AO CMF Start-up Grants
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AO CMF Start-up Grant Funded Research Projects
The abstracts of the latest funded projects under the start-up grant
AO CMFS-17-15D Project title: Creation and validation of a 3D cephalometric software based on Delaire’s analysis
There is a large number of cephalometric analyzes, based on the analysis of facial points or based on radiology analyzes. Nowadays new technologies allow us to catch and analyze patients’ faces (thanks to 3D photography) and to get simple access to head CT-scans. Under those circumstances, our cephalometric analyzes should evolve in order to adapt to these features.
There has already been attempts to create 3D cephalometric analyzes based on CT-scans, but none of them were based on a dedicated software. Therefore results were impossible to reproduce. We propose to create a 3D cephalometric analysis free software for research based on CT-scans DICOM files, easy to use and available for everyone.
Our first step after the creation of the software is to plan a comparative study between “classic” radiography analysis and 3D analysis, on a cohort of 100 to 150 patients with a point to point comparison, to show that the 3D analysis is theoriticaly at least as good as the classical radiographic one.
The advantages of this new technology would be a greater precision in cephalometric outline, and so in the analysis of the patient facial lines. By analyzing a 3D volume we also intend to answer some multi-dimensional questions about the chin position, mandibular asymmetry and other complex facial skull movements.
AO CMFS-17-20K Project title: Fully MRI based 3D virtual planning of CMF tumour resection and free flap reconstruction
The aim of the proposed clinical study is to change the conventional CT-based 3D virtual planning workflow for CMF tumors by developing a method for MRI-based tumor resection as well as free flap reconstructive planning. In addition the MRI-based workflow is complemented with the quantification of vascular flow in both donor and recipient site, as well as the 3D visualization of perforators. Project description: Multiple types of MRI sequences will be studied for visualizing bone and vascularization. Several MRI- sequences are known to be suitable for segmenting bone for 3D planning, these will be explored within this project. Also MR-Angiogram with flow measurements will be selected for visualizing arteries and to quantify the arterial flow, thereby determining suitability for transplantation. A workflow for MRI-based 3D surgical planning with bone cutting guides will be developed using a four-step approach. Key MRI parameters are defined (phase 1), followed by an application of selected bone and Phase Contrast-MRI sequences on healthy volunteers (phase 2).The most suitable (bone and Phase Contrast) MRI sequences will be chosen for phase 3. These protocols are validated by applying them on patients (n=10) and comparison to corresponding patients CT data, which is the gold standard. The mean deviation values between the MRI- and the CT-based models are determined by 3D comparison analysis as a primary outcome measure.Already for validation of Black Bone sequences approval has been obtained from the local medicalethical board (file number M16.198347).
Phase 4 entails examination of the clinical value during surgery and in pre-op clinical decision making,using bone cutting guides (for mandible/maxilla and fibula) designed from MRI-based models, inpatients with oral cancer who will undergo surgical treatment with free flap reconstruction. Secondary outcome measures are 1) the deviation of the actual bone cutting planes in the CMF region as well asat the bone-free flap, compared to the 3D planning and 2) the fit of the guides to the bone surface. The final result of this project is aimed to be a complete MRI based 3D virtual planning workflow including resection of the tumor and free flap reconstruction planning.
Optimisation of three-dimensional lower jaw resection margin planning using a novel Black Bone magnetic resonance imaging protocol.
PLoS One. 2018 Apr 20;13(4):e0196059. doi: 10.1371/journal.pone.0196059. eCollection 2018.
