit correctly with the lower jaw, the back top teeth will bite inside of the lower teeth instead of outside. This can be corrected by expanding the upper jaw.

Crowding

Even before all of a child's permanent (adult) teeth come in, we can tell when there will not be enough room to accommodate them. Widening the upper jaw can create the necessary space without the need for tooth extractions.

Impacted Teeth

When a tooth that hasn't come in (erupted) yet because it is blocked by other teeth, widening the upper jaw can allow it to erupt into proper position on its own. This most often happens with canine or eye teeth — the pointier ones located directly under the eyes.

How Expanders Work

An expander is custom-made for each individual and fits over several top teeth in the back of the mouth. The appliance has two halves that are connected in the middle with a screw. To activate the device, you simply turn the screw a very small amount each day with a special key. This induces tension at the junction of the two palatal bones, causing them to gradually move apart. Once the desired expansion is achieved, we will leave the appliance in for a few more months to allow new bone to form in the gap and stabilize the expansion. Generally, expanders are worn for 3-6 months altogether.

What to Expect

There can be some soreness or a feeling of pressure for a few minutes after the key is turned, but activating an expander actually causes less discomfort than having braces tightened. Your child may find that speaking and eating feels different at first as the tongue adjusts to the presence of the appliance. It is also completely normal to see a gap develop between the front teeth. This shows that the expander is having the desired effect. When all is said and done, your child's permanent teeth will be beautifully aligned with neither too much nor too little space between them.