Efficacy of Anterior Tooth Simulations with Clear Aligner Therapy - A Retrospective Cohort study of Invisalign and Flash Aligner Systems

Hanadi Sorour1, Dhaval Fadia2, Donald J. Ferguson3, Laith Makki1, Samar Adel4, Ismaeel Hansa5, *, Nikhilesh R. Vaid2
1 Private Practice, Abu Dhabi, UAE
2 Department of Orthodontics, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Chennai, India
3 Department of Orthodontics, European University College, Dubai, UAE
4 Department of Orthodontics, Faculty of Dentistry, Alexandria University, Alexandria, Egypt
5 Private Practice, Durban, South Africa

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© 2022 Sorour et al.

open-access license: This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

* Address correspondence to this author at the Private Practice, Durban, South Africa; E-mail:



The purpose of this study was to compare the efficacy of tooth movement between two clear aligner systems by comparing the predicted treatment outcomes versus actual outcomes achieved using a 3D best-fit algorithm.

Materials & Methods:

Clear aligner therapy (CAT) was used to treat 62 patients; n=38 Invisalign® and n=24 Flash®. The Invisalign group had a male to female distribution of 13:25 and a mean age of 35.5, while the Flash group had a male to female distribution of 6:18, with a mean age of 29.2. Differences in predicted versus achieved actual outcomes were compared using eModel Compare 8.1 software.


1) Intra-group differences between predicted and achieved tooth movements for angular movements were statistically (P<0.05) and clinically (>2°) significant with both treatment methods, except for tipping of maxillary and mandibular incisors for Flash® (<2◦). 2) Inter-group results demonstrated statistically significant differences in favor of Flash® for maxillary central incisor Tip (1.3°), BL movements for maxillary canines (0.1mm), and mandibular central incisor Rotations (1°). These did not exceed the threshold for the clinical relevance of 2° or 0.5mm.


There were no differences in clinical accuracy and efficacy between Invisalign or Flash aligner systems in achieving predicted tooth movement.

Keywords: Clear aligners, Invisalign, Flash, Digital orthodontics, Efficacy, Tooth simulations.