Assessment of simulated vs actual orthodontic tooth movement with a customized fixed lingual appliance using untreated posterior teeth for registration and digital superimposition: A retrospective study.

INTRODUCTION: With the advancement of computer-aided design and computer-aided manufacturing (CAD-CAM), digital setups that simulate the outcome of orthodontic treatment are frequently used. Incognito appliance system is a lingual orthodontic system that uses digital setups. A limitation to previous studies evaluating CAD-CAM simulated outcomes is the lack of stable reference points to superimpose on. The purpose of this study was to compare the simulated vs actual outcomes with the Incognito Lite appliance system. METHODS: Thirty-four final models were compared with their corresponding setup models exported from the Incognito Web site. Final surface 3-dimensional imaging software was used to digitally measure differences between the simulated and actual treatment outcomes using a digital registration and superimposition method that utilizes the unmoved posterior teeth as reference points. RESULTS: Differences between simulated and actual tooth movement were significant in the translational parameter, with a maximum average discrepancy in the maxillary central incisors of 1.0 +/- 0.6 mm (P <0.0001) and 0.8 +/- 0.4 mm (P <0.0001) for mandibular central incisors. Discrepancies between simulated and actual tooth movements decreased from anterior to posterior. The first bicuspids moved the least for both maxillary and mandibular teeth (range of 0.4 mm-0.7 mm). The differences for rotational parameters were statistically insignificant with a mesiodistal tip of 1.6 degrees -3.6 degrees , buccal-palatal torque 2.3 degrees -4.4 degrees and rotation around the tooth axis 2.3 degrees -5.0 degrees . CONCLUSIONS: Incognito Lite simulated tooth movements were achieved for rotation, tip, and torque (+/-3 degrees ). However, significant discrepancies were found between simulated and actual tooth position for translation (0.6-1.0 mm).