With traditional braces, elastic traction, such as class II corrections, can effect tooth movement. Examples of this are; molar extrusion, advancement of the lower anteriors, and some distalization of the upper posterior quadrants.
The paradigm is different when elastics are used with clear aligners; because the teeth are encased in the plastic, the elastics really cannot effect any tooth movement (that happens with the staging of the aligners). The horizontal corrections we see are a result of the arch movement and/or the repositioning of the mandible. This is true whether the elastics are worn on buttons attached to the teeth or to slits cut into the aligners. This is an important paradigm to understand if you want to use elastic traction with clear aligner treatment.
Elastics on buttons attached to teeth Elastics on slits cut into the aligners
Not uncommonly, a doctor will design an aligner treatment plan to correct a malocclusion with a horizontal imbalance, i.e. class II or class III. A ‘dental’ class II correction could possibly be made by distally rotating the upper first molar or distalizing the upper molars into a class I relationship. If a ‘skeletal’ class II or III correction is desired, heavier orthopedic forces, i.e. elastic traction or some other mechanical device (or orthognathic surgery), will need to be considered.
If elastic traction is selected to be used with aligner treatment, the resulting horizontal change will either be a slight, if any, remodeling of the alveolar process holding the teeth en masse, or a repositioning of the mandible; any concurrent tooth movement will be staged by the setup technician and accomplished by compliant wear by the patient. ACS was designed to simulate the dental arch or skeletal changes anticipated to be made by the patient’s compliant wear of elastics.
Example: Class II, patient's actual articulation
ACS, requested by the doctor using elastic traction, will direct the technician to articulate the digital models according to the doctor’s prescribed correction goals prior to any tooth movement, which then allows the technician to appropriately reposition the anterior teeth in harmony with the posterior occlusion. Similar alternative techniques perform the horizontal shift, or ‘jump’, of the models after all of the tooth movement has been accomplished.
Example: ACS, per doctor's Rx, post staging by technician
How to request ACS
To request arch correction simulation, include this statement in the Additional Instructions section of your case submission form, filling in the molar relationship you want to see in the setup (Class I, Class II, etc.):
Simulate arch correction to a molar relationship of ______ on the left and ______ on the right. I understand that I am responsible for any auxiliary techniques necessary to achieve this relationship.
Make sure you include the entire statement. Your submissions may be delayed if you don't include the disclaimer at the end. Here's an example:
If you have any questions about ACS you can contact ClearCorrect Provider Services who will be happy to assist.