Reconstruction Of Mandible Research Articles

Anatomical and technical considerations for planning anterior iliac crest graft cutting guide for mandibular reconstruction: a case report / Considerações anatômicas e técnicas para o planejamento de guia de corte de enxerto de crista ilíaca anterior para reconstrução mandibular: relato de caso

Delayed mandible reconstruction is a challenged situation in Oral and Maxillofacial surgery, due to great quantity of fibrous tissue and quality of covering soft tissue. The virtual surgical planning not only assists in previewing results, it assists in adjust the size and format of bone grafts by means of cutting surgical guides according to the anatomy of regional donor area too. We reported a clinical case a 20-years-old male patient attended to our service presented with segmented mandibular defect. Aiming to perform the procedure with more predictability, accuracy and less morbidity, we planned to remove the anterior portion of the iliac crest bone using a cutting guide computer aided design/computer aided manufacturing which was in accordance with the curvature and the size mandible bone defect.

An Anatomic Analysis of Fibula Flap Mandible Reconstructions: Implications for Endosseous Implant Placement.

Precise planning and evaluation of the fibula bone are necessary if immediate endosseous implant placement is considered. Limited information is available on the anatomical dimensions or density of fibula used in mandibular reconstructions. This study aimed to describe the morphology and dimensions of the fibula used to reconstruct segmental mandibular defects and contrast the findings with the native mandible. A retrospective analysis was performed of patients who underwent segmental mandibulectomy reconstructed with osteocutaneous fibula flaps and had at least one postoperative computed tomography scan. Fibula cross sectional dimensions and densities were evaluated with three-dimensional software. Radiographic measurements were obtained from the contralateral mandible medial to the first molar for comparison. Four hundred seventy-seven fibula cross sections from 159 segments were evaluated. Cross-sectional oval, quadrilateral, triangular, and pentagonal shapes differed significantly in proportion (p < 0.001). Thirty-eight percent of segments (95 percent CI, 30 to 46 percent) had differences in cross-section height greater than 1 mm (p < 0.001). Between segments within the same patient, the median height difference was 1.58 mm (range, 0.14 to 6 mm). The superior cortex density was significantly higher for the fibula than the native mandible; however, the medullary space density was significantly lower (p < 0.001). The current study comprises the most comprehensive description of fibula morphology in mandibular reconstructions and highlights the significant variability that exists. The findings provide justification for the added time and cost of computer-aided design and computer-aided manufacturing in centers interested in performing immediate dental implant placement, as the technology provides the necessary precision and accuracy.

Risk factors associated with fixation-related complications in microsurgical free flap reconstruction of the mandible.

Hardware complications (loosening of screws, infection, or exposure of the plate) in mandibular reconstruction with vascularized osseous free flaps impose significant morbidity, and frequently require revision surgery. Purpose of this study was to identify possible contributing factors for hardware complications. This is a retrospective cohort study involving case series of patients who underwent microvascular mandible reconstructions between 2000 and 2020. Patient demographics, pathological, clinical, and treatment-related factors were analyzed in univariate and multivariate analyses. Ninety-one patients were enrolled, encompassing 63 reconstructions with fibular free flaps, 26 reconstructions with scapular, and 2 reconstructions with iliac flaps. Rate of hardware complications and plate exposure was 14.3% and 7.7%, respectively, with a median follow-up time for extrusion of 29 months. In univariate analysis, preoperative radiotherapy (odds ratio [OR]=6.57, p= .01), and secondary mandible reconstruction (OR=4.3, p= .04) were significant predictors of hardware complications, and plate exposure was most frequently found in secondary reconstruction (37.5%, OR=11.8, p= .04). Hypertension was the most commonly found comorbidity (24%), and it trended toward significance regarding plate exposure (p= .05). Only secondary mandible reconstruction was associated with osteosynthesis complications (OR=12.53, p= .01) and plate exposure (OR=23.86, p= .005) on multivariate analysis, while preoperative radiation therapy did not retain its relevance on plate exposure. Secondary mandible reconstructions with vascularized osseous free flaps have a higher risk of osteosynthesis complications than primary reconstructions.

