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Background Recently, medical rapid prototyping (MRP) models, fabricated with computer-aided design and computer-aided manufacture (CAD/CAM) techniques, have been applied to reconstructive surgery in the treatment of head and neck cancers. Here, we tested the use of preoperatively manufactured reconstruction plates, which were produced using MRP models. The clinical efficacy and esthetic outcome of using these products in mandibular reconstruction was evaluated. Methods A series of 28 patients with malignant oral tumors underwent unilateral segmental resection of the mandible and simultaneous mandibular reconstruction. Twelve patients were treated with prebent reconstruction plates that were molded to MRP mandibular models designed with CAD/CAM techniques and fabricated on a combined powder bed and inkjet head three-dimensional printer. The remaining 16 patients were treated using conventional reconstruction methods. The surgical and esthetic outcomes of the two groups were compared by imaging analysis using post-operative panoramic tomography. Results The mandibular symmetry in patients receiving the MRP-model-based prebent plates was significantly better than that in patients receiving conventional reconstructive surgery. Conclusions Patients with head and neck cancer undergoing reconstructive surgery using a prebent reconstruction plate fabricated according to an MRP mandibular model showed improved mandibular contour compared to patients undergoing conventional mandibular reconstruction. Thus, use of this new technology for mandibular reconstruction results in an improved esthetic outcome with the potential for improved quality of life for patients.

Background Advanced head and neck malignancies with underlying bony involvement often require aggressive oncological resection of large segments of the oral cavity including the mandible. These patients require vascularized donor osseous free tissue transfer to reconstruct significant defects. Traditionally, the donor bone is harvested on its vascular supply and shaped to the defect in a free hand fashion (FHS). However, virtual surgical planning (VSP) has emerged as a method to optimize reconstructive outcomes and decrease operative time. The goals of this study are to assess superiority of VSP to FHS by comparing bony union rates at 12 months, short and long-term complication rates, reconstruction accuracy, quality of life (QOL), functional outcomes, and economic analysis. Methods This is a multicenter phase II/III study randomizing four hundred twenty head and neck patients undergoing mandibulectomy in a 1:1 ratio between VSP and FHS. Intention-to-treat analysis will be performed for patients enrolled but unable to undergo VSP-aided reconstruction. The primary endpoint is bony-union rates at 1 year post-operatively. Secondary outcomes include complication rates, QOL, functional outcomes, and economic burden. Discussion This study will provide an assessment of two different surgical approaches to the reconstructive methods of mandible defects using fibular or scapular free flaps on bony-union rates, complications, QOL and economics. Trial registration Clinicaltrials.gov identifier: NCT05429099. Date of registration: June 23, 2022. Current version: 1.0 on March 6, 2024.

To investigate bone remodelling responses to mandibulectomy, a joint external and internal remodelling algorithm is developed here by incorporating patient-specific longitudinal data. The primary aim of this study is to simulate bone remodelling activity in the conjunction region with a fibula free flap (FFF) reconstruction by correlating with a 28-month clinical follow-up. The secondary goal of this study is to compare the long-term outcomes of different designs of fixation plate with specific screw positioning. The results indicated that the overall bone density decreased over time, except for the Docking Site (namely DS1, a region of interest in mandibular symphysis with the conjunction of the bone union), in which the decrease of bone density ceased later and was followed by bone apposition. A negligible influence on bone remodeling outcome was found for different screw positioning. This study is believed to be the first of its kind for computationally simulating the bone turn-over process after FFF maxillofacial reconstruction by correlating with patient-specific follow-up.

In cases of large mandibular continuity defects resulting from malignancy resection, the current standard of care involves using patient-specific/custom titanium reconstruction plates along with autogenous grafts (fibula, scapula, or iliac crest segments). However, when grafts are not feasible or desired, only the reconstruction plate is used to bridge the gap. Unfortunately, metal osteosynthesis and reconstruction plates, including titanium, exhibit adverse effects such as stress-shielding and limitations in accurate postoperative irradiation (especially with proton-beam therapy). To address these issues, in this study we explore, develop and validate a non-metallic solution: a topology-optimized polyetheretherketone (PEEK) load-bearing implant for large non-grafted mandibular continuity defects. In order to thoroughly validate the developed PEEK reconstruction, a dedicated MANDYBILATOR testing apparatus was developed. Using the MANDYBILATOR finite element analysis results of the implant were confirmed and the PEEK implant was mechanically validated for both static and dynamic loading. Results show that the PEEK reconstructed mandible is comparably strong as the unreconstructed mandible and is unlikely to fail due to fatigue. Our PEEK implant design has the mechanical potential to act as a substitute for the current titanium plates used in the reconstruction of continuity defects of the mandible. This may potentially lead to optimised patient-specific reconstructions, with the implants matching the bone’s stiffness and possessing radiolucent properties which are useful for radiographic follow-ups and radiotherapy. Furthermore, the addition of the dynamic/cyclic MANDYBILATOR apparatus allows for more realistic application of the in-vivo loading of the mandible and can provide added insights in biomechanical behaviour of the mandible.

