The primary image surrounding orthodontics is a metal, train-track smile. We see it plainly in orthodontics offices’ logos: brackets and wires and bands. Fixing a smile has long been a very public and noticeable affair. There is even evidence that braces existed in some form as far back as ancient Egypt! So it can be puzzling to look at Invisalign®, with its innocuous plastic trays, and understand how it achieves the same effect. The trays a patient wears more closely resemble a clear retainer or mouth guard. And mouth guards do not make teeth move. So how can plastic affect our teeth as much as metal fixings, and how does Invisalign move our teeth?
Broken down to basic form, Invisalign (or any generic clear aligner) is a series of plastic trays that gradually move the teeth through constant pressure. The trays are unique to each patient and based on a mold or 3D scan of their teeth. A patient receives a series of trays, changing them out once every 1-3 weeks, that fit snugly to the teeth until the goal smile is achieved. Invisalign has been increasingly popular since its market drop in 2000, because of its inconspicuous and almost unnoticeable appearance when compared to braces. They also make dental care much easier throughout treatment, as instead of flossing or brushing through the brackets a patient can simply pop the tray out. Patients also are not restricted with what they can eat while using Invisalign as it pops out before eating. This results in popcorn or gum posing no threat to the tray. Despite the boon of being able to take the tray out, they must be worn for a minimum of 20 hours a day for optimal results.
The mode by which the constant pressure causes the teeth to reshape is fascinating and makes use of a trait of the human body known as bone remodeling. Orthodontic treatment is the use of pressure to move the teeth. A constant pressure on the tooth results in dental reshaping through the periodontal ligament, which sits between the root of the tooth and the alveolar bone within the jawbone. This ligament is why teeth have a slight wiggle to them. The constant pressure moves the teeth, while cells known as osteoclasts remove bone in the direction the tooth moves, whilst also building up bone in the space left behind. This results in the tooth moving in the direction of the pressure: up, down, left, right, wherever it may go.
Traditional braces use brackets and what is known as an archwire to specify pressure on different areas of the tooth to control its movement. Invisalign does not have these metal brackets and instead uses something called attachments, which are dabs of composite material applied to the teeth. The attachments act as the lever which the rapidly changing aligner trays use to move the teeth. The attachments can be in different spots on the tooth depending upon which direction the orthodontist wants the tooth to move in. The specificity of their location helps ensure that pressure is being applied to the correct areas and that the orthodontist can create the correct smile.
So Invisalign trades the tightening archwire for a snug and changeable tray, and substitutes tooth-colored attachments for the silver buckle brackets. That is how simple plastic can move our teeth, even without the bulk of braces. That does not mean Invisalign is a magic alternative though. As with braces, maintaining the dental positions post-treatment is crucial. The osteoclasts around the moved teeth need time to build back up the bone, so a patient’s detention is highly susceptible to reverting to its original positions if not maintained through the wearing of a retainer. Just as the teeth move, they can be reverted in the same way.
If you are located in West Chester, Pennsylvania, and want to learn more about our Invisalign treatment, please call 484-887-0777 to schedule an appointment with Dr. Sara Bekyan and her team at Westtown Dental Care.
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