Masticatory performance in patients undergoing free fibula flap for mandible reconstruction

BackgroundTo explore the masticatory performance in patients undergoing an osteo(cutaneous) free fibula (OFF) flap for mandible reconstruction by a prospective design.MethodsA total of 56 patients who had undergone OFF flap reconstructions for mandibular reconstruction secondary to malignant (squamous cell carcinoma) or benign (ameloblastoma) tumor resection were prospectively enrolled. They were asked to complete the masticatory performance test by the weigh method and the chew domain of the University of Washington quality of life questionnaire (version 4) preoperatively and at 3, 6, and 12 months postoperatively. The pair nonparametric test was used to analyze the dynamic change of masticatory performance and subjective chew function.ResultsFifty-one patients were included for analysis finally. The mean masticatory performance for patients with malignant tumors were 53.4% ± 10.3%, 36.4% ± 10.3%, 42.6% ± 9.6%, 52.8% ± 10.9%, and 53.1% ± 11.8% preoperatively, at 2 weeks, 3 months, 6 months, and 12 months postoperatively, respectively. Compared with the preoperative level, the masticatory performance had a significant reduction immediately after surgery (p < 0.001), followed by a return to the baseline level within three months. A similar trend was noted for those with benign tumors. The mean score of chew domain for patients with malignant tumors were 100 ± 0, 54.3 ± 32.9, 81.4 ± 24.5, and 92.9 ± 17.8 preoperatively, at 3 months, 6 months, and 12 months postoperatively, respectively. Compared with the preoperative level, the subjective chew function was greatly affected within the first three months (p < 0.001), and it gradually recovered to the baseline level in the following nine months. A similar trend was noted in patients with benign tumors.ConclusionsThe masticatory performance and subjective chew function was significantly affected after OFF flap reconstructions in the short term, but both recovered to the preoperative levels within 9–12 months.

Patient-Specific 3D-Printed Miniplates for Free Flap Fixation at the Mandible: A Feasibility Study.

BackgroundThis study was conducted to evaluate the feasibility, clinical outcomes, and accuracy of patient-specific 3D-printed miniplates for mandible reconstruction with fibula free flaps.MethodsA feasibility study was conducted with 8 patients. Following virtual planning, patient-specific 1.0 mm titanium non-locking miniplates were produced via laser selective melting. 3D-printed cutting and drilling guides were used for segmental mandible resection and flap harvesting. Flap fixation was performed with two 4-hole miniplates and 2.0 mm non-locking screws (screw length 7 mm) for each intersegmental gap. Clinical follow-up was at least 6 months. Preoperative and postoperative CT/cone beam CT data were used for 3D accuracy analysis and evaluation of bone healing. Plate-related complications were monitored clinically.ResultsPatient-specific miniplate fixation of all flaps was successfully conducted (4 mono-segmental, 4 dual-segmental) with high accuracy (3.64 ± 1.18 mm) between the virtual plan and postoperative result. No technical complications were encountered intraoperatively. Osseous union occurred in all intersegmental gaps (1 partial, 18 complete) after 10 ± 2 months. No material fracture, dislocation, or plate exposure was observed.ConclusionsBased on this pilot observational study including a limited number of patients, free flap fixation for mandibular reconstruction with patient-specific 3D-printed miniplates is feasible and associated with high accuracy, bone healing, and remote soft tissue complications.

