scholarly journals Predictability of maxillary positioning: a 3D comparison of virtual and conventional orthognathic surgery planning

2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Anja Quast ◽  
Petra Santander ◽  
Timon Kahlmeier ◽  
Norman Moser ◽  
Henning Schliephake ◽  
...  

Abstract Background Virtual surgery planning (VSP) is believed to reduce inaccuracies in maxillary positioning compared to conventional surgery planning (CSP) due to the elimination of face-bow transfer and laboratory steps. However, there is still a lack of comparative studies for the accuracy of splint-based maxillary positioning in CSP versus VSP. Therefore, the objective of this retrospective, observational study was to compare if splints produced by VSP and CSP reach postoperative outcomes within clinically acceptable limits. Methods The planned and actual postoperative results of 52 patients (VSP: n = 26; CSP: n = 26) with a mean age of 24.4 ± 6.2 years were investigated by three-dimensional (3D) alignment with planning software. The conventional treatment plan was digitized, so that the evaluation of both methods was performed in the same manner using the same coordinate system. Inaccuracies were measured by sagittal, vertical and transversal deviations of the upper central incisors and the inclination of the maxillary occlusal plane between the planned and achieved maxillary positions. Results Both methods demonstrated significant differences between the planned and actual outcome. The highest inaccuracies were observed in vertical impaction and midline correction. No significant differences between CSP and VSP were observed in any dimension. Errors in vertical and sagittal dimension intensified each other. Conclusions In conclusion, splint-based surgeries reached similar results regardless of the applied planning method and splint production.

Author(s):  
Johanna Nilsson ◽  
Fredrik Nysjö ◽  
Ingela Nyström ◽  
Johan Kämpe ◽  
Andreas Thor

Abstract Purpose The management of complex mandible fractures, i.e. severely comminuted or fractures of edentulous/atrophic mandibles, can be challenging. This is due to the three-dimensional loss of bone, which limits the possibility for accurate anatomic reduction. Virtual surgery planning (VSP) can provide improved accuracy and shorter operating times, but is often not employed for trauma cases because of time constraints and complex user interfaces limited to two-dimensional interaction with three-dimensional data. Methods In this study, we evaluate the accuracy, precision, and time efficiency of the haptic assisted surgery planning system (HASP), an in-house VSP system that supports stereo graphics, six degrees-of-freedom input, and haptics to improve the surgical planning. Three operators performed planning in HASP on computed tomography (CT) and cone beam computed tomography (CBCT) images of a plastic skull model and on twelve retrospective cases with complex mandible fractures. Results The results show an accuracy and reproducibility of less than 2 mm when using HASP for virtual fracture reduction, with an average planning time of 15 min including time for segmentation in the software BoneSplit. Conclusion This study presents an in-house haptic assisted planning tool for cranio-maxillofacial surgery with high usability that can be used for preoperative planning and evaluation of complex mandible fractures.


2017 ◽  
Vol 28 (2) ◽  
pp. e173-e175 ◽  
Author(s):  
Nathalie Pham Dang ◽  
Agathe Lafarge ◽  
Arnaud Depeyre ◽  
Laurent Devoize ◽  
Isabelle Barthélémy

Author(s):  
Christopher L. Lee ◽  
Max C. Dietrich ◽  
Uma G. Desai ◽  
Ankur Das ◽  
Suhong Yu ◽  
...  

This paper presents the design evolution, fabrication, and testing of a novel patient and organ-specific, three-dimensional (3D)-printed phantom for external beam radiation therapy (EBRT) of prostate cancer. In contrast to those found in current practice, this phantom can be used to plan and validate treatment tailored to an individual patient. It contains a model of the prostate gland with a dominant intraprostatic lesion (DIL), seminal vesicles, urethra, ejaculatory duct, neurovascular bundles, rectal wall, and penile bulb generated from a series of combined T2-weighted/dynamic contrast-enhanced magnetic resonance (MR) images. The iterative process for designing the phantom based on user interaction and evaluation is described. Using the CyberKnife System at Boston Medical Center, a treatment plan was successfully created and delivered. Dosage delivery results were validated through gamma index calculations based on radiochromic film measurements which yielded a 99.8% passing rate. This phantom is a demonstration of a methodology for incorporating high-contrast MR imaging into computed-tomography-based radiotherapy treatment planning; moreover, it can be used to perform quality assurance (QA).


2019 ◽  
Vol S (1) ◽  
pp. 11-14
Author(s):  
Lamiaa A. Hasan ◽  
◽  
Nada M. Al-Sayagh ◽  
Lara R. Al-Banaa ◽  
◽  
...  

Objective: The objective of this study was to evaluate the biomechanical effect of mandibular corpus distraction osteogenesis with different orientations and rates. Materials and Methods: A three-dimensional model of the mandible was created. The vertical surgical cut was made, the force was applied horizontally in a bidirectional manner within two orientations: parallel to the occlusal plane and parallel to the inferior border of the mandible with three rates (0.5mm, 1mm and 1.5mm). Results: The maximum values for von Mises stress when the force was applied parallel to the inferior border of the mandible with all three rates were smaller than those with force direction parallel to the occlusal plane. The displacement in all three directions x, y, and z were not parallel and prominent in the anterior part of the mandible, while the movement at the posterior part is negligible, x and z displacement were bigger when force was applied parallel to the inferior border of the mandible, z displacement was more prominent than x and y displacement, both directions produced upward rotation of the mandible, this rotation was more noticeable when the force was applied parallel to the inferior border of the mandible. Conclusions: A vertical cut can be used in the patient with a long anterior face. This site of distraction achieves more lengthening of mandible than expansion.


1999 ◽  
Author(s):  
Takeo Asano ◽  
Hiroshi Matsuzaki ◽  
Akito Saito ◽  
Yukihiko Furuhashi ◽  
Yuichiro Akatsuka ◽  
...  

Abstract Practical use of medical simulation system with virtual reality technology is expected because of the learning of the operation procedure. We have therefore developed a neurosurgical simulation system for minimally invasive surgery. Our system is composed of PC and one or two haptic interfaces. Operator can pick up the region of interest to specify the disease portion from DICOM format image data, then three-dimensional model have made by volume and surface rendering with this data. In the next step, system estimates and indicates on CRT the minimally invasive path from the head surface to the disease target that was picked up beforehand by this system which retains healthy human’s three-dimensional atlas data. Finally, the operator can perform a virtual surgery operation by the haptic interface that has been connected to PC, and can cut off an exact or approximate portion of the disease. The operator can feel the resistance from this virtual object. This operation process can be recorded for medical doctors to review later.


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