AO CMFS-18-02M Project title: CTRead - A revolutionary approach to training residents in CT Facial Bones interpretation
Facial trauma is a common occurrence worldwide which can lead to a plethora of functional, cosmetic, and emotional sequelae. Proper diagnosis of the direction, extent, and displacement of facial fractures by oral surgeons using the gold standard high-resolution CT scanning is imperative to improve patient outcomes and avoid unnecessary complications. Despite the importance of accurate diagnosis, oral surgery residents often receive a variable level of CT interpretation training from a senior resident or staff in an unstructured manner. To address this inconsistency in training, this project aims to create a standardized, scalable training module called CTRead for new residents in oral and maxillofacial surgery everywhere so that they can become competent and confident when interpreting scans and presenting them to their senior residents and staff. CTRead will be a web based training module which will take a student, resident, or even staff member through the reading of a CT Facial Bones scan one step at a time. Users will be shown normal CT scans, taught how to interpret anatomy, and then taught how to identify common fractures in facial trauma patients. To test the effectiveness of CTRead, participants’ confidence level and actual interpretation skill will be assessed via a mandatory short but comprehensive survey and marked CT interpretation quiz at the beginning and end of the training module. This will allow us to gather key information users’ confidence in interpreting CT scans, and their ability to accurately diagnose traumatic fractures as they progress through the module. It is hoped that completion of CTRead will lead to a significant increase in both confidence level and actual interpretation skill level of oral surgery residents when it comes to reading CT Facial Bones scans for trauma patients.
Mascarenhas W, Richmond D, Chiasson G. CTRead-A Revolutionary Approach to Training Residents in Computed Tomography Facial Bone Interpretation.
J Oral Maxillofac Surg. 2019 Apr 23. pii: S0278-2391(19)30447-1. doi: 10.1016/j.joms.2019.04.016. [Epub ahead of print]
AO CMFS-18-14P Project title: Antibacterial nano-biomaterials for the purposes of cranio- maxillofacial surgeryInfections associated with implantable devices, also known as biomaterial associated infections (BAIs) pose a real problem in contemporary regenerative medicine and traumatology. In the head and neck area extraoral BAIs manifest as “pin sites infections” (PSI), while intraoral are known as peri-implant mucositis and/or peri-implantitis, which affects the underlying alveolar bone. Despite efforts in bioengineering to improve the biocompatibility of the metallic biomaterials, which constitute a major part of the reconstructive surgery, the problem of bacterial settlement and infection development still poses a serious threat for the treatment outcome. Along with nanotechnology evolution, antibacterial approaches with the use of different nanoparticles (NPs) were taken into concern. However, studies showed that such devices exhibited some limitations, mostly due to a restricted effective release rate, an initial burst release, cytotoxicity and unknown interactions of NPs with the host’s biomolecules. The aim of this study is twofold. First is to evaluate antibacterial activity of nano-sized zinc compounds against the bacteria responsible for infections around the biomaterials in the head and neck area. Second is to evaluate the stability of the nano-colloidal suspensions in the human and artificial saliva, and physico-chemical properties of the nano-particle-protein-sugar complexes, known as protein-coronas (PCs), in such environments which determine the activity of the NPs in the living organisms.
2019 - Pokrowiecki R, Wojnarowicz J, Zareba T, Koltsov I, Lojkowski W, Tyski S, Mielczarek A, Zawadzki P. Nanoparticles and human saliva: a step towards drug delivery systems for dental and craniofacial biomaterials. International Journal of Nanomedicine (Future Medicine). 2019:14, 9235-9257 Manuscript number NNM-2019-0189 (original article). doi: 10.2147/IJN.S221608
Pokrowiecki R. The paradigm shift for drug delivery systems for oral and maxillofacial implants. Drug Deliv. 2018 Nov;25(1):1504-1515. doi: 10.1080/10717544.2018.1477855.
Palka K, Pokrowiecki R, Krzywicka M. Chapter 13: Porous titanium materials and applications in “Titanium for Consumer Applications” Book. 1st Ed. ISBN: 9780128158203. Elsevier, 2019.
AO CMFS-18-25R Project title: Investigating effects of BMPER on osteogenic and chondrogenic differentiationBone morphogenetic proteins (BMPs) 2 and 7 have been approved for clinical use, yet complications limit their application. In addition, the supraphysiological doses applied would indicate that their use has not yet been optimized. BMP binding endothelial regulator (BMPER) also known as Crossveinless 2 was first identified as critical mediator in vein development (Conley, Silburn et al. 2000). Today it is known that BMPER is a BMP modulator, similar to Chordin, Noggin or Gremlin and interacts with BMP 2, 4, 6, 7, 9 and 10. In humans, the syndrome Diaphanospondylodysostosis (DSD) is caused by a lack / mutation of the BMPER protein. Characteristics are absent or severely delayed ossiﬁcation of vertebral bodies and other bone defects, a short broad thorax, a short neck and respiratory insufﬁciency. The severe bone phenotype suggests that BMPER plays a major role in osteogenesis, yet it has been largely overlooked. No studies have been performed to assess whether BMPER as BMP modulator might be as osteoinductive as BMPs themselves nor whether BMPER is able to potentiate the osteoinductive effects of BMPs. The aim of our study is therefore to identify the osteogenic and chondogenic potential effects of BMPER and to establish whether BMPER is promising as a new factor for promoting bone and/ or cartilage regeneration. As a first step the effects of BMPER on MSCs (Mesenchymal stem cells) will be investigated in vitro.
