Reconstruction of segmental mandibular defects: Current procedures and perspectives

In vivo endocultivation of CAD/CAM hybrid scaffolds in the omentum majus in miniature pigs

PURPOSE

Correction of bony mandibular defects is a challenge in oral and maxillofacial surgery due to aesthetic and functional requirements. This study investigated the potential of a novel hybrid scaffold for bone regeneration and degradation assessment of the ceramic within the omentum majus over 6 months and the extent to which rhBMP-2 as a growth factor, alone or combined with a hydrogel, affects regeneration.

MATERIALS AND METHODS

In this animal study, 10 Göttingen minipigs each had one scaffold implanted in the greater omentum. Five animals had scaffolds loaded with a collagen hydrogel and rhBMP-2, and the other five animals (control group) had scaffolds loaded with rhBMP-2 only. Fluorochrome injections and computed tomography (CT) were performed regularly. After 6 months, the animals were euthanized, and samples were collected for microCT and histological evaluations.

RESULTS

Fluorescent and light microscopic and a CT morphological density evaluation showed continuous bone growth until week 16 in both groups. Regarding the ratio of bone attachment to the Zr02 support struts, the rhBMP-2 loaded collagen hydrogel group showed with 63% a significantly higher attachment (p > 0.001) than the rhBMP-2 control group (49%).

CONCLUSION

In this study, bone growth was induced in all omentum majus specimens until post-operative week 16. Furthermore, hydrogel and rhBMP-2 together resulted in better bone-scaffold integration than rhBMP-2 alone. Further studies should investigate whether implantation of the scaffolds in the jaw after an appropriate period of bone regeneration leads to a stable situation and the desired results.

Evaluation of stiffness-matched, 3D-printed, NiTi mandibular graft fixation in an ovine model

BACKGROUND

Manually bent, standard-of-care, Ti-6Al-4V, mandibular graft fixation devices are associated with a significant post-operative failure rate. These failures require the patient to endure stressful and expensive re-operation. The approach recommended in this report demonstrates the optimization of graft fixation device mechanical properties via "stiffness-matching" by varying the fixation device's location, shape, and material composition through simulation of the device's post-operative performance. This provides information during pre-operative planning that may avoid future device failure. Optimized performance may combine translation of all loading into compression of the bone graft with the adjacent bone segments and elimination or minimization of post-healing interruption of normal stress-strain (loading) trajectories.

RESULTS

This study reports a sheep mandibular graft model where four animals received virtually optimized, experimental nickel-titanium (NiTi) fixation plates fabricated using laser beam powder bed fusion (LPBF) additive manufacturing (AM). The last animal, our control, received a standard-of-care, manually bent, Ti-6Al-4V (aka Ti64) fixation plate. A 17.5-mm mandibular graft healed completely in all four animals receiving the experimental device. Experimental NiTi-implanted sheep experienced mandibular bone healing and restoration. The Ti64 plate, in the control animal, fractured and dislocated shortly after being implanted.

CONCLUSION

The use of stiffness-matched implants, by means of plate material (NiTi) and geometry (porosity) enhanced bone healing and promoted better load transfer to the healed bone when compared to the bulk Ti64 found in the fixation plate that the Control animal received. The design technique and screw orientation and depth planning improved throughout the study leading to more rapid healing. The large animal model reported here provides data useful for a follow-on clinical trial.

Long-term outcomes in virtual surgical planning for mandibular reconstruction: A cost-effectiveness analysis

OBJECTIVE

This study is an economic evaluation comparing virtual surgical planning (VSP) utilization to free hand mandibular reconstruction (FHR) for advanced oral cavity cancer, for which the cost effectiveness remains poorly understood. The proposed clinical benefits of VSP must be weighed against the additional upfront costs.

METHODS

A Markov decision analysis model was created for VSP and FHR based on literature review and institutional data over a 35-year time horizon. Model parameters were derived and averaged from systematic review and institutional experience. VSP cost and surgical time saving was incorporated. We accounted for long-term risks including cancer recurrence and hardware failure/exposure. We calculated cost in US dollars and effectiveness in quality-adjusted-life-years (QALYs). A health care perspective was adopted, discounting costs and effectiveness at 3%/year. Deterministic and probabilistic sensitivity analyses tested model robustness.

RESULTS

In the base case scenario, total VSP strategy cost was $49,498 with 8.37 QALYs gained while FHR cost was $42,478 with 8.27 QALY gained. An incremental cost-effectiveness ratio (ICER), or the difference in cost/difference in effectiveness, for VSP was calculated at $68,382/QALY gained. VSP strategy favorability was sensitive to variations of patient age at diagnosis and institutional VSP cost with one-way sensitivity analysis. VSP was less economically favorable for patients >75.5 years of age or for institutional VSP costs >$10,745. In a probabilistic sensitivity analysis, 55% of iterations demonstrated an ICER value below a $100,000/QALY threshold.

CONCLUSIONS/RELEVANCE

VSP is economically favorable compared to FHR in patients requiring mandibular reconstruction for advanced oral cancer, but these results are sensitive to the patient's age at diagnosis and the institutional VSP cost. Our results do not suggest if one "should or should not" use VSP, rather, emphasizes the need for patient selection regarding which patients would most benefit from VSP when evaluating quality of life and long-term complications. Further studies are necessary to demonstrate improved long-term risk for hardware failure/exposure in VSP compared to FHR.

