The problem: crowded or crooked teeth, gaps in teeth.

Put simply, Invisalign is system which uses invisible, removable appliances to straighten teeth. Teeth are moved using removable, clear plastic trays called aligners instead of the traditional metal wires and brackets. Align Technology, Inc., the company that manufactures Invisalign, was founded in 1997. Since then, Align has manufactured over 10,000,000 aligners and more than 250,000 patients have been in treatment. For years, orthodontists and dentists have used removable appliances for moving one or two teeth. Today, with the application of computer technology and custom manufacturing, Invisalign treats a broader range of cases with greater precision. To straighten teeth, a series of aligners is made, and the patient wears each one for two weeks. Each aligner has the capability to move teeth approximately one-quarter of a millimeter. That does not sound like much in itself, but it quickly adds up to a lot of tooth movement in a few months.

How does it work?

The key to the Invisalign process is the ability to custom manufacture an entire series of perfectly sized aligners from just a single impression of a persons teeth. One of the major differences between Invisalign and traditional metal braces is that we first move teeth on a computer simulation. From this simulation, a computer determines the exact shape of each aligner and makes all of them at once using a process known as stereo laser lithography. A computer guided laser makes a series of models by tracing the shape of each model in a polymer gel, solidifying the gel wherever it touches. The models are simultaneously built up layer by layer until complete, and the aligners are then vacuum formed over the manufactured models.

The concept of using plastic trays to move teeth is not new, but the manufacturing process is. Prior to stereo laser lithography, an impression of a persons mouth would have to be made for every aligner needed. These impressions would be used to make plaster models from which the teeth were cut apart so they could be moved slightly. A plastic tray could then be made to fit the altered model, and this tedious process would repeat every two weeks. Obviously, this would be very time consuming (and costly), so the only practical way to move teeth was with metal brackets and wires.

Since we use a computer simulation to move the teeth before making the aligners, we know from the start how long the treatment will be, and what the final results will look like. We like to have our patients participate in this part of the treatment so they can see what their final result will be and for their input if they have any particular goals in mind. To the right is an animated simulation of an Invisalign case.

The aligners must be worn at all times for the duration of treatment. The only time that they should be out is for eating and cleaning your teeth. Not following these guidelines will lengthen the treatment time because the teeth will not be moving as quickly as planned.

To enable the aligners to lock on tightly to the teeth, we place attachments on some teeth. Attachments are small, tooth-colored buttons which are bonded to teeth. They give the aligner something to "grab" onto and apply orthodontic force to the teeth. Attachments are also needed for certain types of movements. Teeth which need to be rotated or extruded need to have an attachment placed on them so the aligner can do its job.

How does Invisalign compare to traditional braces?

Invisalign and traditional braces are both categorized as orthodontic appliances because they both have the ability to move teeth in a controlled manner. Both Invisalign and traditional braces move teeth by applying force and pressure to the teeth, but they do it in different ways. Traditional braces move teeth by gluing a metal bracket to the teeth and using a wire to twist, pull and push the teeth to the desired location. Invisalign uses an aligner to apply force and pressure to the teeth. These two techniques both have their strengths and weaknesses. Simply stated, there are certain tooth movements which work better with Invisalign, and other tooth movements which work better with traditional braces. Many patients come to our office with the impression that Invisalign is less effective than traditional braces, which is not the case. There are situations where traditional braces are a better choice than Invisalign, but they only constitute a small percentage of the orthodontic cases we see.

An advantage of traditional braces is the fact that they are permanently fixed to the teeth during the duration of treatment which eliminates the patient compliance factor in treatment. People who are in Invisalign treatment and are not compliant in wearing their aligners as directed will not get their desired results. The ability for the patient to remove the aligners is what makes Invisalign so appealing to people, but it can also be a potential problem if the patient is not wearing them as directed. The removable aligners make it easy for people to clean their teeth, which can be quite difficult and time consuming for someone who has traditional braces. People wearing traditional braces can be at an increased risk for tooth decay and gum disease from the excessive food which gets caught in the braces.

How long does it take?

The length of an Invisalign case depends on how many teeth are being moved, and how much the teeth are moved. Many simple cases can be completed in less than six months, moderate cases in about twelve to eighteen months, and complex cases can require two years or more. It all depends on what we have to start with. One thing that people really like about Invisalign is that we know in the beginning how long the treatment will take because it is all done on a computer first. Being able to see how nice and straight the teeth are going to look gives people motivation to wear their aligners and stay on track of their treatment.

Do I need to see the dentist every two weeks?

No, you do not have to see the dentist every two weeks. Since all the aligners are made at the same time, we can give the patient several sets of aligners at once, and see the patient when needed. In some situations we can give the patient all of their aligners and really have no need to see them until they are done, and in other situations we may need to have the patient come in from time to time to monitor the movement of their teeth.

Here is a link to the patient education section of our website which you may find helpful. There is a lot of information there for you to browse through and to answer any questions you may have, and was designed by a dental education company whose tools are used in our office to help our patients understand their treatment options. Some of the information there may be a bit outdated because the dental field is always evolving, but the general concepts of dentistry are nicely described and illustrated.

Some of these pages require Adobe Acrobat to view them. If you do not have this installed on your computer, download and install it here for free.