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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