MicroRNA-29c-tetrahedral framework nucleic acids: Towards osteogenic differentiation of mesenchymal stem cells and bone regeneration in critical-sized calvarial defects

Certain miRNAs, notably miR29c, demonstrate a remarkable capacity to regulate cellular osteogenic differentiation. However, their application in tissue regeneration is hampered by their inherent instability and susceptibility to degradation. In this study, we developed a novel miR29c delivery system utilising tetrahedral framework nucleic acids (tFNAs), aiming to enhance its stability and endocytosis capability, augment the efficacy of miR29c, foster osteogenesis in bone marrow mesenchymal stem cells (BMSCs), and significantly improve the repair of critical-sized bone defects (CSBDs). We confirmed the successful synthesis and biocompatibility of sticky ends-modified tFNAs (stFNAs) and miR29c-modified stFNAs (stFNAs-miR29c) through polyacrylamide gel electrophoresis, microscopy scanning, a cell counting kit-8 assay and so on. The mechanism and osteogenesis effects of stFNAs-miR29c were explored using immunofluorescence staining, western blotting, and reserve transcription quantitative real-time polymerase chain reaction. Additionally, the impact of stFNAs-miR29c on CSBD repair was assessed via micro-CT and histological staining. The nano-carrier, stFNAs-miR29c was successfully synthesised and exhibited exemplary biocompatibility. This nano-nucleic acid material significantly upregulated osteogenic differentiation-related markers in BMSCs. After 2 months, stFNAs-miR29c demonstrated significant bone regeneration and reconstruction in CSBDs. Mechanistically, stFNAs-miR29c enhanced osteogenesis of BMSCs by upregulating the Wnt signalling pathway, contributing to improved bone tissue regeneration. The development of this novel nucleic acid nano-carrier, stFNAs-miR29c, presents a potential new avenue for guided bone regeneration and bone tissue engineering research.

Bioengineering from the laboratory to clinical translation in oral and maxillofacial reconstruction

Background

Conventional techniques used in oral and maxillofacial reconstruction focus mainly on utilizing autologous tissues that have unquestionably improved function and esthetics for many patients, worldwide. However, the success depends on countless factors such as: donor and recipient sites conditions, patient's medical history, surgeon's experience, restricted availability of high-quality autogenous tissues or stem cells, and increased surgical cost and time.

Materials and Methods

Lately, teaming researchers, scientists, surgeons, and engineers, to address these limitations, have allowed tremendous progress in recombinant protein therapy, cell-based therapy, and gene therapy.

Results

Over the past few years, biomedical engineering has been evolving from the laboratory to clinical applications, for replacement of damaged body tissues due to trauma, cancer, congenital or acquired disorders.

Conclusions

This review provides an outlook on the content, benefits, recent advances, limitations, and future expectations of biomedical engineering for salivary glands, oral mucosa, dental structures, and maxillofacial reconstruction.

Reconstruction of Segmental Mandibular Defects with Double-Barrel Fibula Flap and Osseo-Integrated Implants: A Systematic Review

Background: Mandibular defects resulting from oncological treatment pose significant aesthetic and functional challenges due to the involvement of bone and soft tissues. Immediate reconstruction is crucial to address complications such as malocclusion, mandibular deviation, temporomandibular joint (TMJ) changes, and soft tissue retraction. These issues can lead to functional impairments, including difficulties in chewing, swallowing, and speech. The fibula flap is widely used for mandibular reconstruction due to its long bone segment and robust vascular supply, though it may not always provide adequate bone height for optimal dental rehabilitation. This systematic review aims to determine if the double-barreled fibula flap (DBFF) configuration is a viable alternative for mandibular reconstruction and to evaluate the outcomes of dental implants placed in this type of flap. Materials and Methods: This study adhered to the Cochrane Collaboration criteria and PRISMA guidelines and was registered on the International Platform of Registered Systematic Review and Meta-Analysis Protocols Database (INPLASY2023120026). We included clinical studies published in English, Spanish, or French that focused on adult patients undergoing segmental mandibulectomy followed by DBFF reconstruction and dental rehabilitation. Data sources included Medline/PubMed, the Cochrane Library, EMBASE, Scopus, and manual searches. Two reviewers independently screened and selected studies, with discrepancies resolved by a third reviewer. Data extraction captured variables such as publication year, patient demographics, number of implants, follow-up duration, flap survival, implant failure, and aesthetic outcomes. The risk of bias was assessed using the JBI appraisal tool, and the certainty of evidence was evaluated using the GRADE approach. Results: A total of 17 clinical studies were included, evaluating 245 patients and 402 dental implants. The average patient age was 43.7 years, with a mean follow-up period of 34.3 months. Flap survival was high, with a 98.3% success rate and only four flap losses. The implant failure rate was low at 1.74%. Esthetic outcomes were varied, with only three studies using standardized protocols for evaluation. The overall certainty of evidence for flap survival was moderate, low for implant failure, and very low for aesthetics due to the subjective nature of assessments and variability in reporting. Conclusions: The primary limitations of the evidence included in this review are the observational design of the studies, leading to an inherent risk of bias, inconsistency in reporting methods, and imprecision in outcome measures. Additionally, the subjective nature of aesthetic evaluations and the variability in assessment tools further limit the reliability of the findings. The DBFF technique demonstrates excellent outcomes for mandibular reconstruction, with high flap survival and low implant failure rates, making it a viable option for dental rehabilitation. However, the evidence for aesthetic outcomes is less certain, highlighting the need for more rigorous and standardized research. This review supports the DBFF as a good alternative for mandibular reconstruction with successful dental implant integration, although further studies are needed to enhance the reliability of aesthetic evaluations.