Risk of Osteoradionecrosis in Reconstructed vs.Native Mandibles in Oral Cavity Cancer Following Intensity-Modulated Radiotherapy

<h3>Purpose/Objective(s)</h3> Osteoradionecrosis (ORN) is a serious complication of radiation therapy characterized by non-healing exposed bone, and occurs in 5-35% of head and neck cancers treated with intensity-modulated radiotherapy (IMRT). High radiation dose, oral cavity subsite, and mandibular surgery are known risk factors for ORN development. However, whether mandibles reconstructed with fibular flaps carry an elevated risk of ORN compared to native mandibles in patients with IMRT-treated oral cavity squamous cell carcinoma (OCSCC) is unknown. <h3>Materials/Methods</h3> An IRB-approved database of head and neck cancer patients treated at a tertiary care center was queried for patients with OCSCC treated with surgery and post-operative IMRT. Patients were included if they underwent free flap surgery, received IMRT ≥45 Gy in ≥20 fractions, and completed treatment at least two years prior to analysis to provide adequate follow-up time. ORN was graded according to Schwartz and Kagan classification: grade 1, superficial involvement of mandible; grade 2, exposed cortical bone and underlying medullary bone necrosis; grade 3, full diffuse involvement. Competing risk regression, with death as a competing event, was used to assess risk factors for the development of ORN. <h3>Results</h3> A total of 151 patients met inclusion criteria with median follow-up time of 32.6 months (range 0.2-190.6). Patient demographics included 60.3% male, 88.7% Caucasian, and median age 62.4 years (range 28.1-93.2). Of the 151 patients, 27.8% were current smokers and 45.7% were former smokers. Oral cavity subsites were grouped as lateralized tumors in 32.5% of patients (11.9% buccal mucosa, 8.6% retromolar trigone, 6.0% alveolar ridge, 4.0% gingiva, and 2.0% hard palate) and midline tumors in 67.6% of patients (21.2% floor of mouth, 46.4% mobile (oral) tongue). Reconstruction with soft-tissue free flap was performed in 74.8% of patients, and 25.2% of patients underwent fibular flap for mandibular reconstruction. Median radiation dose was 60 Gy in 30 fractions. ORN occurred in 13.9% of patients (n=21; 11 grade 1, 3 grade 2, 7 grade 3) and 42.4% of patients died without ORN. For patients who developed ORN, the median time to ORN was 23.9 months (range 2.4-71.2). On univariate analysis, no individual factors were associated with development of ORN; the 1-year (5.4%, 95%CI 2.5-9.8%) and 2-year (7.5%, 95%CI 3.9-12.5%) rates of ORN were low. <h3>Conclusion</h3> Fibular flap mandibular reconstruction was not associated with increased risk of developing mandibular ORN compared to native mandibles in patients with oral cavity cancer following IMRT. The risk of ORN in patients treated with IMRT after mandible reconstruction is low, and fibular flaps can be safely performed with no excess concern for this mandibular ORN. Larger prospective studies are needed to definitively assess risk factors for development of ORN in this patient population.

Reduction of CT Artifacts Using Polyetheretherketone (PEEK), Polyetherketoneketone (PEKK), Polyphenylsulfone (PPSU), and Polyethylene (PE) Reconstruction Plates in Oral Oncology

Surgical reconstruction after segmental mandibulectomy in patients with oral cancer commonly requires implantation of titanium plates, which cause metallic artifacts in CT examinations detrimental for image quality. Therefore, the aim of the present study was to evaluate CT artifacts and image quality of the polymer plate materials polyetheretherketone (PEEK), polyetherketoneketone (PEKK), polyphenylsulfone (PPSU), and polyethylene (PE) in mandible reconstruction. Five plates (titanium, PEEK, PEKK, PPSU, and PE) were successively surgically inserted in a human cadaveric specimen using eight (1) titanium and (2) zirconium oxide screws. Streak and blooming artifacts were assessed in 1mm CT scans with and without metallic artifact reduction algorithms (MAR) in this cross-sectional study. The different plate materials were analyzed for their effect on Hounsfield unit (HU) values resulting in streak artifacts. Blooming artifacts were measured as virtual growth of plates compared to actual size. Subjective image quality was assessed by 3 independent observers. Statistics were conducted by multifactorial ANOVA and Bonferroni's post hoc test. Titanium (182.42 HU; SD±3.09) was associated with significantly more streak and blooming artifacts compared to the polymers PEEK (86.41 HU; SD±1.72; P<.001), PEKK (85.50 HU; SD±2.75; P<.001), PPSU (85.51 HU; SD±1.97; P<.001), and PE (85.52 HU; SD±3.33; P<.001) implants. No significant differences could be seen between the screw types (titanium vs zirconium oxide) (P=.75) or the activation or inactivation of MAR (P=.85). Image quality was best for PE and worst for titanium implants in combination with zirconium oxide screws. Polymers plate materials PEEK, PEKK, PPSU, and PE significantly reduce CT artifacts and improve image quality facilitating the radiological interpretation of implant surrounding tissues. This effect is beneficial for radiological tumor follow-up and CT-based planning of adjuvant radiotherapy.

