Extrusions are one of the most difficult movements to achieve with clear aligners. In previous posts, we've discussed a do-it-yourself technique for using a rubber band as an auxiliary. In that technique, you bond a ceramic bracket to the aligner, and a metal bracket to the tooth. You trim the aligner back to make room for the ceramic bracket, and run a 1/4" elastic band between the two brackets to apply force to the tooth.
Dr. Justin Anderson wrote in with a suggestion for improving the technique:
After having trouble getting a bracket to bond to the aligners, I changed to a different method and found better success. Trim back the aligner on the buccal and lingual. (In the original protocol they have you do this just on the lingual). Then bond the porcelain bracket to the tooth on the gingival most aspect of the buccal. Have the patient wear elastics from the bracket on the lingual over the aligner and back to the buccal bracket. This makes the elastics easier to place for the patient and there is less of a chance of de-bonding of brackets.
—Justin Anderson DDS
Thanks for the tip, Dr. Anderson! We're always glad to hear from providers.
We've also heard of doctors cutting two small slits in the aligner on the mesial and distal edges of a tooth and anchoring the elastic band on those slits—another way to avoid bonding the bracket to the aligner.
Whichever technique you use, make sure you trim a little extra so the bracket on the tooth has room to move when it is extruded.