A frequent question I am asked by patients is “How is this aligner going to straighten my teeth?” Usually they are holding up a single aligner with a bewildered and/or cynical look on their face! I then smile, and explain that it is a sequence of several aligners custom made for each individual that accomplishes this goal.
Teeth are moved as a result of physiologic forces being applied in a given desired direction. It doesn’t matter whether these forces are applied as the “pull” of archwires (braces) or the “push” of aligners (Invisalign). While there are a few movements that the pull of archwires can biomechanically accomplish better than Invisalign – such as eruption of an impacted tooth, there are many more movements that Invisalign can perform better due to the infinite number of tooth contacts.
With braces, the flex of the distorted wire as it returns to its original position is the force generated to move the teeth. When Invisalign is used, the force needed to move the teeth is generated by the flex of the resilient plastic over the teeth. Just as with wires, each tray can only move the teeth a predetermined amount and speed based on physiologic bone remodeling needed, nerve and blood vessel migration, etc. So, the further the teeth need to move the greater the number of trays needed.
Thus, at the beginning, your teeth are at position 0. Your teeth are moved in the desired direction a predetermined amount by the computer, and tray #1 is made. When the trays are delivered, you receive tray #1. This will “Flex around your teeth that are currently in position 0. The rebound force in the trays will move the teeth to position #1 as the tray “relaxes”. One to two weeks later, you place tray #2, which now flexes around your teeth that have been moved from position 0 to 1 and they now are moved to position 2. You will then receive tray #3 and this process is repeated through the sequence of trays until the teeth have made all the movements prescribed by the doctor.
The beauty of this system is as long as the trays are fitting properly through the progression, the teeth must move (or the trays wouldn’t be fitting). For this reason, the patient is responsible for the proper amount of wear, and the progression through the sequence cannot proceed faster than the physiologic ability of the teeth to move.
When it comes to correcting the bite, the same rules apply to Invisalign as with braces. Basically, braces and wires straighten the teeth, just as the sequence of aligners do with Invisalign. However, elastic wear, expanders, and other means used to correct the bites with braces can and should be used with Invisalign to provide optimal results.
For questions or comments, we welcome you to contact our office. As an Elite provider of Invisalign we can assure you our experience will aid us in providing the best care possible.