Development of a simulation system in mandibular orthognathic surgery based on integrated three-dimensional data

Abstract

PurposeSurgical simulation should reflect the 3D movement of dentition and the resultant movement of the osteotomized segments, which can influence surgical outcome. The present study was aimed at developing a new simulation system that enables virtual osteotomy of a given surgical situation and evaluation of the bony interference between the osteotomized segments of the mandible.Subjects and methodsThe data of 3D computer tomography (CT) for maxillomandibular dental casts were integrated into the standard coordinates of a 3D cephalogram. To evaluate the accuracy of the system, measurement errors of the 3D CT virtual model from a dry skull were compared with the computer simulation system and a contact-type 3D digitizer. To examine the clinical accessibility, 15 mandibular prognathism patients with mild to severe asymmetry were evaluated with the simulation program.ResultsThe average error of measurement in all directions was 1.31 mm. It was possible to simulate various osteotomy procedures by conversion of the 3D coordinates of the dental cast and CT data into the standard coordinate system of a 3D cephalogram. Using this simulation system, it was possible to prevent condylar torque or segment malpositioning by removing the bony interference visualized by a 3D virtual model.ConclusionA new system, which enables the precise visualization of osteotomized segments and calculation of bony interference, was proposed in the present study. This new system provides an acceptable precision of treatment planning of orthognathic surgery, especially for facial asymmetry.

Computer-Assisted Orthognathic Surgery for Patients with Cleft Lip/Palate: From Traditional Planning to Three-Dimensional Surgical Simulation

“…Drawbacks of 2D planning for mandibular positioning show up in 3D simulation after treatment plan transfer. Osseous collisions or gaps in the BSSO segments and the need of bone grafting are reliably detected in 3D simulation [ 41 ], making the ramus area adjustments predictable in terms of lower face symmetry. This finding is regularly missed in 2D cephalograms (Figs 3H and 4H ), but easily corrected in the 3D basal view (Figs 3L and 4L ).…”

Comparative Study of Mandible Ramus Morphology Using 3-dimensional CT in Sagittal Split Ramus Osteotomy

“…Multiple regression analysis was performed for each class using each measurement value from the 3D CT images as a dependent variable and facial angle, Y-axis, SNA, SNB, angle between the maxilla and the mandible (ANB), gonial angle, overjet, and overbite as independent variables. [7], IS: position of mandibular inferior border at second molar [8], CF: position of mandibular canal at first molar [9], CS: position of mandibular canal at second molar [10], BF: position of buccal cortical bone at first molar [11], BS: position of buccal cortical bone at second molar [12].…”

“…Approximately 650 surgical procedures are performed under general anesthesia at our hospital each year, and about 120 of these (18%) are sagittal split ramus osteotomies. This technique sometimes results in nerve damage, abnormal bone fracture, or other adverse events 11,22) . These accidents are thought to be associated with skeletal abnormalities.…”

Transversal Width of Mandibular Bone and Neurosensory Disturbance after Bilateral Sagittal Splitting Ramus Osteotomy

“…The introduction of X-ray CT has enabled a more detailed examination of mandibular morphology and structure, allowing surgeons to accurately determine the shape and internal structure of the mandible before operating. New developments in such technology have also allowed treatment plans to benefit from software-assisted 3-dimensional imaging [14], leading to improvements in both quality and safety of medical care. In particular, identifying the internal structure of mandibular cancellous bone is crucial in establishing the safety of BSSRO because this procedure requires the ramus to be split while avoiding injury to the inferior alveolar nerve or inferior alveolar vein running through the mandibular canal [15].…”