Braces are about 20-30% faster at moving teeth than Invisalign because Invisalign is a removable system. Braces are also the gold standard orthodontic treatment modality that can handle very simple or very complex cases. All new orthodontic treatments are compared with the standards set by fixed braces.
For the duration that the aligners are not in the mouth, the teeth can still drift away from the treatment position. When the aligners are put back on, the teeth are guided back into position by the aligners. This back and forth between periods of aligner wear vs aligner removal is what can slow down the movement of teeth. Also this is what introduces an element of unpredictability to removable braces, where the treatment outcome is not entirely under the dentist's control and patient compliance becomes extremely crucial to success.
For patients who demonstrate compliance and motivation, any brace system (fixed or removable, like Invisalign) can work just as well. Certain complex cases are best treated with fixed braces (for example, cases requiring extractions or jaw surgery).
Invisalign is useful in patients with a history of gum disease because access for cleaning and maintenance is easier and the forces are gentler than fixed braces. For patients with shortened roots or compromised teeth or implants, Invisalign can calibrate forces applied to individual teeth. This is the greatest advantage of Invisalign over fixed braces that move every tooth that is included in the brace set up, unless the tooth is anchored by a mini bone screw.
For patients who are unable to maintain a high standard of compliance, Invisalign can still work but the treatment tends to take longer (each aligner needs more time to work) and the final outcome needs a lot more finishing. I sometimes finish Invisalign cases with fixed braces if the patient does not want to have another round of Invisalign or if more detailed finishing is required.
Ultimately, fixed braces allows for greater control of tooth movement than Invisalign and patient compliance is removed from the list of variables that can affect a successful treatment outcome. The decision to choose Invisalign over fixed braces is something you and your dentist have to decide on together, based on your treatment needs and your preferences. Do not be afraid to ask frank questions during your consultation and treatment planning visits, because your dentist REALLY wants you to have a good treatment experience and finish your case nicely!