Perioperative pain management after scapular tip free flap harvesting for head and neck reconstruction using mini-catheters to inject the local anesthetic

PURPOSE

Although functional and esthetic results after the use of a scapular tip free flap (STFF) in head and neck reconstruction, and the related donor-site morbidity, have been extensively described, data regarding acute postoperative donor-site pain management are lacking. Purpose of this study is to explore the use of mini-catheters to administer local anesthetics for donor-site pain management after reconstruction using STFF.

METHODS

Patients who underwent head and neck reconstruction using a STFF were prospectively enrolled and, through a perineural catheter placed in the donor site during the surgical procedure, a bolus of chirochaine was injected before the patient regained consciousness and at 8, 16, and 24 h postoperatively. Before and 40 min after each dose administration, donor-site pain on a numerical rating scale (NRS; 0-10) was evaluated.

RESULTS

Study population consisted of 20 patients (40-88 years). At 8 h, the pain scores before and after the injection were 0-10 (mean 3.35) and 0-5 (mean 1.25), respectively. At 16 h, the pain scores before and after the injection were 0-8 (mean 2.55) and 0-4 (mean 0.55), respectively. At 24 h, the pain scores before and after the injection were 0-8 (mean 1.30) and 0-4 (mean 0.30), respectively.

CONCLUSION

Statistical analysis confirmed a significant difference between the pain scores before and after administration at 8, 16, and 24 h (p < 0.001, p < 0.001, and p = 0.003, respectively). Mini-catheters for local anesthetic administration represent an effective strategy for pain control after STFF harvesting for head and neck reconstruction.

The Reconstruction of Mandible Defects in War Injuries: Systematic Review and Meta-Analysis

Study Design

Systematic Review and Meta-Analysis.

Objective

There has been an increasing trend in maxillofacial injuries associated with combat trauma. Within the maxillofacial complex, the mandible is the most likely structure to be damaged during combat. The structural deficits as a result can be reconstructed with many options. These include vascularised bone grafts (VBGs), non-vascularised bone grafts (NVBGs), alloplastic implants, reconstruction bars and distraction osteogenesis. This study aimed to determine the common modality and efficacy of mandibular reconstruction in combat trauma-related defects.

Methods

A literature search was conducted on Pubmed, Prospero, Dynamed, DARE, EMBASE, COCHRANE and BMJ databases.

Results

A total of six articles met the inclusion criteria identifying 165 patients requiring mandibular reconstruction. Non-vascularised iliac bone graft (n = 137) was the most common method followed by ileac crest bone chips harvest using Dacron urethran osteomesh tray (n = 24) and frontoparietal grafts (n = 4). Meta-analysis of five out of six trials demonstrated an overall success rate of 85% (95% CI 79-90; I2 = 59%). A total of 13% (n = 22) of reconstructions failed either completely or partially and 21% (n = 34) of patients suffered postoperative complications.

Conclusions

NVBGs are a practical, cost-effective and favourable method of war zone management of mandibular defects with success rates comparable to those reported in the civilian literature. However, general trauma principles take precedence to rule out life-threatening injuries. Due consideration of patient factors, surgical factors, and available resources are required in the first-line management of combat-related mandibular defects.

A Preclinical Trial Protocol Using an Ovine Model to Assess Scaffold Implant Biomaterials for Repair of Critical-Sized Mandibular Defects

The present work describes a preclinical trial (in silico, in vivo and in vitro) protocol to assess the biomechanical performance and osteogenic capability of 3D-printed polymeric scaffolds implants used to repair partial defects in a sheep mandible. The protocol spans multiple steps of the medical device development pipeline, including initial concept design of the scaffold implant, digital twin in silico finite element modeling, manufacturing of the device prototype, in vivo device implantation, and in vitro laboratory mechanical testing. First, a patient-specific one-body scaffold implant used for reconstructing a critical-sized defect along the lower border of the sheep mandible ramus was designed using on computed-tomographic (CT) imagery and computer-aided design software. Next, the biomechanical performance of the implant was predicted numerically by simulating physiological load conditions in a digital twin in silico finite element model of the sheep mandible. This allowed for possible redesigning of the implant prior to commencing in vivo experimentation. Then, two types of polymeric biomaterials were used to manufacture the mandibular scaffold implants: poly ether ether ketone (PEEK) and poly ether ketone (PEK) printed with fused deposition modeling (FDM) and selective laser sintering (SLS), respectively. Then, after being implanted for 13 weeks in vivo, the implant and surrounding bone tissue was harvested and microCT scanned to visualize and quantify neo-tissue formation in the porous space of the scaffold. Finally, the implant and local bone tissue was assessed by in vitro laboratory mechanical testing to quantify the osteointegration. The protocol consists of six component procedures: (i) scaffold design and finite element analysis to predict its biomechanical response, (ii) scaffold fabrication with FDM and SLS 3D printing, (iii) surface treatment of the scaffold with plasma immersion ion implantation (PIII) techniques, (iv) ovine mandibular implantation, (v) postoperative sheep recovery, euthanasia, and harvesting of the scaffold and surrounding host bone, microCT scanning, and (vi) in vitro laboratory mechanical tests of the harvested scaffolds. The results of microCT imagery and 3-point mechanical bend testing demonstrate that PIII-SLS-PEK is a promising biomaterial for the manufacturing of scaffold implants to enhance the bone-scaffold contact and bone ingrowth in porous scaffold implants. MicroCT images of the harvested implant and surrounding bone tissue showed encouraging new bone growth at the scaffold-bone interface and inside the porous network of the lattice structure of the SLS-PEK scaffolds.

