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Free flap surgery is currently the only successful method used by surgeons to reconstruct critical-sized defects of the jaw, and is commonly used in patients who have had bony lesions excised due to oral cancer, trauma, infection or necrosis. However, donor site morbidity remains a significant flaw of this strategy. Various biomaterials have been under investigation in search of a suitable alternative for segmental mandibular defect reconstruction. Hydrogels are group of biomaterials that have shown their potential in various tissue engineering applications, including bone regeneration, both through in vitro and in vivo pre-clinical animal trials. This review discusses different types of hydrogels, their fabrication techniques, 3D printing, their potential for bone regeneration, outcomes, and the limitations of various hydrogels in preclinical models for bone tissue engineering. This review also proposes a modified technique utilizing the potential of hydrogels combined with scaffolds and cells for efficient reconstruction of mandibular segmental defects.

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.

Background Mandibular defects of class I and II, frequently encompassing the mandibular angle, a critical aspect of facial aesthetics, are the most prevalent. However, current techniques for mandibular defect reconstruction exhibit limitations in restoring the mandibular angle and pose intraoperative challenges. There is an urgent need for a simpler, innovative surgical approach to mandibular reconstruction. Methods This study conducted a retrospective analysis of 24 patients treated with the L-shaped iliac crest flap for partial mandibular defect reconstruction at the Department of Oral and Maxillofacial Surgery, School of Stomatology, Wuhan University, from March 2021 to November 2024. Outcomes were evaluated descriptively and included flap survival, operative details, donor-site morbidity, and qualitative assessment of contour restoration. Results In our study, the flap survival rate was 95.83%. At a mean follow-up of 69 weeks, no major donor-site complications (e.g., hernia, chronic pain) were recorded. Based on subjective qualitative assessment by the surgical team and patient feedback, patients exhibited satisfactory recovery in mandibular angle, facial appearance, intraoral morphology, occlusion relationships, and alveolar ridge height. Clinical and radiographic evaluation suggested satisfactory restoration of the mandibular angle contour and adequate bone height for subsequent dental implant placement in patients. Conclusions The L-shaped iliac crest flap concurrently addresses the mandibular body and ramus, utilizing the natural contour of the anterior superior iliac spine to visibly restore the mandibular angle’s shape and fullness. The innovative L-shaped iliac crest flap offers a potential option for restoring craniofacial aesthetics and function in mandibular defect repair in the future. Future prospective comparative studies are warranted to objectively assess its aesthetic and functional benefits relative to established techniques.

Reconstruction of jaw bone defects present a significant problem because of specific aesthetic and functional requirements. Although widely used, the transplantation of standard autograft and allograft materials is still associated with significant constraints. Composite scaffolds, combining advantages of biodegradable polymers with bioceramics, have potential to overcome limitations of standard grafts. Polyethyleneimine could be an interesting novel biocompatible polymer for scaffold construction due to its biocompatibility and chemical structure. To date, there have been no in vivo studies assessing biological properties of hydroxyapatite bioceramics scaffold modified with polyethyleneimine. The aim of this study was to evaluate in vivo effects of composite scaffolds of hydroxyapatite ceramics and poly(lactide-co-glycolide) and novel polyethyleneimine on bone repair in swine’s mandibular defects, and to compare them to conventional bone allograft (BioOss). Scaffolds were prepared using the method of polymer foam template in three steps. Pigs, 3 months old, were used and defects were made in the canine, premolar, and molar area of their mandibles. Four months following the surgical procedure, the bone was analyzed using radiological, histological, and gene expression techniques. Hydroxyapatite ceramics/polyethyleneimine composite scaffold demonstrated improved biological behavior compared to conventional allograft in treatment of swine’s mandibular defects, in terms of bone density and bone tissue histological characteristics.

