Clear Aligners - "Rule of 3"
Use these rules to identify profitable, predictable cases and the estimated length of treatment.
Estimating Tx Duration:
√ Cases presenting 3 or less treatment goals depicted below can be completed in about 6-8 months. Always give a range!
√ Cases with 4 or more treatment goals depicted below, OR moderate anterior spacing/crowding up to 6mm, can be treated in about 12-14 months.
Pro Tip: Measure total spaces or crowding with a perio probe.
Treatment Goals
Midline Discrepancy -Total (Max of 1.5 mm of shift per arch)
Will need IPR and sufficient overjet to shift midlines
Overjet Reduction - Both Arches
Will need IPR on upper arch to reduce overjet
Overbite - Both Arches
Open Bite Reduction - Both Arches
Anterior open bites, only 1-2 mm closure can be done with high predictability.
Anterior Spacing - Per Arch
Anterior Crowding - Per Arch
Crossbite - Per Teeth
Contraindications for Dandy clear aligner case election
No Class III Cases
Mutilated Dentition
Lack of posterior support and appropriate anchorage units, loss of vertical dimension, presence of fixed or removable prosthesis, endodontic involvement, and compromised periodontal condition all contribute to the complexity. In order to move anterior teeth, there needs to exist stable posterior teeth to be used for anchorage. Multiple bridges, restorations, or missing teeth all contribute to a reduction in anchorage and therefore a less predictable outcome.
Impacted Teeth
Impacted teeth could cause root resorption, require surgical intervention to expose and bring into the arch, or extraction with a compromise final occlusion.
Transitional Dentition
Children and adolescents in transitional dentition need special consideration for timing of eruption and facial growth. Lack of posterior anchorage during transition, newly erupting anterior or posterior teeth, ectopic eruptions, eruption cysts, all contribute to the complexity.
Ectopic teeth
These teeth require special auxillaries, extractions, and periodontal conditions to appropriately manage.
