Invisalign clear aligners have transformed the way we straighten teeth. Gone are the visible ‘bracket and wire style’ fixed appliances in favour of a series of clear plastic aligners known as trays.
With this in mind, one of the questions we’re often asked by anyone considering their teeth straightening options is, “How does Invisalign move teeth?”
The short answer is that it’s really down to biomechanics, or rather…
Controlled force application + Soft and hard tissue response = tooth movement.
While that may not mean much to you now, by the end of this article you’ll have a good understanding of how this process works. So let’s dive in…
Controlled force application
At the heart of Invisalign’s clear aligner system lies a combination of cutting-edge materials and state-of-the-art design. While the material (a specialised thermoplastic, manufactured to be lightweight, comfortable and flexible) is designed to fit snugly over the teeth, the technology behind the design is nothing short of genius.
Advanced computer-aided design (CAD) technology creates a virtual model of your teeth. Dentists can then virtually plan a step-by-step movement of your teeth using Smile Design technology. The details are signed off and uploaded to Invisalign who will then make a series of custom-clear aligners based on your requirements.
Rather than one fixed appliance doing all the work, the entire movement is split between a series of aligners – sometimes more than 30 trays. Each aligner is designed to move the teeth a tiny fraction (approximately one-third of a mm) over several weeks. When the aligner has done its job and moved the teeth, it’s discarded for the next one in the series – This is controlled force application.
Tooth movement
We’ve gone some way into explaining how Invisalign moves teeth but what actually happens during the tooth movement process?
Let’s find out…
Every time an aligner (tray) is worn over the teeth, it applies what’s known as sustained directional force. In other words, the specific custom-tailored design coerces the tooth into moving in a certain direction. It does this by asserting pressure on one side of the tooth and applying tension on the other.
When this happens, the body responds by breaking down the bone surrounding the tooth in the pressure area and rebuilding the bone in the tension area. As a result, the bone supporting a tooth is in a constant state of restructure. This is why a patient’s aligner typically feels tight for the first few days until staged tooth movement is complete.
Soft tissue response
At the same time, the periodontal ligament (PDL) a soft tissue joint that anchors the root of the tooth into the alveolar bone, also starts to shift. Again, a combination of compression and stretching means that the PDL also undergoes robust remodelling. Studies suggest that this occurs within just a few minutes after forced loading by the aligner. So while you have the movement of the bone tissue in the alveolar, you also have the soft tissue movement of the PDL.
Collectively, the juxtaposing forces of tension and pressure cause the bone and soft tissue to work together to initiate total tooth movement.
Clever stuff, right?
But how can one aligner initiate incremental movements on just one tooth?
A word about aligner attachments
Because movement is gradual, an experienced dentist can also control the precise movement of an individual tooth. This is done using Invisalign attachments. Attachments are invisible bumps or buttons that are attached to the aligner at the appropriate place. Once initiated, they can precisely guide individual tooth movement by applying greater targeted force in any given direction. This causes the soft tissue, bone, and eventually the tooth, to move into an exacting position. Buttons can be positioned over numerous aligner trays to ensure exacting and precise movement throughout the treatment.
How Invisalign moves teeth – What you can expect
So now you know about the science behind how Invisalign moves teeth, what can patients expect during treatment?
Although it appears that a lot is going on under the surface (and indeed there is), Invisalign patients shouldn’t feel much discomfort during treatment as they should be able to continue with daily living.
What patients can expect when wearing their Invisalign aligners is a slight dull aching sensation emanating from their teeth. This is particularly true when a new aligner has just been inserted. This is because most of the movement (particularly associated with the PDL) occurs within the first few hours, so teeth can feel a little tender during this period. This is why dentists often advise patients to change aligners just before they go to bed and take a painkiller as a precaution.
Doing so means that when the patient awakes, the worst of the initial movement is over and they should be pretty comfortable. Even so, any slight discomfort at this stage is expected and is a sign that the process is working.
A new aligner may also appear quite tight at first and you may feel a little pressure on the teeth. But don’t worry, it’s designed to be this way.
A feeling of pressure occurs because the teeth need to shift (grow) into the aligner which can take several days or more to achieve. This is also why patients find that their aligner is more comfortable towards the latter part of the two-week cycle rather than at the beginning.
Then, the process starts all over again when the outgoing aligner is discarded and the subsequent new aligner is inserted.
Although it may seem a bit of a roller coaster ride, patients get used to their aligners the longer they wear them. So for most people, Invisalign treatment remains a comfortable experience.
Besides, any initial discomfort typically pales into insignificance with the outstanding results that Invisalign can achieve.
So there you have it…
Hopefully, this has answered the question of how Invisalign moves teeth and what you can expect during treatment.
If you’re looking for a discreet way to fix your less-than-perfect smile, give the team at Foxbury Dental a call. We’re well-versed in teeth straightening and will give you a thorough examination, talk you through your options and come up with a custom treatment plan, especially for you.
We also provide finance plans that allow you to spread the cost of treatment over several months, so don’t let the initial outlay stop you from getting the smile you deserve.