Advances in reparative materials for infectious bone defects and their applications in maxillofacial regions

Infectious bone defects are characterized by the partial loss or destruction of bone tissue resulting from bacterial contaminations subsequent to diseases or external injuries. Traditional bone transplantation and clinical methods are insufficient in meeting the treatment demands for such diseases. As a result, researchers have increasingly focused on the development of more sophisticated biomaterials for improved therapeutic outcomes in recent years. This review endeavors to investigate specific reparative materials utilized for the treatment of infectious bone defects, particularly those present in the maxillofacial region, with a focus on biomaterials capable of releasing therapeutic substances, functional contact biomaterials, and novel physical therapy materials. These biomaterials operate via heightened antibacterial or osteogenic properties in order to eliminate bacteria and/or stimulate bone cells regeneration in the defect, ultimately fostering the reconstitution of maxillofacial bone tissue. Based upon some successful applications of new concept materials in bone repair of other parts, we also explore their future prospects and potential uses in maxillofacial bone repair later in this review. We highlight that the exploration of advanced biomaterials holds promise in establishing a solid foundation for the development of more biocompatible, effective, and personalized treatments for reconstructing infectious maxillofacial defects.

Additively manufactured bioceramic scaffolds based on triply periodic minimal surfaces for bone regeneration

The study focused on the effects of a triply periodic minimal surface (TPMS) scaffolds, varying in porosity, on the repair of mandibular defects in New Zealand white rabbits. Four TPMS configurations (40%, 50%, 60%, and 70% porosity) were fabricated with β-tricalcium phosphate bioceramic via additive manufacturing. Scaffold properties were assessed through scanning electron microscopy and mechanical testing. For proliferation and adhesion assays, mouse bone marrow stem cells (BMSCs) were cultured on these scaffolds. In vivo, the scaffolds were implanted into rabbit mandibular defects for 2 months. Histological staining evaluated osteogenic potential. Moreover, RNA-sequencing analysis and RT-qPCR revealed the significant involvement of angiogenesis-related factors and Hippo signaling pathway in influencing BMSCs behavior. Notably, the 70% porosity TPMS scaffold exhibited optimal compressive strength, superior cell proliferation, adhesion, and significantly enhanced osteogenesis and angiogenesis. These findings underscore the substantial potential of 70% porosity TPMS scaffolds in effectively promoting bone regeneration within mandibular defects.

Titanium Alloy Implants with Lattice Structures for Mandibular Reconstruction

In recent years, the field of mandibular reconstruction has made great strides in terms of hardware innovations and their clinical applications. There has been considerable interest in using computer-aided design, finite element modelling, and additive manufacturing techniques to build patient-specific surgical implants. Moreover, lattice implants can mimic mandibular bone's mechanical and structural properties. This article reviews current approaches for mandibular reconstruction, their applications, and their drawbacks. Then, we discuss the potential of mandibular devices with lattice structures, their development and applications, and the challenges for their use in clinical settings.

Biomechanical feasibility of non-locking system in patient-specific mandibular reconstruction using fibular free flaps

Mandibular reconstruction with free fibular flaps is frequently used to restore segmental defects. The osteosythesis, including locking and non-locking plate/screw systems, is essential to the mandibular reconstruction. Compared with the non-locking system that requires good adaption between plate and bone, the locking system appears to present a better performance by locking the plate to fixation screws. However, it also brings about limitations on screw options, a higher risk of screw failure, and difficulties in screw placement. Furthermore, its superiority is undermined by the advancing of patient-specific implant design and additive manufacturing. A customized plate can be designed and fabricated to accurately match the mandibular contour for patient-specific mandibular reconstruction. Consequently, the non-locking system seems more practicable with such personalized plates, and its biomechanical feasibility ought to be estimated. Finite element analyses of mandibular reconstruction assemblies were conducted for four most common segmental mandibular reconstructions regarding locking and non-locking systems under incisal biting and right molars clenching, during which the influencing factor of muscles' capacity was introduced to simulate the practical loadings after mandibular resection and reconstruction surgeries. Much higher, somewhat lower, and similar maximum von Mises stresses are separately manifested by the patient-specific mandibular reconstruction plate (PSMRP), fixation screws, and reconstructed mandible with the non-locking system than those with the locking system. Equivalent maximum displacements are identified between PSMRPs, fixation screws, and reconstructed mandibles with the non-locking and locking system in all four reconstruction types during two masticatory tasks. Parallel maximum and minimum principal strain distributions are shared by the reconstructed mandibles with the non-locking and locking system in four mandibular reconstructions during both occlusions. Conclusively, it is feasible to use the non-locking system in case of patient-specific mandibular reconstruction with fibular free flaps based on the adequate safety, comparable stability, and analogous mechanobiology it presents compared with the locking system in a more manufacturable and economical way.

