The use of elastics to correct Class II dental malocclusion can be reasonably effective with clear aligner treatment, assuming, of course, that the patient is fully compliant in wearing the elastics as directed by the treating doctor.
There are two ways class II elastics can be used with aligners, each with their own pros and cons.
#1 - Elastics are attached to the aligner via "cut outs" in each aligner
- Class II cut outs made at the time of aligner fabrication
- No aligner modification needed by Doctor or staff, saves personnel time
- No bracket visible on the cuspids
- Elastic in cut outs may distort aligner away from the teeth
- Elastic may dislodge the aligner off of the teeth; when aligners do not fit tightly to the tooth, movement effectiveness is reduced
- Cut outs may exist in the aligner beyond the need for elastics
- Elastic cut outs may cause tissue irritation
- Some elastic force wasted as the aligner is pulled against the front teeth, not the posterior quadrants
#2 - Elastics attached directly to the teeth via buttons
- Aligners are modified only for elastic wear, instead of having the cut outs on every aligner throughout treatment
- Elastic force applied to the teeth (or alveolar bone if using TADs) is more effective than pulling on the aligners, which may cause them to unseat or distort
- Staff must modify each aligner, but this only takes seconds, not minutes
- Buttons are on the teeth until class II correction is complete
Following is a method of class II correction using buttons attached to the teeth.
- Resin cement
- Composite resin for bonding
- Ceramic or plastic orthodontic bracket
- Elastic band
- Single-hole paper punch, aligner hole punch plier, acrylic or diamond bur
- Modify the aligner(s) to prepare for bonding of the buttons:
Using a single-hole paper punch, aligner hole punch plier, acrylic or diamond bur, remove a semi-circular area of the aligner’s gingival margin where a button is to be placed.
- Tooth preparation using conventional etch and bonding protocols:
Etch the area on the teeth where the buttons will be placed. Rinse the acid and dry with the air/water syringe.
- Button placement:
Bond the buttons to the teeth where you etched in step 2 above. Place the button near the mesiofacial gingival margin.
- Elastic placement:
Insert aligner and stretch the elastic between the facial buttons that you placed on the cuspid and molar.
- Carefully monitor the progress of the correction at each appointment
The elastic is worn until the class II (or class III) is corrected or slightly overcorrected. Overcorrection can be planned in the treatment setup as well to prevent relapse.