A Postoperative Evaluation Guideline for Computer-Assisted Reconstruction of the Mandible

Abstract

Valid comparisons of postoperative accuracy results in computer-assisted reconstruction of the mandible are difficult due to heterogeneity in imaging modalities, mandibular defect classification, and evaluation methodologies between studies. This guideline uses a step-by-step approach guiding the process of imaging, classification of mandibular defects and volume assessment of three-dimensional (3D) models, after which a legitimized quantitative accuracy evaluation method can be performed between the postoperative clinical situation and the preoperative virtual plan. The condyles and the vertical and horizontal corners of the mandible are used as bony landmarks to define virtual lines in the computer-assisted surgery (CAS) software. Between these lines the axial, coronal, and both sagittal mandibular angles are calculated on both pre-and postoperative 3D models of the (neo)mandible and subsequently the deviations are calculated. By superimposing the postoperative 3D model to the preoperative virtually planned 3D model, which is fixed to the XYZ axis, the deviation between pre-and postoperative virtually planned dental implant positions can be calculated. This protocol continues and specifies an earlier publication of this evaluation guideline. Video Link The video component of this article can be found at https://www.jove.com/video/60363/ 6. Here, we present a practical, feasible and reproducible evaluation guideline for computer-assisted reconstructions of the mandible in order to create uniformity between studies regarding postoperative accuracy evaluation. This protocol continues and specifies an earlier publication of this evaluation guideline 7 , which is currently being tested in a large multicenter cohort study in which all different types of mandibular reconstructions will be analyzed for their accuracy aiming to discover tolerable outcome ranges regarding functionality.

Aesthetic Reconstruction of Onco-surgical Mandibular Defects Using Free Fibular Flap with and without CAD/CAM Customized Osteotomy Guide: A Randomized Controlled Clinical Trial

“…Nevertheless, standardization regarding the evaluation process is still a concern. In this study, standardization of the evaluation process was addressed and seems to be mostly in line with the Jove-published protocol by van Baar et al [23] in terms of imaging, machine and setting parameters, defects classi cation, using image-based 3D medical software, natural head position, and axis orientation. However, some steps were not exactly adherent to the Jove-published protocol, as our evaluation is based mainly on comparing the reconstructed mandible to the contralateral native mandible postoperatively.…”

Accuracy of Computer-Assisted Surgery in Maxillary Reconstruction: A Systematic Review

“…In the footsteps of our evaluation guideline for mandibular reconstruction using CAS [12,14], we will propose a practical, feasible, and reproducible evaluation guideline for maxillary and midface reconstructions using CAS in the future. This offers possibilities to study the influence of the parameters mentioned in Tables 1-3 on the postoperative accuracy results, which could provide more definitive evidence regarding the management of maxillary and midface defects.…”

“…However, uniformity in accuracy evaluation methods is lacking, and no evaluation guideline like the one previously published for mandibular reconstruction using CAS exists for maxillary reconstructions as of yet [12]. Similar to our previously published systematic review on accuracy in mandibular reconstruction [13,14], we reviewed all studies that quantitatively assessed the accuracy of maxillary reconstruction performed with CAS as mentioned above. Based on the accuracy results in the mandibular reconstruction, we hypothesize that the postoperative deviation of the bony segments of the flap remains within 5 mm compared with the preoperative virtual plan.…”

A Novel Treatment Concept for Advanced Stage Mandibular Osteoradionecrosis Combining Isodose Curve Visualization and Nerve Preservation: A Prospective Pilot Study

“…Imaging and Communications in Medicine (DICOM) files were uploaded in Mimics Medical 21.0 software (Materialise, Leuven, Belgium) and converted into 3D models using the thresholding tool; voxels with an HU above a selected threshold value are included in the ROI and transformed into 3D surface models in the Standard Tessellation Language (STL) file format ( 46 ).…”

“…Accuracy of the mandibular reconstruction was evaluated according to the evaluation method for computer-assisted surgery in mandibular reconstruction described by Van Baar et al ( 45 , 46 )..…”