Analysis of the effects of mandibular reconstruction based on microvascular free flaps after oncological resections in 21 patients, using 3D planning, surgical templates and individual implants

IntroductionPost- resection defects in the area of the head and neck frequently result in functional impairment of the masticatory system and unaesthetic outcome in the facial appearance. In pediatric population they exert a devastating effect on speech development, breathing and facial growth leading to secondary deformations which are extremely challenging in reconstruction by means of conventional surgery protocols. Material and Methods21 patients (14 males/ 7 females) aged 4–17 years old, treated between 2015 and 2019 due to malignant/benign tumors or congenital deformities requiring mandible resection were enrolled in the study. All patients underwent Virtual Surgical Planning (VSP), mandible tumor resection with use surgery guides and defect reconstruction with microvascular bone graft supported with custom implants. Postoperatively, 3D models used for the planning and postoperative 3D model of the reconstructed mandible were compared using authors method based on easily measurable morphometric measurements (3 angles, 3 linear dimensions), allowing a three-dimensional quantitative assessment of postoperative outcomes of the surgery. Linear regression analysis and one-way analysis of variance were used to evaluate the clinical material. The difference was considered significant if p < 0.05. ResultsFree fibula flap (FFF) was most commonly used type of the reconstruction of the pediatric mandible. The average maximum deviation for the analyzed cases was 7.7 mm, and the average minimum deviation was −6.09 mm, however without significant differences and the postoperative position of the mandible condyle was comparable to the position designed in the 3DVSP preoperatively. Position of the whole reconstructed mandible by means of individually planned grafts and plates provided comparable position of the ramus and mandible body and no chin deviation as the differences between the pre-operative axial and sagittal angles and their post-operative equivalents were insignificant (p > 0,05). ConclusionsThis study confirms applicability of the 3DVSP in pediatric craniomaxillofacial surgery. Preoperative planning of the osteotomies, grafting technique and production of the individualized guides and implants provides precise tumor resection and immediate reconstruction adjusted to the specific anatomy of the pediatric patients.

Automatic continuous distraction osteogenesis device for hand reconstruction applications

Distraction Osteogenesis (DO) is an emerging technique for reconstruction of bone tissue in different body zones including mandible, tibia, hand, and foot. The application of DO technique in reconstruction of bone tissue has shown promising results compared to conventional reconstruction techniques, including bone grafting, prosthetics, and the vascularized flap. Mechanical distractors, with intermittent manual activation by the user, have been widely used in different reconstruction applications. Recently, automatic devices have been developed and used for enabling reconstruction applications using continuous DO technique. These devices can generate a continuous force while continuously moving the bone segment with high movement accuracy and distraction rate. In the continuous DO technique, by using a continuous force, instead of applying intermittent manual forces generated by the operator, better results in a shorter treatment could be obtained. Previous studies have shown that current automatic devices could positively influence bone tissue regeneration while obtaining promising results in the reconstruction of mandible. In hand reconstruction applications (HRA), only manual and mechanical mechanisms, using discontinuous DO technique, have been developed and used. In this research, an automatic device for HRA, using continuous DO technique, has been designed and developed. The proposed system is capable of generating a continuous distraction force for moving the bone segment in a fully automatic DO process. This novel reconstruction approach can be used for lengthening and reconstruction of different hand bones, including distal, middle, proximal, metacarpal, and carpal bones. In HRA, by using the proposed automatic continuous distractor better results in a shorter treatment period, compared to manual DO solutions, can be achieved

