We propose a computationally efficient, bio-mechanically relevant soft-tissue simulation method for cranio-maxillofacial (CMF) surgery. Special emphasis is given to comply with the current clinical workflow. A template-based facial muscle prediction was introduced to avoid laborious segmentation from medical images. In addition, transversely isotropic mass-tensor model (MTM) was applied to realize the directional behavior of facial muscles in short computation time. Finally, sliding contact was incorporated to mimic realistic boundary condition in error-sensitive regions. Mechanical simulation result was compared with commercial finite element software. And retrospective validation study with post-operative scan of four CMF cases was performed.
Most industrial laser applications utilize computer and robot assistance, for guidance, safety, repeatability, and precision. In contrast, medical applications using laser systems are mostly conducted manually. The advantages can be effective only when the system is coupled to a robotic guidance, as operating by hand does not reach the required accuracy. We currently developed the first laser osteotome which offers preoperative planning based on CT data, robot guidance, and a precise execution of the laser cuts. In an animal trial, our system was used to create a grid pattern of the same depth on the inner layer of parietal bone in 12 adult sheep. The same bone cuts were done with piezoelectric osteotome on the contralateral side. The micro-CT and histological analysis showed more new mineralized bone in the laser group compared to the piezoelectric group. As well, a cutting pattern with especially a constant osteotomy depth in the laser group was demonstrated. The here presented autonomous osteotomy tool shows not only an advantage in early bone healing stage but additionally sharp bone cuts with a very high accuracy and freely selectable design cuts.
We propose a computationally efficient and bio-mechanically relevant soft-tissue simulation method for cranio-maxillofacial (CMF) surgery. A template-based facial muscle reconstruction was introduced to minimize the efforts on preparing a patient-specific model. A transversely isotropic mass-tensor model (MTM) was adopted to realize the effect of directional property of facial muscles in reasonable computation time. Additionally, sliding contact around teeth and mucosa was considered for more realistic simulation. Retrospective validation study with postoperative scan of a real patient showed that there were considerable improvements in simulation accuracy by incorporating template-based facial muscle anatomy and sliding contact.
The interest about upper airway evaluation has increased lately. Therefore, many softwares have been developed aiming to improve and facilitate the analysis of airway volume. The objective of this study was to compare two different softwares packages, Mimics and Dolphin, in their accuracy and precision in upper airway space measurements. Preoperative cone beam computed tomography scans of nine nonsyndromic patients submitted to surgically assisted rapid maxillary expansion were included in this study. The imaging exams were converted to DICOM (digital imaging and communications in medicine) files and imported to the softwares. The mean volume for the Dolphin group (G1) was 10.791 cm3 (SD = 4.269 cm3) and for the Mimics group (G2) was 10.553 cm3 (SD = 4.564 cm3). There was no statistically significant difference between the two groups ( p = 0.105).
Diamond‐like carbon (DLC) has been established as a very favourable coating for joint prosthetics due to its low friction, high corrosion resistance and biocompatibility. The addition of dopants allows for the modification of several physical properties of DLC, whose relations to biocompatibility have not yet been thoroughly investigated. We studied the properties of a‐C:H layers deposited on TiAl6V4 by the plasma immersion ion implantation and deposition (PIII&D) technique. Physical analysis performed comprises the range of attainable compositions [obtained by Rutherford backscattering spectroscopy (RBS) and elastic recoil detection analysis (ERDA)] and structures [by Raman Spectroscopy and energy filtered transmission electron microscopy (EFTEM)] for the cases of the dopants N, Si and TiOx. The biocompatibility assessments were performed in vitro, utilizing human osteoblasts. Cellular proliferation was measured by means of DNA quantification. Osteogenic differentiation was investigated by screening alkaline phosphatase activity and mineralization of cultures. The results demonstrate that highly biocompatible and wear‐resistant coatings on complex formed implant surfaces can be efficiently fabricated utilizing PIII&D.
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