AOCMFS-19-07N Project title: Trilineage differentiation potential of periosteal cells from endochondral and intramembranous originThe periosteum is a highly vascularized bilayer membrane covering the surfaces of bone. The outer “fibrous” layer consists of fibroblasts abundant amounts of extracellular components such as collagens and elastin giving stability and elasticity to the periosteum. In contrast, the inner “cambium” layer contains progenitor cells which are crucial for bone formation and repair. The periosteum exhibits osteogenic potential and has received considerable attention as a promising cell source for bone regeneration strategies. The high proliferation capacity and the simple availability compared to other sources of mesenchymal progenitor cells display big advantages as in vitro cell expansion is often a prerequisite for tissue engineered constructs. However, if and to which extent the harvest location affects the function of the periosteal derived cells is still unclear.
In the framework of this project we aim to compare the in vitro differentiation potential of human periosteum derived cells (hPDC) from endochondral and intramembranous origin. We hypothesize that differences in the developmental origin of the periosteum will influence the behavior and/or potency of hPDCs. We assume that due to the natural tendency for intramembranous ossification and the uniquely high bone remodeling occurring within the jaw, human JPDCs (jaw periosteal derived cells) represent a progenitor cell source with superior osteogenic properties. This would make hJPDCs more favorable for tissue engineering and regenerative medicine (TERM) of intramembranous bone.
This study is crucial for the characterization of hPDCs and can be used to guide clinical strategies that exploit periostea for tissue engineering and clinical applications. The present project may foster translational approaches for bone constructs which is of major interest for cranio-maxillofacial-, trauma- and orthopedic surgery.
AOCMFS-19-15K Project title: Osteoinductive potential of local administration of recombinant BMP9 in the bone defects in mice systemically treated with a monoclonal RANKL antibody drugThe monoclonal antibodies against Receptor Activator for Nuclear Factor Kappa-B Ligand (RANKL) such as denosumab, are used for the antibody mediated anti-resorptive therapies (AMARTs) in patients with metastatic cancer of the bone or osteoporosis. Bone augmentation procedures in the patients having AMARTs should be carefully considered due to the risk of antiresorptive agent-related osteonecrosis of the jaw (ARONJ). Therefore, the promising bone regeneration procedure is demanded for the patients with ARONJ risk.
In the past years, BMP9 has been characterized as one of most osteogenic bone-inducers among the BMP family. Our previous in vitro and in vivo reports revealed that recombinant human (rh)BMP9 demonstrated higher osteoinductive potential when compared to rhBMP2. Furthermore, our previous preliminary data interestingly showed positive effect of rhBMP2 on bone formation in mice after anti-murine monoclonal RANKL antibody (mAb) treatment. It is hypothesized that the local administration of rhBMP9 could further promote bone regeneration in animals having AMARTS. In this project, the recently commercially available mAb is used to create an AMART model in mice. Thereafter, rhBMP9 combined with collagen scaffold will be implanted in calvarial defects. After 4 weeks, the systemic effect of mAb and/or rhBMP9 treatment will be tested by measuring serum ALP level, TRAP-5b level and bone mineral density (BMD). The bone formation in the defects will be evaluated by microCT analysis, histomorphometry and immunohistochemical approach.
This project will show for the first time the effect of the rhBMP9 on bone regeneration potential in an AMART animal model. The results will contribute future bone regenerative therapy for the patients having AMARTS.
