Digital treatment planning and clear aligner therapy: A retrospective cohort study.

Objective: To investigate the total number of digital treatment plan (DTPs) and aligners manufactured for clear aligner therapy (CAT) by Invisalign^® from initial treatment planning to the completion of CAT.

Design: A retrospective cohort study.

Material and methods: A total of 30 patients, from each of 11 experienced orthodontists, who commenced treatment over a 12-month period, were assessed regarding the number of DTPs and aligners prescribed from initial planning to completion of CAT. Patients were categorised according to the number of aligners prescribed by the initial DTP into mild (<15), moderate (15-29) or severe (>29).

Results: After the application of inclusion/exclusion criteria, 324 patients (71.9% women; median age = 28.5 years) undergoing non-extraction treatment with the Invisalign^® appliance were assessed. The median number of initial DTPs was 3 (interquartile range [IQR] = 2, 1-9) per patient before acceptance by the orthodontist. Most (99.4%) patients required a refinement phase with a median of 2 (IQR = 2, 2-7) refinement plans recorded. A total of 9135 aligners per dental arch, was prescribed in the initial DTP of the 324 patients assessed and 8452 in the refinement phase. The median number of aligners per dental arch prescribed from the initial DTP was 26 (IQR = 12, 6-78) and from the refinement plans was 20.5 (IQR = 17, 0-132).

Conclusion: A median of three initial DTPs and two refinement plans were required for patients undergoing non-extraction treatment with the Invisalign^® appliance. Patients were prescribed almost double the number of aligners initially predicted to manage their malocclusion.