Predictability of Orthodontic Tooth Movement With Invisalign Aligners

Together with the increased adult patient demand for orthodontic treatment and the push toward increasingly personalized treatment, technology developments have resulted in a growing worldwide demand for clear aligners, to the point that they are now an essential part of any orthodontic practice. Despite the widespread use of the technique, the existing literature about reliability of orthodontic tooth movement with Invisalign aligners seems not encouraging. Several papers have demonstrated that what is virtually planned is not what is clinically achievable. However, it should be considered that clear aligner orthodontics techniques are customized not only for the patients but for orthodontists too. Therefore, virtual treatment plan design, in terms of attachments' design and placement, orthodontic tooth movement (OTM) staging and aligner deformation overengineering, or in other words aligners biomechanics knowledge, plays a crucial role in defining the quality of the orthodontic treatment with Invisalign aligners. Based on these considerations the present study was designed to answer two research-clinical questions: 1) which are the less predictable orthodontic movements with Invisalign aligners when the treatment plan is designed by expert operators? and 2) which is the impact of the orthodontist experience, in terms of patient motivation, on the predictability of orthodontic tooth movement with Invisalign aligners? To answer those questions, the predictability of OTM in a sample of Invisalign patients treated by expert operators was compared with the predictability of OTM in a sample treated by post-graduate students. The null hypothesis for question 1 is that all the prescribed orthodontic tooth movements are predictable, while the null hypothesis for question 2 is that the reliability of orthodontic tooth movement is not affected by operator experience. 98 patients (31 M, 67 F; mean age 28 ± 12 years) were selected among those in treatment at the Department