β-TCP from 3D-printed composite scaffolds acts as an effective phosphate source during osteogenic differentiation of human mesenchymal stromal cells

Introduction: Human bone marrow-derived mesenchymal stromal cells (hBM-MSCs) are often combined with calcium phosphate (CaP)-based 3D-printed scaffolds with the goal of creating a bone substitute that can repair segmental bone defects. In vitro, the induction of osteogenic differentiation traditionally requires, among other supplements, the addition of β-glycerophosphate (BGP), which acts as a phosphate source. The aim of this study is to investigate whether phosphate contained within the 3D-printed scaffolds can effectively be used as a phosphate source during hBM-MSC in vitro osteogenesis. Methods: hBM-MSCs are cultured on 3D-printed discs composed of poly (lactic-co-glycolic acid) (PLGA) and β-tricalcium phosphate (β-TCP) for 28 days under osteogenic conditions, with and without the supplementation of BGP. The effects of BGP removal on various cellular parameters, including cell metabolic activity, alkaline phosphatase (ALP) presence and activity, proliferation, osteogenic gene expression, levels of free phosphate in the media and mineralisation, are assessed. Results: The removal of exogenous BGP increases cell metabolic activity, ALP activity, proliferation, and gene expression of matrix-related (COL1A1, IBSP, SPP1), transcriptional (SP7, RUNX2/SOX9, PPARγ) and phosphate-related (ALPL, ENPP1, ANKH, PHOSPHO1) markers in a donor dependent manner. BGP removal leads to decreased free phosphate concentration in the media and maintained of mineral deposition staining. Discussion: Our findings demonstrate the detrimental impact of exogenous BGP on hBM-MSCs cultured on a phosphate-based material and propose β-TCP embedded within 3D-printed scaffold as a sufficient phosphate source for hBM-MSCs during osteogenesis. The presented study provides novel insights into the interaction of hBM-MSCs with 3D-printed CaP based materials, an essential aspect for the advancement of bone tissue engineering strategies aimed at repairing segmental defects.

Biomechanical evaluation of additively manufactured patient-specific mandibular cage implants designed with a semi-automated workflow: A cadaveric and retrospective case study

OBJECTIVE

Mandibular reconstruction using patient-specific cage implants is a promising alternative to the vascularized free flap reconstruction for nonirradiated patients with adequate soft tissues, or for patients whose clinical condition is not conducive to microsurgical reconstruction. This study aimed to assess the biomechanical performance of 3D printed patient-specific cage implants designed with a semi-automated workflow in a combined cadaveric and retrospective case series study.

METHODS

We designed cage implants for two human cadaveric mandibles using our previously developed design workflow. The biomechanical performance of the implants was assessed with the finite element analysis (FEA) and quasi-static biomechanical testing. Digital image correlation (DIC) was used to measure the full-field strains and validate the FE models by comparing the distribution of maximum principal strains within the bone. The retrospective study of a case series involved three patients, each of whom was treated with a cage implant of similar design. The biomechanical performance of these implants was evaluated using the experimentally validated FEA under the scenarios of both mandibular union and nonunion.

RESULTS

No implant or screw failure was observed prior to contralateral bone fracture during the quasi-static testing of both cadaveric mandibles. The FEA and DIC strain contour plots indicated a strong linear correlation (r = 0.92) and a low standard error (SE=29.32με), with computational models yielding higher strain values by a factor of 2.7. The overall stresses acting on the case series' implants stayed well below the yield strength of additively manufactured (AM) commercially pure titanium, when simulated under highly strenuous chewing conditions. Simulating a full union between the graft and remnant mandible yielded a substantial reduction (72.7±1.5%) in local peak stresses within the implants as compared to a non-bonded graft.

CONCLUSIONS

This study shows the suitability of the developed semi-automated workflow in designing patient-specific cage implants with satisfactory mechanical functioning under demanding chewing conditions. The proposed workflow can aid clinical engineers in creating reconstruction systems and streamlining pre-surgical planning. Nevertheless, more research is still needed to evaluate the osteogenic potential of bone graft insertions.

Hydrogels for Oral Tissue Engineering: Challenges and Opportunities

Oral health is crucial to daily life, yet many people worldwide suffer from oral diseases. With the development of oral tissue engineering, there is a growing demand for dental biomaterials. Addressing oral diseases often requires a two-fold approach: fighting bacterial infections and promoting tissue growth. Hydrogels are promising tissue engineering biomaterials that show great potential for oral tissue regeneration and drug delivery. In this review, we present a classification of hydrogels commonly used in dental research, including natural and synthetic hydrogels. Furthermore, recent applications of these hydrogels in endodontic restorations, periodontal tissues, mandibular and oral soft tissue restorations, and related clinical studies are also discussed, including various antimicrobial and tissue growth promotion strategies used in the dental applications of hydrogels. While hydrogels have been increasingly studied in oral tissue engineering, there are still some challenges that need to be addressed for satisfactory clinical outcomes. This paper summarizes the current issues in the abovementioned application areas and discusses possible future developments.

The Role of Imaging in Mandibular Reconstruction with Microvascular Surgery

Imaging plays a critical role in the diagnosis, staging, and management of segmental mandibular defects. Imaging allows mandibular defects to be classified which aids in microvascular free flap reconstruction. This review serves to complement the surgeon's clinical experience with image-based examples of mandibular pathology, defect classification systems, reconstruction options, treatment complications, and Virtual Surgical Planning.