Nanocomposite fibrous scaffold mediated mandible reconstruction and dental rehabilitation: An experimental study in pig model

Mandible reconstruction and dental rehabilitation after trauma or tumor resection represent a serious challenge for maxillofacial surgeons. This study aimed to investigate the bone formation potential of nanocomposite fibrous scaffold (silica-nanohydroxyapatite-gelatin reinforced with poly L-lactic acid yarns - CSF) for delayed Titanium (Ti) implantation, which was compared to autograft (AG) taken from the iliac crest. The grafts were placed in critical-sized mandibular defects in an adult pig model for 6 months followed by dental implant placement for another 3 months. There was complete union and vascularised lamellar bone formation within 6 months. Moreover, the biological processes associated with angiogenesis, bone maturation and remodelling were seen in CSF, which was comparable to AG. Later, when Ti dental implant was placed on newly formed bone, CSF group demonstrated better osseointegration. In short, nanocomposite fibrous scaffold promoted quality bone formation in mandible defect that leads to successful osseointegration, suggesting as a potential candidate for implant-based rehabilitation in clinics in future.

Synchrony in head and neck surgery: Feasibility and outcomes of simultaneous scapular free flap reconstruction.

The scapula free flap is a versatile option in head and neck reconstruction but is less amenable to simultaneous harvest and ablation. Retrospective series (2015-2021) of consecutive scapula flaps. Cases categorized as simultaneous versus sequential, compared for operative time, oncological and patient-reported outcomes. Seventy consecutive scapula free flaps were performed (n= 21 simultaneous, n= 49 sequential). Mandible reconstruction was performed in 51.0% and 61.9% of sequential and simultaneous cases, respectively; 49.0% and 38.1% addressed bony maxillary defects. Simultaneous surgery reduced operative time by 37.9% (151 min, p < 0.00001) and there were fewer tracheostomies performed (p < 0.005). Rates of positive margins and free flap compromise were equivalent (n=1, 4.8% vs. n=2, 4.1%). There was no difference in patient-reported outcomes. This series demonstrates feasibility, efficacy, and outcomes of bony scapula reconstruction of maxillofacial defects comparing simultaneous and sequential approaches. Benefits of the two-team approach are highlighted including decreased operative time.

Mandible reconstruction with free fibula flaps: Accuracy of a cost-effective modified semicomputer-assisted surgery compared with computer-assisted surgery - A retrospective study

A new individualized, cost-effective, modified semi-computer-assisted surgery (MSCAS) concept for free fibular flap mandibular reconstruction is reported and compared with the computer-assisted surgery (CAS) concept.Patients were divided into two groups and retrospectively reviewed. In the MSCAS and CAS groups, intraoperative guides were created using computer-aided design with manual fabrication and computer-aided design and manufacturing, respectively. Differences in specific linear and angular parameters on pre- and postoperative computed tomography scans were calculated for morphometric comparison, and clinical parameters and efficiency were analysed. ResultsEighteen patients (CAS, 7; MSCAS, 11), were included. The morphometric comparison showed no significant differences between the groups. The mean deviation of the mandibular ramus length, body length, width 1 and width 2 was 0.82 ± 0.29 mm, 1.84 ± 0.43 mm, 1.89 ± 0.61 mm and 1.45 ± 0.61 mm in the CAS group versus 1.56 ± 0.54 mm, 1.72 ± 0.33 mm, 2.24 ± 0.55 mm and 2.36 ± 0.50 mm in the MSCAS group (p = 0.7804, p = 0.9997, p = 0.9814 and p = 0.6334). The mean deviation of the sagittal, axial and coronal mandibular angles was 1.56 ± 0.48°, 1.93 ± 0.50° and 2.15 ± 0.72° in the CAS group versus 2.19 ± 0.35°, 1.86 ± 0.35° and 1.94 ± 0.55° in the MSCAS group (p = 0.7594, p = 0.9996 and p = 0.9871). There were no significant differences in clinical parameters, efficiency or postoperative complications between the groups. ConclusionThe accuracy and operative efficiency of the MSCAS concept are comparable to those of the more expensive CAS concept. Therefore, in times of increasing clinical costs, this concept might be an adequate and inexpensive alternative to preoperative CAS.

