Orthodontic Aligners
Definition
[edit]Orthodontic aligners (also known as clear aligner therapy) are removable, transparent plastic devices used for the correction of Malocclusion. They serve as an aesthetic alternative to traditional metal or ceramic braces.
Mechanism of Action
[edit]Aligners work by applying light, continuous forces to the teeth.
- Incremental Movement: Each sequential aligner is fabricated to be slightly different from the previous one, moving teeth in increments of approximately 0.2 mm.
- Attachments: Also called "buttons," these are tooth-colored composite shapes bonded to specific teeth to assist the aligner in performing complex movements such as rotations or root torquing.
- Interproximal Reduction (IPR): In cases of crowding, a clinician may perform IPR (slenderizing) to create small amounts of space between teeth.
Workflow and Manufacturing
[edit]The fabrication process is a hallmark of modern digital dentistry:
- Digital Impression: An Intraoral scanner creates a high-precision 3D map of the dental arches.
- Staging: Clinicians use proprietary software to plan the biological movement of teeth in stages.
- 3D Printing: Models are printed for each stage of the treatment.
- Thermoforming: Thin sheets of medical-grade polyurethane (e.g., SmartTrack, Zendura) are molded over the 3D models.
Comparison with Fixed Appliances
[edit]| Feature | Clear Aligners | Fixed Braces |
|---|---|---|
| Aesthetics | Highly discreet | Visible (except lingual) |
| Removability | Removable by patient | Fixed |
| Hygiene | Easier (brush/floss normally) | Difficult (requires specialized tools) |
| Compliance | Highly dependent on patient | Not patient-dependent |
| Force Delivery | Intermittent (pushing) | Continuous (pulling) |
Clinical Complications
[edit]- Treatment Lag: Occurs when the biological movement of the teeth does not keep pace with the aligner sequence.
- Root Resorption: Though generally lower than fixed braces, excessive force can still lead to shortening of the tooth roots.
- Posterior Open Bite: A common side effect where the thickness of the plastic prevents the molars from touching properly at the end of treatment.