Reconstruction of Acquired Segmental Mandibular Defects Using Pedicled Mandibular Muscle Flap and Evaluation of Speech Function and Aesthetic Outcomes

PURPOSE

The purpose of this study was to investigate the clinical effect of pedicled mandibular osteomuscular flap in the reconstouring of repair of acquired segmental mandibular defects.

PATIENTS AND METHODS

Thirteen patients with acquired segmental mandibular defects requiring secondary repair were included into the study. Pedicled mandibular osteomuscular flap was applied with strong internal fixation to repair the mandibular defects. The patients' speech, swallowing function, and aesthetic changes were evaluated upon follow-up.

RESULTS

The flaps were viable in all patients. Average speech function score was 7.6±0.6. All patients had a drinking test rating of grade I or II with good masticatory efficiency. The postoperative self-assessment Visual Analog Scale score of appearance was 7.8±0.8.

CONCLUSIONS

Pedicled mandibular osteomuscular flap is a viable choice in the secondary repair and reconstruction of mandibular acquired segmental defects. This flap could achieve better oral function with good aesthetic results.

Advanced Hydrogel systems for mandibular reconstruction

Mandibular defect becomes a prevalent maxillofacial disease resulting in mandibular dysfunctions and huge psychological burdens to the patients. Considering the routine presence of oral contaminations and aesthetic restoration of facial structures, the current clinical treatments are however limited, incapable to reconstruct the structural integrity and regeneration, spurring the need for cost-effective mandibular tissue engineering. Hydrogel systems possess great merit for mandibular reconstruction with precise involvement of cells and bioactive factors. In this review, current clinical treatments and distinct mode(s) of mandible formation and pathological resorption are summarized, followed by a review of hydrogel-related mandibular tissue engineering, and an update on the advanced fabrication of hydrogels with improved mechanical property, antibacterial ability, injectable form, and 3D bioprinted hydrogel constructs. The exploration of advanced hydrogel systems will lay down a solid foundation for a bright future with more biocompatible, effective, and personalized treatment in mandibular reconstruction.

Aesthetic Reconstruction of Onco-surgical Mandibular Defects Using Free Fibular Flap with and without CAD/CAM Customized Osteotomy Guide: A Randomized Controlled Clinical Trial

BACKGROUND

Reconstruction of mandibular defects following ablative surgery remains a challenge even for experienced surgeons. Virtual planning and guided surgery, including computer-aided design/computer-aided manufacturing (CAD/CAM), afford optimized ways by which to plan complex surgery. This study aimed to evaluate and compare aesthetic outcome and surgical efficiency of free fibular flap (FFF) with and without CAD/CAM customized osteotomy guide (COG) for reconstruction of onco-surgical mandibular defects.

METHODS

Twenty-two patients indicated for segmental mandibulectomy were randomly assigned to either CAD/CAM with COG group or that without COG- Model based reconstruction (MB group) at a 1:1 ratio. Aesthetic outcomes were evaluated by means of morphometric assessment and comparison for each differential area (DAr) and angle (DAn) in the affected side to the contralateral side of the mandible using computerized digital imaging analysis (CDIA) based on the post-operative 3D CT-scan. Subjective evaluation was performed using the Visual Analogue Scale (VAS) and Patient's Satisfaction Score (PSS). Surgical efficiency was a secondary outcome and evaluated as total operative time and ischemia time.

RESULTS

The mean sagittal DAr was significantly lower in the COG group (277.28 ± 127.05 vs. 398.67 ± 139.10 mm², P = 0.045). Although there was an improvement in the axial DAr (147.61 ± 55.42 vs. 183.68 ± 72.85 mm²), the difference was not statistically significant (P = 0.206). The mean differences (Δ) in both sagittal and coronal DAn were significantly lower in the COG group than in the MB group (6.11 ± 3.46 and 1.77 ± 1.12° vs. 9.53 ± 4.17 and 3.44 ± 2.34°), respectively. There were no statistically significant differences in the axial DAn between the two groups (P = 0.386). The PSS was significantly higher in the COG group, reflecting better aesthetic satisfaction than in the MB group (P = 0.041). The total operation and ischemia time were significantly shorter in favor of the COG group with a mean of (562.91 ± 51.22, 97.55 ± 16.80 min vs. 663.55 ± 53.43, 172.45 ± 21.87 min), respectively.

CONCLUSION

The CAD/CAM with COG is more reliable and highly valuable in enhancing aesthetic outcomes and surgical efficiency of mandibular reconstruction by FFF compared to that without COG (MB reconstruction).

TRIAL REGISTRATION

This trial was registered at ClinicalTrials.gov .

REGISTRATION NUMBER

NCT03757273. Registration date: 28/11/2018.