Biomechanical Evaluation and Factorial Analysis of the 3-Dimensional Printing Self-Designed Metallic Reconstruction Plate for Mandibular Segmental Defect

Reconstruction plates are frequently used to treat mandibular segmental defects. The aim of this study is to compare the biomechanical performance of a 3-dimensional-printed self-designed titanium alloy reconstruction plate with that of the traditional reconstruction plate in mandible reconstruction. The analyzed parameters of the self-designed reconstruction plate, including plate length (100mm and 125mm), plate thickness (2.1, 2.4, and 2.7mm), and bone mass (100, 75, and 50%), were also evaluated. An artificial mandible with anatomical geometry was used to develop the self-designed reconstructed plate. Both invitro experiments and finite element simulations were performed for the biomechanical comparison of the self-designed and traditional reconstruction plates. In finite element analysis, 3 major muscle forces of mandible movement were set as the loading condition, and the displacement of the condyle was fixed in all directions as the boundary condition. The biomechanical performances (stresses in the plate and strains in bone) of the self-designed reconstruction plate were superior to those of the traditional plate. Factorial analysis indicated that plate length and thickness had significant effects on decreasing stresses of the plate and mandibular bone. The self-designed reconstruction plate might have a benefit to reduce the stresses/strains in plate itself and surrounding bone.

Effects of Fiber Cross-Angle Structures on the Mechanical Property of 3D Printed Scaffolds and Performance of Seeded MC3T3-E1 Cells.

The three-dimensional (3D) printing technology combined with bone tissue engineering has become one of the major methods for mandibular reconstruction. However, the key factor retarding mandible reconstruction is the barrier of understanding and achieving the complex 3D gridwork formed by the trabeculae. This study innovatively constructed a low-temperature 3D printing silk fibroin/collagen/hydroxyapatite (SF/COL/HA) composite scaffold with a stable structure and remarkable biocompatibility. We designed three kinds of six-layer scaffolds with mixed fiber cross-angle structures (FCAS) of [0°/90°/0°/90°/0°/90°], [0°/45°/90°/135°/180°/225°] and [0°/30°/60°/90°/120°/150°]. Material properties of these scaffolds such as porosity, water absorption rate, X-ray diffraction, Fourier transform infrared spectroscopy, and compression performance were detected. Then, the MC3T3-E1 cells were seeded on these scaffolds and the adhesion, proliferation, and differentiation were investigated. To be more convincing, the same experiments were performed on another polycaprolactone/hydroxyapatite scaffold. The results suggested that the changes of FCAS affected the mechanical properties of 3D printed scaffolds and performance of seeded cells. Besides, the 90° FCAS significantly enhanced the compressive modulus in two groups and were more conducive to the cell proliferation and osteogenesis, which provided evidence for exploring the influence of FCAS on the properties of scaffolds and the application of two composite scaffolds in tissue regeneration.

Complications in oncologic mandible reconstruction: A comparative study between the osteocutaneous radial forearm and fibula free flap.

The osteocutaneous radial forearm free flap (OC-RFFF) has been proposed as a safe and reliable free flap for head and neck reconstruction with low donor site morbidity. The purpose of this study is to compare the late complications (>30 days) associated with using the OC-RFFF versus the free fibula flap (FFF) for mandibular reconstruction following oncologic segmental resection. We conducted a single-institution, retrospective study composed of patients who underwent oncologic microvascular composite mandibular reconstruction with either the OC-RFFF or FFF. The primary predictor variable was the type of free flap used. The outcome variable was late complication postoperatively (>30 days). A total of 93 patients (28, OC-RFFF and 65, FFF) were analyzed. The majority of patients were male (62%) and with AJCC stage T4a disease (72%). Mean hospital length of stay was comparable between the two flap groups (p= .50). OC-RFFF was associated with more late complications (p= .03) compared to FFF. Nonunion occurred in 10.7% of OC-RFFF and 0% of FFF. Partial or complete flap failure was seen in 7.1% and 0% in the OC-RFFF and FFF, respectively. Two-year disease-free survival was comparable in both groups (p> .05). The results of this study suggest that the rate of nonunion and odds of having a late complication were significantly greater in the OC-RFFF compared to the FFF following oncologic mandibular reconstruction. However, flap success, early complications (<30 days), and length of hospital stay were comparable between the two flaps.

