Accuracy assessment of computer-aided three-dimensional simulation and navigation in orthognathic surgery (CASNOS)

Purpose: This study is aimed for measuring the accuracy of simulation and prediction of our CASNOS protocol in adult patients treated with 2-jaw orthognathic surgery. Methods: Adult patients with skeletal Class III malocclusions requiring 2-jaw orthognathic surgery were enrolled in the study. Three-dimensional imaging data of 1-month pre-surgical (T1) and 6-month post-surgical (T2) CT were compared to assess accuracy of CASNOS planning. The accuracy of CASNOS protocol was evaluated by calculating the differences in the positions of selected landmarks between simulated surgical and post-surgical 3D images parameters, including ANB, A-Nv, Pog-Nv, and the positions of selected landmarks (ANS, Point A, Point B, Pog) changes in horizontal (x-axis) and vertical (y-axis) directions. Overall geographical discrepancy of planning was assessed by superimposing the color mapping of T1 and T2 imaging. Results: Thirty adult patients with a mean age of 20.6 +/- 1.5 years (female/male = 18/12) were enrolled. The geographical changes of overall superimposition between the planned and post-surgical imaging was 0.60 +/- 10.19 mm (range: 0.42-1.08 mm). The discrepancies between simulated and post-surgical ANB, A-Nv, Pog-Nv were 1.16 +/- 0.36 degrees, 1.25 +/- 0.33 mm, 1.19 +/- 0.35 mm, respectively. The deviations between simulated and post-surgical Point A and Point B positions were within 1 mm in horizontal and vertical directions. Conclusion: The application of the pre-designed bony guiding splints of CASNOS protocol can allow surgeons to treat patients with craniofacial deformities precisely. CASNOS provides a novel approach for orthodontists and surgeons accurately remedying the patients with complex craniofacial discrepancies. Copyright (C) 2019, Formosan Medical Association. Published by Elsevier Taiwan LLC.