Objectives: To present seven orthodontic cases treated using the Invisalign First system (Align Technology, San Jose, CA, USA), showing the discrepancy between the maxillary width expansion achieved in the canine and first molar regions using Invisalign First and the expansion simulated in the ClinCheck planning software in the same areas, and suggest-ing potential improvements to the ClinCheck plan when per-forming expansion with Invisalign First.
Materials and methods: Seven patients treated with Invis-align First were evaluated retrospectively. The patients’ ClinCheck models, which simulated the situation of the final aligners, and their scan-based models representing the same final aligners were compared. The intercanine and intermolar width discrepancies for both models were summarised in tables.
Results: Six out of the seven patient cases indicated that the effectiveness of Invisalign First for achieving the planned transverse expansion width when treating patients seems to be greater in the canine region than in the first molars, creat-ing the appearance of a broad smile due to small buccal corridors.
Conclusion: These results suggest that future ClinCheck simu-lations should be adapted by avoiding overcorrection during expansion in the intercanine area to compensate for the in-creased expansion achieved in this region compared to that obtained in the first molar region.