AOCMFS-20-05M Project title: MRRead – A Novel Approach to Training Residents in MRI TMJ InterpretationTemporomandibular disorders (TMD) are a common occurrence worldwide which can lead to a plethora of functional and emotional sequelae. Proper diagnosis of the direction, extent, and displacement of TMJ disorders by oral surgeons using the gold standard MRI TMJ Open and Closed views is imperative to improve patient outcomes and avoid unnecessary complications. Despite the importance of accurate diagnosis, oral surgery residents often receive a variable level of MRI interpretation training from a senior resident or staff in an unstructured manner. To address this inconsistency in training, this project aims to create a standardized, scalable training module called MRRead for all residents in oral and maxillofacial surgery so that they can become competent and confident when interpreting MRIs of the TMJ and presenting them to their fellow residents and staff. MRRead will be a web-based training module which will take a student, resident, or even staff member through the reading of a MRI scan one step at a time. Users will be shown normal MRI scans, taught how to interpret anatomy, and then taught how to identify common disorders in temporomandibular joints such as anterior disc displacement, joint effusion, osteoarthritis, etc. To test the effectiveness of MRRead, participants’ confidence level and actual interpretation skill will be assessed via a mandatory short but comprehensive survey and marked MRI interpretation quiz at the beginning and end of the training module. This will allow us to gather key information users’ confidence in interpreting MRI scans, and their ability to accurately diagnose traumatic fractures as they progress through the module. It is hoped that completion of MRRead will lead to a significant increase in both confidence level and actual interpretation skill level of oral surgery residents when it comes to reading MRI TMJs for patients.
AOCMFS-20-16T Project title: Development of Virtual Reality based training in orthognathic surgery for CMF surgeonsThorough understanding of the spatial relationship of 3D anatomical structures is of paramount importance for physicians in general, and for surgeons operating on patients in particular. In craniomaxillofacial (CMF) surgery, the anatomy is complex and many important structures run in close proximity.
Nowadays, knowledge and understanding of these complex 3D shapes have to be learnt largely from images in books and screens, which lack the real 3D nature, and also do not permit interaction. It is well known that 3D interaction and immersion can contribute to a better understanding of objects around us. This accounts for all areas of the CMF surgery, but in particular for orthognathic surgery. The purpose of this project therefore, is to develop a Virtual Reality (VR)-based application that permits CMF residents to visualize and interact with facial skeleton in an immersive environment performing the LeFort I osteotomy and the bilateral sagittal split osteotomy (BSSO). More specifically, we will develop an application that allows them to: 1) provide insight in anatomical structures in the maxillary and mandibular region in a VR environment; 2) interact with these models by performing a leFort I osteotomy and a BSSO. While cutting through the bones the surgeons receive feedback from their handling via scoring. In this feedback, accuracy of the osteotomy and overall progress of handling can be reported.
There is a rapidly growing interest in the use of intelligent tools in virtual simulation of various applications for different training purposes. However, to the best of our knowledge there are none in the CMF-field. Aiming to simulate orthognathic surgery and effectively train clinicians to perform surgeries properly, we will develop in the VR-simulator for orthognathic surgery also a new tool to test the efficacy of the VR-simulator. The tool in the VR-simulator can provide the participants with real-time feedback to assist with training. The presented study aims to investigate evidence of validity of the tool while acquiring meaningful feedback regarding the potential use of the simulator and to get feedback from participants how they evaluate the use of VR in their training of orthognathic surgery.
AOCMFS-20-21D Project Title: The Orbital Index: A Quantitative Tool for Prediction of Delayed Enophthalmos in Orbital Floor Fracture ManagementEarly identification of surgical indication is critical to optimizing outcomes in orbital floor fracture management. Delay of repair in this cohort risks persistent diplopia, persistent facial deformity, and infraorbital nerve injury. While muscle entrapment and acute globe malposition are widely accepted as absolute indications for repair, it has remained a challenge to identify those patients at risk for developing delayed enophthalmos and requiring subsequent surgery. The objective of this project is thus to validate a novel comprehensive quantitative clinically applicable prediction tool that guides orbital floor fracture management by stratifying risk for enophthalmos and establishing a threshold value for surgical intervention.