Standardized and axially vascularized calcium phosphate-based implants for segmental mandibular defects: A promising proof of concept

The reconstruction of massive segmental mandibular bone defects (SMDs) remains challenging even today; the current gold standard in human clinics being vascularized bone transplantation (VBT). As alternative to this onerous approach, bone tissue engineering strategies have been widely investigated. However, they displayed limited clinical success, particularly in failing to address the essential problem of quick vascularization of the implant. Although routinely used in clinics, the insertion of intrinsic vascularization in bioengineered constructs for the rapid formation of a feeding angiosome remains uncommon. In a clinically relevant model (sheep), a custom calcium phosphate-based bioceramic soaked with autologous bone marrow and perfused by an arteriovenous loop was tested to regenerate a massive SMD and was compared to VBT (clinical standard). Animals did not support well the VBT treatment, and the study was aborted 2 weeks after surgery due to ethical and animal welfare considerations. SMD regeneration was successful with the custom vascularized bone construct. Implants were well osseointegrated and vascularized after only 3 months of implantation and totally entrapped in lamellar bone after 12 months; a healthy yellow bone marrow filled the remaining space. STATEMENT OF SIGNIFICANCE: Regenerative medicine struggles with the generation of large functional bone volume. Among them segmental mandibular defects are particularly challenging to restore. The standard of care, based on bone free flaps, still displays ethical and technical drawbacks (e.g., donor site morbidity). Modern engineering technologies (e.g., 3D printing, digital chain) were combined to relevant surgical techniques to provide a pre-clinical proof of concept, investigating for the benefits of such a strategy in bone-related regenerative field. Results proved that a synthetic-biologics-free approach is able to regenerate a critical size segmental mandibular defect of 15 cm³ in a relevant preclinical model, mimicking real life scenarii of segmental mandibular defect, with a full physiological regeneration of the defect after 12 months.

Controlled Release of Bone Morphogenetic Protein-2 Augments the Coupling of Angiogenesis and Osteogenesis for Accelerating Mandibular Defect Repair

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.

Hydrogel: A Potential Material for Bone Tissue Engineering Repairing the Segmental Mandibular Defect

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.

Effectiveness of Resective Surgery in Complex Ameloblastoma of the Jaws: A Retrospective Multicenter Observational Study

Ameloblastoma is a rare, benign, odontogenic tumor of epithelial origin, characterized by locally aggressive, expansive growth. Treatment is controversial due to the risk of relapse. The aim of this multicenter retrospective study was to evaluate the effectiveness of complete resection in cases of complex ameloblastoma, which is considered at a higher risk of recurrence. Patients who met at least one of these criteria were included: recurrence, soft-tissue involvement, complete erosion of internal/external cortical walls with involvement of the inferior margin of the mandible, and invasion of the maxillary sinus or nasal cavity. Demographic data, tumor site, type of surgery, histological features, and follow-up information were collected for each patient. The cohort included 55 patients with a mean follow-up of 108 ± 66 months. A multivariate logistic model was used to evaluate variables independently associated with relapse. There were six soft-tissue or maxillary sinus relapses, with a recurrence rate of 10.9%. Most of them arose in patients previously treated. The statistical analysis identified the maxillary location as a fundamental relapse risk factor. En bloc resection with large surgical safety margins seemed to be effective in preventing the relapses. However, complete resection was less effective in preventing recurrences in the soft tissues or maxillary sinus.

A Novel Design Method of Gradient Porous Structure for Stabilized and Lightweight Mandibular Prosthesis

Compared to conventional prostheses with homogenous structures, a stress-optimized functionally gradient prosthesis will better adapt to the host bone due to its mechanical and biological advantages. Therefore, this study aimed to investigate the damage resistance of four regular lattice scaffolds and proposed a new gradient algorithm for stabilized and lightweight mandibular prostheses. Scaffolds with four configurations (regular hexahedron, regular octahedron, rhombic dodecahedron, and body-centered cubic) having different porosities underwent finite element analysis to select an optimal unit cell. Meanwhile, a homogenization algorithm was used to control the maximum stress and increase the porosity of the scaffold by adjusting the strut diameters, thereby avoiding fatigue failure and material wastage. Additionally, the effectiveness of the algorithm was verified by compression tests. The results showed that the load transmission capacity of the scaffold was strongly correlated with both configuration and porosity. Scaffolds with regular hexahedron unit cells can withstand stronger loads at the same porosity. The optimized gradient scaffold showed higher porosity and lower maximum stress than the target stress value, and the compression tests also confirmed the simulation results. A mandibular prosthesis was established using a regular hexahedron unit cell, and the strut diameters were gradually changed according to the proposed algorithm and the simulation results. Compared with the initial homogeneous prosthesis, the optimized gradient prosthesis reduced the maximum stress by 24.48% and increased the porosity by 6.82%, providing a better solution for mandibular reconstruction.

Novel Design and Optimization of Porous Titanium Structure for Mandibular Reconstruction

A porous material is considered to be a potential material that can be used to repair bone defects. However, the methods of designing of a highly porous structure within the allowable stress range remain to be researched. Therefore, this study was aimed at presenting a method for generating a three-dimensional tetrahedral porous structure characterized by low peak stress and high porosity for the reconstruction of mandibular defects. Firstly, the initial tetrahedral porous structure was fabricated with the strut diameters set to 0.4 mm and a mean cell size of 2.4 mm in the design model space. Following this, the simulation analysis was carried out. Further, a homogenization algorithm was used for homogenizing the stress distribution, increasing porosity, and controlling peak stress of the porous structure by adjusting the strut diameters. The results showed that compared with the initial porous structure, the position of the large stress regions remained unchanged, and the peak stress fluctuated slightly in the mandible and fixation system with the optimized porous structure under two occlusions. The optimized porous structure had a higher porosity and more uniform stress distribution, and the maximum stress was lower than the target stress value. The design and optimization technique of the porous structure presented in this paper can be used to control peak stress, improve porosity, and fabricate a lightweight scaffold, which provides a potential solution for mandibular reconstruction.

