Braces utilize the mouth’s existing teeth-moving mechanism by applying pressure in the direction of the desired movement. This is done with a wire laced through metal brackets affixed to the outside of the teeth that’s then usually anchored to brackets on the back teeth to maintain constant tension.
This anchorage set-up alone, however, may not work effectively with all bite situations, which might require other points of anchorage. That’s where these other tools in the orthodontist’s toolkit can come in handy.
Headgear. These appliances not only aid with moving teeth but they also help influence the proper growth of facial structures (as when one of the jaws is too far forward or too far back). Because of this influence on jaw growth you’ll only find them used with pre-teens. The most typical application is a strap running around the back of the head or neck (or sometimes over the chin or forehead) that attaches in the front to brackets usually bonded to the molars. In this case the back of the patient’s skull serves as the anchor point.
Temporary anchorage devices (TADs). Orthodontists sometimes wish to isolate the teeth to be moved from nearby teeth that shouldn’t be. For example, they may want to move front teeth back to close a space without the back teeth moving forward. In this case, it may be necessary to create a separate anchorage point in the jaw. This can be done with TADs, which are made of either biotolerant (stainless steel, chromiumâ??cobalt alloy), bioinert (titanium, carbon), or bioactive (hydroxyapatite, ceramic oxidized aluminum) materials and shaped like mini-screws. Orthodontists insert them into the bone and then attach them to the braces using elastics (rubber bands). After completing orthodontic treatment they’re easily removed.
Elastics. We’ve already mentioned them, but elastics deserve their own category because they can be used in various kinds of anchorage. They play an important role, for example, in cross-arch anchorage that maintains tension between the upper and lower jaws. They can also be used to help move one or more groups of teeth — or isolate certain teeth from moving. They truly are flexible (no pun intended) in their uses for fine-tuned tooth movement.
All these devices can be used in various combinations to match and correct whatever bite situation a patient may have. The end result is straighter and better-functioning teeth — and a more attractive smile.
If you would like more information on orthodontic treatment, please contact us or schedule an appointment for a consultation. You can also learn more about this topic by reading the Dear Doctor magazine article “Orthodontic Headgear & Other Anchorage Appliances.”
Most of us are quite familiar with what traditional braces look like. But occasionally we see more complex-looking devices being worn by young orthodontic patients: thicker wires that extend outside the mouth, with straps that may go behind the neck or over the chin. What are these devices, and why are they sometimes needed?
In general, orthodontic appliances with external parts braced by the head, neck or chin are referred to as “headgear.” These devices may be used to handle a number of particular orthodontic situations, but they all have one thing in common: They provide the additional anchorage needed to move teeth into better positions.
It may come as a surprise that teeth, which seem so solid, can actually be moved fairly easily over time. This is because teeth are not fixed directly into bone, but are instead held in place by a hammock-like structure called the periodontal ligament. Using a light, controlled force — such as the force of springy wires and elastics in traditional braces — teeth can be moved slowly through the jaw bone, like a stick being pulled through sand.
Of course, to pull a stick through sand, you need a firm anchorage — your legs, for example, bracing against a rock. Most of the time, the back teeth, with their large, multiple roots, provide plenty of support. But sometimes, the back teeth alone aren’t enough to do the job.
If a very large space between teeth is being closed, for example, the back teeth might be pulled forward as the front teeth are pulled back; this could result in poor alignment and bite problems. In other cases, the front teeth may need to be pulled forward instead of back. The back teeth can’t help here; this is a job for headgear.
Some types of headgear have a strap that goes behind the head or neck; they use the entire head as an anchorage. Other types, called “reverse pull” headgear, have a strap that comes over the chin or the forehead; they can pull teeth forward. Headgear can even influence the proper growth of facial structures — that’s why it is usually seen on preteens, whose growth isn’t yet complete.
Headgear is usually worn for 12 hours per day, for a limited period of time. In some cases, rather than headgear, appliances called “temporary anchorage devices” (TADS) may be recommended. These are tiny screws that are implanted into the jawbone in a minimally invasive procedure, and serve a similar function.
While it may not look pretty, orthodontic headgear is capable of moving teeth into their proper positions in a relatively short period of time — and ending up with a great-looking smile is what orthodontics is all about.