AOCMFS-21-15L Project title: Releasing the "brakes" to drive tissue repair: targeting non-coding RNAs for bone regeneration
The treatment of large bone defects remains a major challenge for craniomaxillofacial (CMF) surgeons. Critical-sized bone defects are generally reconstructed with autologous bone grafts, but the procedure suffers from several disadvantages including limited tissue availability, donor-site morbidity and prolonged patient hospitalisation. This project aims to develop an effective strategy using mesenchymal stem cells (MSCs) enhanced by RNA therapy for the regeneration of large bone defects.
Cell therapy strategies using MSCs hold a great deal of promise for bone regeneration, but they have yet to become common clinical practice. A key factor contributing to this lack of progression is the inadequate vascularisation of MSC-based grafts, which can lead to necrosis of the constructs. There is increasing evidence that this challenge may be overcome by implanting chondrogenically-primed MSCs to induce endochondral ossification, the natural pathway of bone formation via a cartilage template. During this process, the MSC-derived cartilage induces the infiltration of blood vessels and remodelling into mature bone. Unfortunately, the chondrogenic priming of the cells requires extensive in vitro handling which severely hinders possible translation to the patient. In this project we will devise a new approach that will remove the need for prolonged in vitro pre-differentiation steps to induce MSC-mediated endochondral ossification in vivo. MSC commitment to the endochondral pathway will be achieved by blocking the activity of inhibitory non-coding RNAs (ncRNAs), regulatory molecules that can repress MSC differentiation. In the first phase of the project we will perform RNA-sequencing studies to unravel the changes in ncRNAs that occur in MSCs during the chondrogenic priming phase of endochondral ossification. This will lead us to identify key inhibitors of the process that can be targeted as molecular switches to trigger chondrogenesis and bone formation. Finally, we will establish a scaffold-based system to induce MSC-mediated endochondral ossification via delivery of anti-ncRNAs in situ, replacing the step of in vitro pre-differentiation. Ultimately, our study will provide proof-of-concept that blocking inhibitory ncRNAs in MSCs upon implantation removes the need for chondrogenic priming and leads to endochondral bone formation. This will bring tissue engineering strategies using MSCs and endochondral ossification closer to clinical application.
AOCMFS-21-23A Project title: microRNAs: new tools for craniomaxillofacial bone repair (miR4CMF)
microRNA (miRNA) therapeutics have emerged as a promising strategy for a broad range of diseases, yet their use for craniomaxillofacial applications remains largely unexplored. Modulation of miRNA levels in Mesenchymal Stem/Stromal Cells (MSC) is a novel approach to enhance their pro-regenerative properties and accelerate bone repair. We and others have shown that modulation of miRNAs can induce osteogenic differentiation and neovascularization, two crucial mechanisms for bone repair and regeneration. Also, we showed that cell construct priming in vitro promotes better in vivo outcomes.
miR4CMF aims to explore miRNA-engineered MSCs to modulate extracellular matrix (ECM) properties into a pro-regenerative, pro-osteogenic and pro-angiogenic profile, as an innovative solution to repair craniomaxillofacial fractures and defects. Specifically, it will: i) develop a 3D in vitro culture of miRNA-engineered MSC and ii) characterize the MSC newly synthetized pro-regenerative ECM, which in combination with the miRNA-induced MSC will work as seeding centers for new bone formation; iii) perform an in vivo proof-of-concept for the synergistic impact of miRNA-engineered MSC and their ECM in new bone formation, using the calvarial bone defect model.
miR4CMF will respond to the following scientific questions:
1. Are miRNAs useful tools to promote the synthesis and deposition of a pro-osteogenic and a pro-angiogenic bone ECM?
2. Can miRNA-engineered MSC and their synthetized ECM act synergistically to repair craniomaxillofacial fractures and defects?
Using miRNA-based molecular engineering to promote an intracellular pro-osteogenic MSC profile, together with the synthesis of a pro-regenerative ECM, this project will offer a novel strategy to accelerate bone craniomaxillofacial regeneration. Importantly, this proposal opens a new line of investigation in the repair/regeneration of craniomaxillofacial fractures and defects.
