THE USE OF 3D VIRTUAL PLANNING AND 3D PRINTING FOR THE TREATMENT OF FACIAL ASYMMETRY: A CASE REPORT
2.1. Preoperative planning Preoperative imaging was performed with a 128-slice spiral multi-slice computer tomography( MSCT) scanner( Siemens Somatom Definition Flash, Germany: 120 kV, 161 mAS, slice thickness 0.75 mm). The Digital Imaging and Communications in Medicine( DICOM) images of the patient were imported into the Simplant O & O software( Materialise Dental, Leuven, Belgium) and the mandible, maxilla, skull and soft tissue were segmented via thresholding( Fig. 1a). A mirroring procedure of the mandible was implemented around the midsagittal plane as defined by Gateno et al.( 3)( Fig. 1b). The left side
was mirrored to the right and the right was mirrored to the left( Fig. 1c and 1d). As shown in figure 1, the mirroring from left to right wasn’ t feasible since the mandibular alveolar nerve would be exposed, therefore, only the mirroring of the right to the left was considered. This option concerns an augmentation procedure( Fig. 1c). Afterwards the original mandible was subtracted from the mirrored mandible at the left side( Fig. 1e) and exported as STereoLithography( STL) file then 3D printed in polymer material using Objet Connex 350( Stratasys, Eden Prairie, Minnesota, USA) with slice thickness of 0.03 mm.
a. b. c.
d. e.
Figure 1. a. Preoperative skull. b. Preoperative skull with mirrored mandible. c. Preoperative skull with mirrored mandible right to left. d. Preoperative skull with mirrored mandible left to right. e. Preoperative skull with mirrored mandible right to left subtracted
This subtracted object served as a surgical guide for the bone graft size and shape during the operation( Fig. 2). This object was sterilized prior to the operation. The results of the mirroring and the expected soft tissue simulation were shown to the patient prior to the operation( Fig. 7 a, b). The patient accepted these simulations and the fact that the postoperative results may differ from the simulations.
a. b.
Figure 2. a. The surgical guide in STL format( dimensions: 29.6mm x 89.2mm). b. The same object in the operation room after 3D printing and sterilization
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