Age in itself is not a limitation for orthodontic tooth movement. Rather it is the health of the periodontium that is more important.
Today's understanding of the capabilities of clear aligner corrections allows experienced clinicians to treat young patients in their deciduous and late mixed dentitions with clear aligners. The clinician must know how to manage the loss of deciduous teeth and the eruption of permanent teeth before attempting treatment for a younger patient.
Treatment at this age should be approached carefully as eruptive movements will cause aligner fit issues.
Some older patients need to be reminded that metabolism, healing and tooth movement are slower relative to a younger person.
In addition, the rate of tooth movement is highly variable and one cannot "guarantee" that treatment will proceed at a specific rate.
Older patients generally have more dental work relative to a younger patient. The dental work includes crowns, root canals, veneers and other restorations. For the most part, these items are not a contraindication for tooth movement but the patient, as part of the pre-treatment informed consent, needs to be advised that during orthodontic treatment, one or more restorations may need to be adjusted, repaired, or replaced to be in accord with the new occlusion.
Lastly, older patients have more wear and tear on their dentition. Often there is uneven incisal edge wear, worn cusp tips, tooth chipping, craze lines and tooth discoloration. It would be prudent to identify these issues in advance and let the patient know that restorative dentistry has a number of solutions for these issues and these treatments can be coordinated with orthodontics as a comprehensive treatment plan to restore and rejuvenate their smile.
If you are treating an older patient with clear aligners please be sure to make them aware of the above information prior to starting treatment.