Rotating is when you turn a tooth around its long axis. One method to rotate teeth is with the use of auxiliaries, such as buttons and elastics. One button is placed on the tooth to be rotated while another button is placed on an ‘anchor’ tooth. The goal is to provide rotational correction of a tooth without moving the anchor tooth.
A common strategy is to pit a tooth with less root surface area such as an incisor with that of a premolar or molar which has significantly more root surface area. If the aligner fits well and is worn as scheduled, there generally is no movement of the anchor tooth as the aligner keeps it in place. Alternatively, if there is great concern for anchorage loss or insufficient anchorage, the anchor button could be located on the aligner itself.
A note of caution: One must ensure that the tooth to be rotated actually ‘rotates’ around its long axis and is not moved mesially or distally into contact with the aligner or adjacent teeth preventing the desired rotation. Slowing down the velocity of the rotation movement may be well-advised.
- Resin Cement
- Composite resin for bonding orthodontic brackets
- Ceramic, metal, or plastic orthodontic button
- Light 3/16’ or ¼’ elastic
- Single-hole paper punch, aligner hole punch pliers
- Diamond or acrylic 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 a button on the tooth to be rotated by placing it off-center away from the direction it is to be rotated; bond a button on the anchor tooth, centered in the provided space.
- Ensure that there is adequate space to allow the tooth to rotate using the appropriate methods of IPR:
Modify the aligner(s)using a bur to remove small amounts of tray material that may interfere with the rotation.
- Appliance wear and elastic placement:
Insert tray and place the elastic over each of the facial buttons that you placed. A light 3/16" or 1/4" is commonly used depending on the distance between the two buttons. (See caution above)
The elastic is worn until the rotation is corrected or slightly overcorrected. Overcorrection can be planned in the treatment setup as well to prevent relapse. Carefully monitor the progress of the rotation at each appointment.
Rotational tooth correction can be performed using auxiliaries and provides another strategy for clinicians to treat more complex situations.