Preclinical study of additive manufactured plates with shortened lengths for complete mandible reconstruction: Design, biomechanics simulation, and fixation stability assessment

BackgroundA combination of short titanium plates fabricated using additive manufacturing (AM) provides multiple advantages for complete mandible reconstruction, such as the minimisation of inherent implant deformation formed during AM and the resulting clinical impact, as well as greater flexibility for surgical operation. However, the biomechanical feasibility of this strategy is still unclear, and therefore needs to be explored. MethodThree different combinations of short mandible reconstruction plates (MRPs) were customised considering implant deformation during the AM process. The resulting biomechanical performance was analysed by finite element analysis (FEA) and compared to a conventional single long MRP. ResultsThe combination of a long plate and a short plate (Design 3 [LL61 mm/RL166 mm]) shows superior biomechanical properties to the conventional single long plate (Design 1 [TL246 mm]) and reveals the most reliable fixation stability among the three designs with short plates. Compared to conventional Design 1, Design 3 provides higher plate safety (maximum tensile stress on plates reduced by 6.3%), lower system fixation instability (relative total displacement reduced by 41.4%), and good bone segment stability (bone segment dislocation below 42.1 μm) under masticatory activities. ConclusionsPreclinical evidence supports the biomechanical feasibility of using short MRPs for complete mandible reconstruction. Furthermore, the results could also provide valuable information when treating other large-sized bone defects using short customised implants, expanding the potential of AM for use in implant applications.

Possible Treatment of Severe Bone Dehiscences Based on 3D Bone Reconstruction—A Description of Treatment Methodology

Gingival recessions constitute serious limitations for effective interdisciplinary periodontal, orthodontic, and implant therapy. A proper bone morphology of the alveolar bone and soft tissues that cover it are interdependent. The regeneration procedures known to date are based on the use of autogenous bone, or its allogeneic, xenogeneic, or alloplastic substitutes. These substitutes are characterized by different osteogenesis potentials. No effective procedure for three-dimensional bone reconstruction for cases in which there is dentition with recessions has been described to date, especially in its vertical dimension. This article presents the patented method of the three-dimensional bone reconstruction of the anterior mandible with preserved dentition when using an allogeneic bone block, and also includes a case report with a 2-year follow-up as an example. Based on clinical observations, it was stated that the intended therapeutic effect was achieved. There was no recession, shallowing of the vestibule, signs of inflammation, or pathological mobility of the teeth in the area undergoing reconstruction. The radiographic images revealed the formation of a new layer of cortical bone on the vestibular side and a certain volume of cancellous bone. No radiological demarcation zone of brightening, which indicates an incomplete adaptation, integration, and reconstruction of the bone block, was found.

A 3D segmentation network of mandible from CT scan with combination of multiple convolutional modules and edge supervision in mandibular reconstruction