Background Mandibular tumors significantly impact patient health and quality of life. Surgical resection is the primary treatment, often necessitating reconstruction to restore appearance and function. Traditional surgical methods rely heavily on surgeon experience, posing risks such as excessive blood loss and facial paralysis. The advent of digital and robotic-assisted surgical technologies offers improved precision and outcomes. Methods The study included five pairs of models with mandibular tumors, divided into a control group (traditional surgery) and an experimental group (robot-assisted surgery). In the experimental group, procedures were performed using a robot-assisted electromagnetic surgical navigation system, following alignment with the preoperative design under robotic guidance. Conversely, the control group underwent traditional surgery, where osteotomy positions were estimated empirically based on the preoperative design. Postoperative CT scans were used to compare the actual outcomes with the preoperative plans. The osteotomy accuracy and reconstruction outcome were evaluated by measuring the positional and angular errors between the preoperatively designed and actual postoperative data. Results The robot-assisted group demonstrated significantly lower osteotomy distance and angle errors compared to the control group. The reconstruction outcomes in the experimental group also showed superior alignment with preoperative plans, indicating better aesthetic and functional results. Conclusion Robotic-assisted surgery for mandibular tumor resection and reconstruction enhances surgical precision and improves reconstructive outcomes compared to traditional methods. Further research with larger sample sizes and clinical settings is necessary to confirm these findings and expand clinical applications.

Osseous non-union following free flap reconstruction of segmental mandibular defects can prolong patients’ dental rehabilitation. Various plating systems have been developed to optimize biomechanical fixation, but healing may be retarded. Quantifying intersegmental micromovements could help monitor healing but remains challenging. This study investigates a novel method to visualize segmental movements during healing using a fluoroscopy-based approach. To track segment movements, tantalum beads were implanted intraoperatively in the osseous flap and native mandibular segments. Additionally, single-plane fluoroscopic imaging was performed to assess bead position at maximum mouth opening and intercuspation. Bead positions were merged as three-dimensional objects. Intersegmental movements were quantified using model-based roentgen stereophotogrammetry (mbRSA). Exemplarily, preliminary images were collected from one patient. Fluoroscopic imaging with mbRSA effectively displayed movements and allowed quantification. Translation and rotation were assessed between the native mandible and the flap during maximum mouth opening and intercuspation. For the first time, our analyses demonstrate the feasibility of quantifying segment mobility during healing. This first in men study illustrates the feasibility of the method to monitor intersegmental movements in cases of maxillofacial reconstructions. Further research involving larger patient cohorts is necessary to identify relevant thresholds and differentiate from those that result in lack of healing.

Abstract Objective The study aims to compare differences among iliac bone flaps with different iliac crest orientations for the repair of mandibular defects with an aim to analyze their advantages, disadvantages, and effects.Material and methodsClinical data and computed tomography scans of all patients who underwent iliac bone flap repair of the mandible in Peking University School and Hospital of Stomatology from January 2016 to April 2021 were collected. Patients were divided into the iliac crest towards alveolar process (Group A) and the iliac crest towards mandibular inferior margin (Group B). Software was used to measure corresponding indicators. The results obtained for the groups were statistically analyzed.ResultsThe study included 78 patients (25 and 53 in groups A and B, respectively). The symmetry of the LC-type defect was better in group A (p < 0.05). The all-bone width of the alveolar process side in group A was greater than 6 mm; in 15 cases of group B, the width was less than 6 mm (p < 0.05). The intermaxillary distance of two sites were higher in group B (p < 0.05). The bone cortical thickness was significantly thicker in group A (p < 0.05).ConclusionOne year after the mandibular body defect was reconstructed with a vascularized iliac bone flap, the iliac crest towards alveolar process group showed better bone symmetry, width, intermaxillary distance, and cortical thickness to meet the planting requirements.Clinical relevanceThe use of an iliac crest towards alveolar process may be a better approach for mandible reconstruction.

It has been demonstrated that development of three-dimensional printing technology has supported the researchers and surgeons to apply the bone tissue engineering to the oromandibular reconstruction. In this study, poly caprolactone/beta tricalcium phosphate (PCL/β-TCP) scaffolds were fabricated by multi-head deposition system. The feasibility of the three-dimensionally (3D) -printed PCL/β-TCP scaffolds for mandibular reconstruction was examined on critical-sized defect of canine mandible. The scaffold contained the heterogeneous pore sizes for more effective bone ingrowth and additional wing structures for more stable fixation. They were implanted into the mandibular critical-sized defect of which periosteum was bicortically resected. With eight 1-year-old male beagle dogs, experimental groups were divided into 4 groups (n = 4 defects per group, respectively). (a) no further treatment (control), (b) PCL/β-TCP scaffold alone (PCL/TCP), (c) PCL/β-TCP scaffold with recombinant human bone morphogenetic protein-2 (rhBMP-2) (PCL/TCP/BMP2) and (d) PCL/β-TCP scaffold with autogenous bone particles (PCL/TCP/ABP). In micro-computed tomography, PCL/TCP/BMP2 and PCL/TCP/ ABP groups showed significant higher bone volume in comparison to Control and PCL/TCP groups (P < 0.05). In histomorphometric analysis, a trend towards more bone formation was observed in PCL/TCP/BMP2 and PCL/TCP/ABP groups, but the results lacked statistical significance (P = 0.052). Within the limitations of the present study, 3D-printed PCL/β-TCP scaffolds showed acceptable potential for oromandibular reconstruction.

Introduction The aim of this study is to perform a systematic review to compare the outcomes of the different surgical options for mandibular reconstruction in head and neck cancer. Material and methods 93 articles were selected. Four groups were identified: titanium plate without flaps, titanium plate covered by soft tissue flap, bone tissue flaps and double flaps. We compared patients’ characteristics, site of mandibulectomy, type of reconstruction and complications. Results 4697 patients were reported. The groups were not homogeneous regarding the type of defect and the treatment history. A significant difference in terms of post-operative complications was found between group 1 and group 2 ( p  < 0.00001), and between group 2 and group 3 ( p  < 0.00001). Total complications rate for group 4 was significantly higher when compared to group 3 ( p  < 0.00001), but no significant difference was found with group 2. Conclusion These results suggest that mandibular reconstruction using a microvascular bone flap is the best surgical option in patients without significant comorbidities.