Adipose stem cell-derived exosomes (ADSC-EXO) have been demonstrated to promote osteogenic differentiation of bone marrow stem cells (BMSCs) and facilitate bone regeneration. The present study aims to investigate the effect of ADSC-EXO-loaded nano-hydroxyapatite/chitosan/poly-lactide-co-glycolide (nHA/CS/PLGA) scaffolds on maxillofacial bone regeneration using tissue engineering. ADSC-EXO was isolated and co-cultured with BMSCs, and the osteogenic differentiation of BMSCs was assessed through the detection of mineralized nodule formation, alkaline phosphatase (ALP) activity, and mRNA expression of COL1A1 and runt-related transcription factor 2 (RUNX2). The nHA/CS/PLGA scaffolds were fabricated and loaded with ADSC-EXO and BMSCs, and these tissue engineering complexes were applied to the maxillofacial bone defect region of rabbits to elucidate their bone regeneration effect. The osteogenic differentiation of BMSCs was markedly enhanced when they were co-cultured with ADSC-EXO. This was evidenced by an increase in the formation of mineralized nodule formation, ALP activity, and mRNA expression of COL1A1 and runt-related transcription factor 2 (RUNX2). In vivo experiments demonstrated that the application of ADSC-EXO and BMSCs loaded nHA/CS/PLGA scaffolds effectively repaired maxillofacial bone defects in rabbits. ADSC-EXO has been demonstrated to promote the osteogenic differentiation of BMSCs. The ADSC-EXO and BMSCs loaded nHA/CS/PLGA scaffolds have been shown to facilitate the regeneration of maxillofacial bone defects. This may serve as a potential therapeutic strategy for large-scale bone defects.

Objective Given the increasing demand for precise and reliable reconstructive techniques in maxillofacial surgery, we try to offer valuable insights for clinicians in selecting optimal fixation methods. Materials and Methods Patients were categorized into miniplate and reconstruction plate groups for accuracy and bone healing comparison. We measured gonial angle, intercondylar, intergonial and anterior-posterior distance for general accuracy and distance of segmental endpoint to the sagittal plane for partial accuracy. The bone healing rate of the two groups was compared with CT images at 3, 6 and 12 months after operation. Result Considering directional indicators, the miniplate group exhibited a wider intercondylar distance than the reconstruction plate group ( p  = 0.029). At 6 months postoperatively, the miniplate group demonstrated a higher bone healing rate compared to the reconstruction plate group, with no significant differences at other time points. Conclusion Over a nearly 5-year review, mandibular reconstruction with vascularized iliac bone flaps showed that reconstruction plates better maintained condylar position accuracy, while miniplates had superior bone healing rates at 6 months. No significant differences were found in other accuracy indices between the two plates. Clinical Relevance Clinicians’ selection of fixation plates frequently depends on personal preference rather than evidence-based criteria. This study compares the precision and postoperative osseous healing outcomes of miniplates and reconstruction plates to provide a more scientifically grounded basis for clinical decision-making.

Objective This study aimed to compare the stress distribution after folded and single-layer fibular reconstruction with implant-supported restoration for Brown Class Ⅱ mandibular defects using finite element analysis (FEA), to provide a theoretical basis for selecting an optimal mandibular reconstruction strategy in clinical practice. Methods A healthy adult female volunteer from Bengbu Medical University underwent spiral computed tomography (CT) scans of the mandible and fibula. The CT data were imported into Mimics 21.0 software to reconstruct three-dimensional models of the intact mandible, dentition, and fibula. These models were further processed in Geomagic Studio 2014, Materialise 3-matic 18.0, and Exocad to establish FEA models of the intact mandible, as well as single-layer (Model A) and folded (Model B) fibular reconstruction with implant-supported restoration for Brown Class Ⅱ mandibular defects. The geometric models were then imported into Ansys 19.0 software for FEA to evaluate biomechanical characteristics and stress distribution patterns on implants, the reconstructed fibula, and surrounding bone tissues were compared between the two reconstruction methods. Results (1) Under identical loading conditions, stress concentration areas in the intact mandible were observed at the bilateral condylar necks, sigmoid notches, mandibular angles, and junctions between the mandibular body and ramus, with the maximum stress (57.627 MPa) located at the affected-side mandibular angle. (2) In Model A and Model B, the maximum stresses in the residual mandible were 82.619 MPa and 80.842 MPa, respectively, both at the affected-side mandibular angle, representing increases of 43.4% and 40.3% compared to the intact mandible (57.627 MPa). (3) The maximum stress in the reconstructed fibula was 65.31 MPa in Model B, which was lower than the 73.922 MPa in Model A. (4) The maximum stresses in implants 1, 2, and 3 were 19.496 MPa, 50.638 MPa, and 78.747 MPa in Model B, and 32.537 MPa, 99.558 MPa, and 123.14 MPa in Model A, all located at the implant necks. Conclusion Compared with the single-layer fibular flap, the folded fibular flap is a superior choice for the reconstruction of Brown Class Ⅱ mandibular defects with subsequent implant restoration.