AOCMFS-21-31V Project title: Towards the application of augmented navigation with HoloLens in orthognathic surgery
Computer-aided technologies have revolutionized orthognathic surgery (OS) facilitating cephalometric analysis, surgical simulation, and the fabrication of splints and patient-specific implants. Despite the increasing body of evidence that these techniques are improving accuracy of surgical outcome, wide implementation is limited due to relatively high costs and the time-consuming and complex handling of the software. Alternatively, the application of navigation systems for OS could potentially speed up part of the process through bypassing the necessity of intraoperative surgical guides and splints. So far, navigation has been successfully used for various CMF surgical interventions such as mandibular reconstruction, bony contouring, and maxillary repositioning (2). However, the use of conventional navigation systems for surgery faces three challenges: the depth perception, the hand-eye coordination, and the continuous switch of focus between the navigation screen and the operation site.
Augmented reality (AR) helps in addressing these challenges. This technology brings 3D patient-specific data into the view of the surgeon. By using an AR device, drilling paths, and cutting planes are visualized at the right location, thus eliminating the need to look away from the surgical site. Additionally, AR headsets provide a stereoscopic view of the 3D model which makes it easy to understand the 3D shape of the targeted anatomy. We developed a new augmented reality navigation system with an integrated HoloLens 2 for surgical purposes, that allows an integration of an AR device with a conventional navigation system . The method does not require any adaption of the AR device, and uses a multi-modal marker for aligning the AR device with the navigation system’s coordinate system. The use of this system requires a thorough pre-clinical evaluation. Therefore, four surgeons will use the AR navigation system in a series of phantom trials. The phantoms consist of 3D printed mid-face regions of 20 patients where the drilling trajectories and the cutting planes on each phantom is planned preoperatively. Subsequently, the planning data is imported into the AR system using the HoloLens 2 which projects the 3D virtual models on top of the phantom models. The operators will perform the procedure assisted by the AR visualization, and the comparison between postoperative outcome and preoperative planning will determine the system’s performance.
AOCMFS-22-05C Project title: Augmented reality in Head and Neck surgery. Use of the Hololens2 in planning and performing a fibular free flap reconstruction for a facial hard-tissue defect
Augmented Reality (AR) is the projection of a computer created image onto the observer’s real environment. AR can allow the projection of medical images such as CT scans onto a patient during surgery. This additional information can help guide surgeons during the procedure, showing the surgeon where to place bone cuts, screws and prostheses. This will allow the surgeon to see patient’s anatomy beyond the surgical incision. Therefore surgery can be performed through a smaller cut. Currently, we use cutting guides on bones which act like stencils. In contrast to AR guides, cutting guides are physical objects. They take weeks to produce and are not re-usable.
To compare the accuracy of AR guided bone cuts and cutting-guide guided bone cuts against pre-operative planning.
30 surgeons in total will be recruited and asked to produce a total of 18 cuts on 3D printed fibula models using a surgical saw and fissure burs. 6 cuts will be made using AR guidance, 6 using cutting guides (control group) and 6 using AR guidance to locate the cutting guide onto the model. The produced bone cuts will undergo CT scan and analysed digitally.
Dice-coefficient and Hausdorff analysis will be used to compare the cut bone models and the pre-operative planned models. This will allow comparison of the 3 experiment arms.
If AR is shown to be within acceptable accuracy to guide bone cuts, this experimental model can be used in cadaver studies. AR guided surgery has the benefit of having a short turn-around, it can be modified intra-operatively by the surgeon. It is a much cheaper system and better environmental sustainability profile. This is because the AR Head Mounted Device is reusable.
The same technique can be subsequently applied to other areas of CMF surgery. In CMF trauma, the facial bones are often broken into many small pieces. AR projection of CT scan will allow all the bone fragments to be seen virtually without being fully exposed surgically. It will allow on-table visualisation of hard tissue, minimising surgical access and morbidity.
