Cutting Guide Accuracy in Computer-Assisted Mandibular Tumor Ablation

Abstract

Several pathological entities of the oral cavity require aggressive surgical intervention, including segmental mandibular resection. Appropriate preoperative planning and meticulous transfer of the planned surgery to the actual operative site are needed to ensure meeting the reconstruction goals, namely improving patient quality of life, and avoiding physical and social disabilities. Mandibular reconstruction is considered one of the most challenging and demanding procedures in the head and neck region. Fortunately, the introduction of computer-assisted surgery has had a tremendous positive impact on the surgical outcome's predictability. Compared to the traditional freehanded technique, CAD/CAM technology offers improved surgical outcomes, reduced operative time, and decreased flap ischemia time. Additionally, computer-assisted surgery allows for detailed planning of reconstructive hardware, such as determining the proper length, position, and angulation of screws (or in the case of immediate dental rehabilitation, dental implants). Despite the apparent advantages in computer-assisted surgery, some subjectivity of virtual planning is unavoidable as the manipulation is orchestrated by a surgeon and a bioengineer with no impeccable reconstruction target. It is essential to understand that every step has a potential for small error, which cumulatively leads to a more significant error in the final outcome. Several factors could affect the precise transfer of the virtual plan, such as appropriate placement and fit of cutting guides, orientation of the osteotomies, toughness and thickness of the saw blade, deformation of plates, surgeons' experience, and spatial relationship disparities. Although a few studies reported the xi i overall accuracy of fully guided computer-assisted mandibular reconstruction, no previous studies were dedicated to assessing the osteotomy line created by the 3D printed cutting guides. The accuracy of osteotomy lines has significant importance in surgical oncological management as it could potentially determine appropriateness of surgical margins. This study is designed as a retrospective cohort to examine the accuracy of the 3D printed cutting guide placement translated into the actual surgical cut. We also investigated the mandibular reconstruction's overall accuracy using a volumetric and morphometric assessment method compared to the virtually planned mandible. Fourteen patients met the criteria and were included in the final analysis. Data were collected to measure the mean deviation in the osteotomy line, the overall volume of the neomandible, and selected angular and linear distances.