A summary of: Galan-Lopez, L., Barcia-Gonzalez, J. and Plasencia, E. (2019) A systematic review of the accuracy and efficiency of dental movements with Invisalign®. The Korean Journal of Orthodontics, 49(3), p. 140. Available at: https://doi.org/10.4p41/kjod.2019.49.3.140
In conventional orthodontic treatment, the use of braces can cause patient discomfort and interfere with aesthetics. With significant recent improvements in computer-aided design/computer-aided (CAD/CAM) manufacturing and dental materials, there has been an increased demand for plastic systems and individualized orthodontic treatments.
Initially, the focus of the Invisalign® system was to close small spaces and solve low and moderate crowding. However, ongoing research and development has allowed treatment of more complex malocclusions. It is currently one of the most used systems among the aligners.
Invisalign® asserts that it can resolve:
- Rotations of 40° in upper and lower central incisors, 45° in canines and premolars, 30° in lateral incisors, and 20° in molars.
- Extrusions and intrusions of 2.5 mm in anterior teeth and radicular movements of 4 mm and 2 mm in posterior teeth.
This study investigated the available scientific evidence in literature to assess whether the Invisalign® system exhibits similar effectiveness to that of conventional orthodontics.
Materials & Methods:
A search strategy was used to identify articles that referenced Invisalign® published between August 2007 and August 2017 in the following databases: MEDLINE, Embase, Cochrane Library, Web of Knowledge, Google Scholar, and LILACS. A manual search of clinical trials was also performed in scientific journals and other databases. 5 articles were excluded due to excess bias and 20 articles were selected.
Figure 1 – PRISMA diagram
Results & findings:
- Invisalign® AND fixed appliances are able to alter intercanine, interpremolar, and intermolar width in the presence of crowding.
- The majority of tooth movement occurs during the first week with plastic systems.
- Durations of treatment varied according to the degree of crowding:
- ~13 months (mild)
- ~16 months (moderate)
- ~18 months (severe)
- A randomized controlled trial found that treatment time is longer with Invisalign® than with brackets.
- The accuracy of movement with Invisalign® was 55% to 72% and reportedly dependent on how often the aligner was changed.
- Vertical movement and derotation are difficult movements to accomplish with aligners.
- Overbite was the most difficult parameter to predict and correct with aligners. In general, 1.5mm can easily be resolved.
- Buccolingual inclination and occlusal contacts are worse with Invisalign®.
- Overcorrecting with Invisalign® is recommended as there is better root control with fixed appliances.
- Sex and age affect tooth movement in both systems.
In recent years, the precision of movement and correction with Invisalign® has improved exponentially, reaching values of 70% to 80%. However, it has been proven that brackets remain more accurate than plastic systems.
The level of evidence was high. Although it is possible to treat malocclusions with plastic systems, the results are not as accurate as that of fixed appliances.
Research Summary Written by: Aisha Azlan, BDS 2 – University of Manchester