AOCMFS-22-09G Project title: Fractional laser combined with self-regenerating cartilage to repair the temporomandibular jointAfter chronic low back pain, temporomandibular disorders (TMD’s) are the second most common musculoskeletal condition affecting 5-12% of the population, with an annual health cost burden estimated at $4 billion worldwide. Temporomandibular joint osteoarthritis (TMJOA) is a subtype of TMD characterized by slow and progressive degeneration of the mandibular condyle cartilage and bone, dramatically impacting function and quality of life. The aim of this study is to use a novel approach that evaluates the use of fractional laser treatment in cartilage combined with our method for generating new cartilage matrix using dynamic Self-Regenerating Cartilage (dSRC) to regenerate articulating cartilage defects in a rabbit TMJ model. To form the dSRC, freshly harvested rabbit ear chondrocytes will be placed into sealed 15-mL polypropylene tubes and cultured on a rocker at 40 cycles per minute for 14 days at 37°C. Chondrocytes aggregate and generate new extracellular matrix forming a pellet of dSRC. Microchannels of approximately 300-500 µm diameter will be created by infrared laser ablation in freshly harvested rabbit TMJ condyles. To evaluate cartilage generation ex vivo, the dSRC aggregates will be implanted in laser-ablated microchannels in rabbit TMJ condyle articular cartilage. dSRC samples after 2 weeks of in vitro culture and samples of native articular cartilage will be stained with H&E to evaluate chondrocyte density and neocartilage integration. Safranin O (sulfated GAG) staining, and Toluidine blue (proteoglycan) staining will also be performed to assess the biochemical composition of the neomatrix. To evaluate this combined approach in vivo, 16 New Zealand white rabbits will be used. Both TMJ condyles will be surgically accessed using a minimally invasive approach developed by our group. Laser-ablated microchannels will be created in the TMJ condyle cartilage and two groups will be studied: Group I – laser-ablated microchannels (empty; n=16 condyles) and Group II – laser-ablated microchannels+dSCR (n=16 condyles). Rabbits will be euthanized at 4 (n=8) and 8 (n=8) weeks, and the TMJ condyles will be harvested for processing. Condyle articular cartilage regeneration will be performed using micro-CT analysis, histological analysis (H&E, Masson’s Trichrome, Safranin O, and Toluidine Blue staining to assess the biochemical composition of the neomatrix) and immunohistochemical analysis of collagens type I (fibrocartilage) and type II (hyaline cartilage).
AOCMFS-22-17P Project title: Perioperative management and monitoring of microvascular flaps using mobile hyperspectral imaging
Free flap tissue transfer has success rates ranging from 91 to 95%. Complications are often due to vascular compromise and require surgical intervention. The gold standard of flap monitoring is clinical assessment (flap color, capillary refill, tissue turgor and temperature) and handheld Doppler sonograph. At out department additional measures such as the implantation of a Doppler probe (Cook-Swartz-Flow-Probe, CSFP) at either the venous or arterial vessel are also standard. Other techniques include color duplex ultrasonography, fluorescence angiography or laser Doppler flowmetry and microdialysis are also available. So far none of the methods have been able to show its superiority because of the lack of data.
Hyperspectral imaging (HSI) is a new in vivo imaging technique that combines the principles of spectroscopy and imaging in a non-contact fashion to provide information about tissue morphology, composition, and physiology. HIS creates high resolution images that contribute information about oxygenation or ischemia in superficial tissue levels.
We aim to conduct a study to compare the use of a mobile and portable HIS-camera with clinical monitoring and CSFP. A total of 50 free tissue flaps (25 with skin-island and 25 without skin island) will be included in the study. Postoperative flap assessment will be performed by standard clinical monitoring (flap color, capillary refill, tissue turgor, temperature) and checking of the CSFP every 2 hours for the first 24 hours and every 4 hours until 72 hours postoperatively. In addition to this the use of the mobile and portable HIS-camera will be implemented. At every 2 hours the commercially available TIVITA mobile (Diaspective Vision GmbH, Germany) HSI-camera and its evaluation software is used for flap monitoring. Tissue oxygenation (StO2), Tissue-Hemoglobin-Index (THI) Tissue-Water Index (TWI), Tissue-Lipide Index (TLI) and Near infrared perfusion index (NIR PI) are evaluated during the first 72 hours postoperatively. Aim of the study is to find a cut-off in these values where flap revision surgery must be performed. First there is the need to correlate the findings of clinical assessment, CSFP and HSI. In cases where revision surgery had to be performed the course of clinical monitoring, CSFP and HSI will further be investigated.