Bone tissue engineering is a rapidly developing field with potential for the regeneration of craniomaxillofacial (CMF) bones, with 3D printing being a suitable fabrication tool for patient‐specific implants. The CMF region includes a variety of different bones with distinct functions. The clinical implementation of tissue engineering concepts is currently poor, likely due to multiple reasons including the complexity of the CMF anatomy and biology, and the limited relevance of the currently used preclinical models. The ‘recapitulation of a human disease’ is a core requisite of preclinical animal models, but this aspect is often neglected, with a vast majority of studies failing to identify the specific clinical indication they are targeting and/or the rationale for choosing one animal model over another. Currently, there are no suitable guidelines that propose the most appropriate animal model to address a specific CMF pathology and no standards are established to test the efficacy of biomaterials or tissue engineered constructs in the CMF field. This review reports the current clinical scenario of CMF reconstruction, then discusses the numerous limitations of currently used preclinical animal models employed for validating 3D‐printed tissue engineered constructs and the need to reduce animal work that does not address a specific clinical question. We will highlight critical research aspects to consider, to pave a clinically driven path for the development of new tissue engineered materials for CMF reconstruction. Reconstruction of bone defects of the CMF region is a major and difficult surgical intervention. 3D printing is an ideal biofabrication tool to create patient‐specific tissue engineered bone scaffolds. An appropriate pre‐clinical animal model should be based on the targeted clinical indication. Implementing standardised guidelines for preclinical studies can improve translation.

Reconstruction of a mandibular defect is challenging, with high expectations for both functional and esthetic results. Bone morphogenetic protein-2 (BMP-2) is an essential growth factor in osteogenesis, but the efficacy of the BMP-2-based strategy on the bone regeneration of mandibular defects has not been well-investigated. In addition, the underlying mechanisms of BMP-2 that drives the bone formation in mandibular defects remain to be clarified. Here, we utilized BMP-2-loaded hydrogel to augment bone formation in a critical-size mandibular defect model in rats. We found that implantation of BMP-2-loaded hydrogel significantly promoted intramembranous ossification within the defect. The region with new bone triggered by BMP-2 harbored abundant CD31+ endomucin+ type H vessels and associated osterix (Osx)+ osteoprogenitor cells. Intriguingly, the new bone comprised large numbers of skeletal stem cells (SSCs) (CD51+ CD200+) and their multi-potent descendants (CD51+ CD105+), which were mainly distributed adjacent to the invaded blood vessels, after implantation of the BMP-2-loaded hydrogel. Meanwhile, BMP-2 further elevated the fraction of CD51+ CD105+ SSC descendants. Overall, the evidence indicates that BMP-2 may recapitulate a close interaction between functional vessels and SSCs. We conclude that BMP-2 augmented coupling of angiogenesis and osteogenesis in a novel and indispensable way to improve bone regeneration in mandibular defects, and warrants clinical investigation and application.

Purpose The purpose of this study was to evaluate the accuracy of virtual planning using customized surgical devices (VP3D) in fibula free flap mandibular reconstruction. Methods Fourteen patients received VP3D and 16 patients underwent conventional surgery (CS). Virtual planning was compared to postoperative scans using cephalometric and three-dimensional (3D) measurements. Operative times of both VP3D and CS groups were compared. Results Comparisons of cephalometric measurements revealed no significant difference between virtual planning and postoperative scans. 3D analysis demonstrated a high level of virtual planning accuracy. In the VP3D group, total operative time gain was 88 min ( p  < 0.001) and total ischemia time gain was 36 min ( p  = 0.04). Conclusion Virtual surgical planning using customized devices enables ‘tailored’ surgery that is accurate and reliable and results in operative and ischemia time gain. Clinical trial NCT03869723.