Mandibular reconstruction is a very complex surgery that demands removing the tumor, which is followed by reconstruction of the defective mandible. Accurate segmentation of the mandible plays an important role in its preoperative planning. However, there are many segmentation challenges including the connected boundaries of upper and lower teeth, blurred condyle edges, metal artifact interference, and different shapes of the mandibles with tumor invasion (MTI). Those manual or semi-automatic segmentation methods commonly used in clinical practice are time-consuming and have poor effects. The automatic segmentation methods are mainly developed for the mandible without tumor invasion (Non-MTI) rather than MTI and have problems such as under-segmentation. Given these problems, this paper proposed a 3D automatic segmentation network of the mandible with a combination of multiple convolutional modules and edge supervision. Firstly, the squeeze-and-excitation residual module is used for feature optimization to make the network focused more on the mandibular segmentation region. Secondly, the multi atrous convolution cascade module is adapted to implement a multi-scale feature search to extract more detailed features. Considering that most mandibular segmentation networks ignore the boundary information, the loss function combining region loss and edge loss is applied to further improve the segmentation performance. The final experiment shows that the proposed network can segment Non-MTI and MTI quickly and automatically with an average segmentation time of 7.41s for a CT scan. In the meantime, it also has a good segmentation accuracy. For Non-MTI segmentation, the dice coefficient (Dice) reaches 97.98 ± 0.36%, average surface distance (ASD) reaches 0.061 ± 0.016 mm, and 95% Hausdorff distance (95HD) reaches 0.484 ± 0.027 mm. For Non-MTI segmentation, the Dice reaches 96.90 ± 1.59%, ASD reaches 0.162 ± 0.107 mm, and 95HD reaches 1.161 ± 1.034 mm. Compared with other methods, the proposed method has better segmentation performance, effectively improving segmentation accuracy and reducing under-segmentation. It can greatly improve doctor's segmentation efficiency and will have a promising application prospect in mandibular reconstruction surgery in the future.

Primary Reconstruction in Segmental Resection of Mandible-An Outcome Analysis of Different Reconstructive Techniques.

Functional and cosmetic defects in the maxillofacial region may result from trauma, inflammatory disease, benign or malignant tumors. There are several well established reconstructive options for restoring mandibular continuity and function. Traditionally, surgeons have used their past experience to determine the best way to perform the osteotomy, graft harvesting, and graft shaping procedures for mandibular reconstruction. Focus has now shifted to optimize functional and aesthetic outcomes in mandible reconstruction. Refinements in surgical techniques continue to improve patient's quality of life. The purpose of this study was to evaluate the outcome of a range of reconstructive techniques in 20 patients who underwent segmental resection of mandible during the period 2004-2017.

Pediatric Mandibular Reconstruction Using the Vascularized Fibula Free Flap: Functional Outcomes in 34 Consecutive Patients.

The vascularized fibula free flap is a workhorse flap in pediatric mandibular reconstruction. This study aimed to address functional outcomes, complications, and morbidity associated with the fibula resection in a consecutive series of mandibular reconstruction using this technique in skeletally immature patients. Functional outcomes in terms of maximal mouth opening capacity, patient-reported eating ability, occlusion, and gait were retrospectively reviewed in 34 consecutive pediatric patients (18 males, 16 females) who underwent mandibular reconstruction using the vascularized free fibula flap. Data regarding donor and recipient site complications were also retrieved. The mean follow-up period was 50.6 months (range, 12-108 months). The average age was 10.3 years (range, 2-15 years). Underlying pathologies included ossifying fibroma, ameloblastoma, mandibular arteriovenous malformation, fibrous dysplasia, Goldenhar syndrome, dentigerous cyst, mandibular lymphoma, odontogenic fibroma, adenomatoid odontogenic tumor, aneurysmal bone cyst, neurogenic sarcoma, and central giant cell granuloma. Defect length ranged from 8 to 17 cm. Mean return to normal ambulation was achieved 12 days postoperatively. All patients reported ability to eat solids and liquids, with 29 of 34 achieving normal mouth opening. Normal or minimally disturbed occlusion was maintained postoperatively in most patients. Temporomandibular joint ankylosis and condylar displacement were each developed in one patient. Two patients reported gait disturbances that receded after physical therapy. No other major donor site complications, including flexion contracture of the great toe, were identified. The vascularized fibula free flap is reaffirmed to be the criterion standard for mandible reconstruction in pediatric patients, providing satisfactory functional results and adequate adaptation to the growing facial skeleton with minimal sequelae. Complications regarding hallux function may be prevented by assessing the vascularity of the flexor hallucis longus intraoperatively and ensuring tension-free closure of the donor site.