AOCMFS-22-18K Project title: Preliminary clinical study on the treatment of segmental mandibular defects using a Ti-cage implant
The current standard procedure to restore mandibular continuity defects involves free tissue transfer with an autologous composite bone flap. Even though success rates are high, several critical drawbacks have been associated with this procedure, including severe donor site morbidity, long hospital stay and recovery process, need for high surgical expertise, insufficient bone graft height, and mechanical failure of the plating system. A systematic approach for the designing and testing of patient-specific implants used as an alternative to the free flap procedure appears to be still lacking.
The goal of this project is to conduct a preliminary clinical study on the reconstruction of a lateral segmental defect following mandibulectomy using a 3D printed patient-specific titanium cage implant. Qualified patients will require reconstruction following segmental resection for a benign defect in the lateral mandible and have no indication for radiotherapy. In these cases, a normal viable and adequately vascularized soft tissue bed is expected. The reconstruction cage will be designed through a semi¬-automatic workflow for designing patient¬ specific mandibular reconstruction implants in the Materialise Mimics® and Materialise 3-Matic® software environment. Comparison of specific implant design variables (e.g. number of screws, screw position, and screw type) will be made prior to clinical application using topology optimization techniques. The biomechanical performance of the different implant designs will be evaluated through validated computational finite element analyses and experimental testing. The porous and cage-shaped design of the implant provides the possibility for the insertion of autografts harvested with minimal donor side morbidity, as well as the subsequent integration of dental implants. Post-operative monitoring using (CB)CT scan imaging following surgery will take place to quantify bone ingrowth and graft healing. Aesthetical and functional outcomes of the reconstructive procedure will be assessed using a patient-perceived quality of life questionnaire. A successful in-house study on the semi-automated implant designing, computational modeling and biomechanical testing of a patient-specific proof-of-concept implant highlights the potential of the proposed framework to yield more cost- and time-effective pre-surgical planning and result in implant designs that can minimize morbidity and maximize aesthetic and functional outcomes.
AOCMFS-22-23K Project title: MOBILIZING MECHANOBIOLOGY OF PERIOSTEAL CELLS FOR CRANIO-FACIAL BONE REGENERATION
Bone periosteum is a natural scaffold and a source of regenerative cells and bioactive factors that promote osteogenesis. The areas in which the periosteal cells are subjected to mechanical loading co-localize with the greatest new bone deposition. The regenerative pathways during periosteal distraction osteogenesis (PDO) depend on the duration and magnitude of tensile stress. Our preliminary data indicate that the distraction alternated with relaxation, named “pumping of periosteum” (PP) results in enhanced osteogenic capacity of periosteum. While the histological features associated with PDO have been described, the underlying molecular mechanisms remain unknown. Our objective is to clarify the interaction between the periosteum and the underlying tissues in response to mechanical stimuli, by using a rat model of calvarial regeneration. In parallel, the same studies will be conducted using a mechanical loading bioreactor, a model that allows extension to controlled studies of human bone regeneration. To this end, we intend to: 1. Examine bone formation following PP protocol at different time points (Aim 1), and 2. Analyse the expression of bone-specific genes on the mRNA and protein levels (Aim 2). Following a latency period, the PP protocol alternating relaxation with activation will be systematically compared to the conventional PDO protocol. The amounts of (i) new tissue generated relative to the area confined by the parental bone, (ii) periosteum and (iii) distraction plate, will be determined histomorphometrically and by micro-CT. In both models, molecular differences between the two modes of periosteal elevation will be related to the alterations in the expression of tissue-specific proteins. We expect that the parameters of periosteal manipulation will induce expression of osteogenic differentiation markers and influence the nature and kinetics of bone formation in places that would otherwise never become bone. The osteogenesis and the subsequent early stage bone development shall involve a mechanism, which detects and responds to the level and duration of hydrodynamic shear forces. Consequently, we propose to elucidate the mechanobiological principles governing hard tissue formation during different modes of periosteal elevation. The outcomes of this work would impact our understanding of the role of periosteum in bone augmentation and ultimately, enable a paradigm shift in the field of regenerative medicine.