Semi-automated digital workflow to design and evaluate patient-specific mandibular reconstruction implants

The reconstruction of large mandibular defects with optimal aesthetic and functional outcomes remains a major challenge for maxillofacial surgeons. The aim of this study was to design patient-specific mandibular reconstruction implants through a semi-automated digital workflow and to assess the effects of topology optimization on the biomechanical performance of the designed implants. By using the proposed workflow, a fully porous implant (LA-implant) and a topology-optimized implant (TO-implant) both made of Ti-6Al-4V ELI were designed and additively manufactured using selective laser melting. The mechanical performance of the implants was predicted by performing finite element analysis (FEA) and was experimentally assessed by conducting quasi-static and cyclic biomechanical tests. Digital image correlation (DIC) was used to validate the FE model by comparing the principal strains predicted by the FEM model with the measured distribution of the same type of strain. The numerical predictions were in good agreement with the DIC measurements and the predicted locations of specimen failure matched the actual ones. No statistically significant differences (p < 0.05) in the mean stiffness, mean ultimate load, or mean ultimate displacement were detected between the LA- and TO-implant groups. No implant failures were observed during quasi-static or cyclic testing under masticatory loads that were substantially higher (>1000 N) than the average maximum biting force of healthy individuals. Given its relatively lower weight (16.5%), higher porosity (17.4%), and much shorter design time (633.3%), the LA-implant is preferred for clinical application. This study clearly demonstrates the capability of the proposed workflow to develop patient-specific implants with high precision and superior mechanical performance, which will greatly facilitate cost- and time-effective pre-surgical planning and is expected to improve the surgical outcome.

Clinically relevant preclinical animal models for testing novel cranio-maxillofacial bone 3D-printed biomaterials

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.

Segmental mandibular reconstruction in patients with poor lower extremity perfusion, vessel-depleted necks and/or profound medical frailty

PURPOSE OF REVIEW

Options for segmental mandibular reconstruction in patients poorly suited to undergo fibula free flap (FFF).

RECENT FINDINGS

Although FFF is the current 'gold standard' for segmental mandibular reconstruction, other reconstructive options must be considered when FFF is contraindicated or disfavoured and/or patient frailty precludes a lengthy anaesthetic. In addition to various nonvascularized and soft tissue only reconstructions, excellent osseous free flap alternatives for functional segmental mandibular reconstruction may be employed. The subscapular system free flaps (SSSFF) may be ideal in frail and/or elderly patients, as SSSFF allows for early mobility and does not alter gait. In extensive and/or symphyseal defects, functional mandibular reconstruction in lieu of a free flap is extremely limited. Pedicled segmental mandibular reconstructions remain reasonable options, but limited contemporary literature highlights unpredictable bone graft perfusion and poor long-term functional outcomes.

SUMMARY

There are several excellent free flap alternatives to FFF in segmental mandibular reconstruction, assuming adequate cervical recipient vessels are present. On the basis of the current literature, the optimal mandibular reconstruction for the medically frail, elderly and/or patients with extreme vessel-depleted necks is limited and debatable. In qualifying (i.e. limited, lateral) defects, soft tissue only reconstructions should be strongly considered when osseous free flaps are unavailable.

Optimal placement of fixation system for scaffold-based mandibular reconstruction

A current challenge in bone tissue engineering is to create favourable biomechanical conditions conducive to tissue regeneration for a scaffold implanted in a segmental defect. This is particularly the case immediately following surgical implantation when a firm mechanical union between the scaffold and host bone is yet to be established via osseointegration. For mandibular reconstruction of a large segmental defect, the position of the fixation system is shown here to have a profound effect on the mechanical stimulus (for tissue regeneration within the scaffold), structural strength, and structural stiffness of the tissue scaffold-host bone construct under physiological load. This research combines computer tomography (CT)-based finite element (FE) modelling with multiobjective optimisation to determine the optimal height and angle to place a titanium fixation plate on a reconstructed mandible so as to enhance tissue ingrowth, structural strength and structural stiffness of the scaffold-host bone construct. To this end, the respective design criteria for fixation plate placement are to: (i) maximise the volume of the tissue scaffold experiencing levels of mechanical stimulus sufficient to initiate bone apposition, (ii) minimise peak stress in the scaffold so that it remains intact with a diminished risk of failure and, (iii) minimise scaffold ridge displacement so that the reconstructed jawbone resists deformation under physiological load. First, a CT-based FE model of a reconstructed human mandible implanted with a bioceramic tissue scaffold is developed to visualise and quantify changes in the biomechanical responses as the fixation plate's height and/or angle are varied. The volume of the scaffold experiencing appositional mechanical stimulus is observed to increase with the height of the fixation plate. Also, as the principal load-transfer mechanism to the scaffold is via the fixation system, there is a significant ingress of appositional stimulus from the buccal side towards the centre of the scaffold, notably in the region bounded by the screws. Next, surrogate modelling is implemented to generate bivariate cubic polynomial functions of the three biomechanical responses with respect to the two design variables (height and angle). Finally, as the three design objectives are found to be competing, bi- and tri-objective particle swarm optimisation algorithms are invoked to determine the most optimal Pareto solution, which represents the best possible trade-off between the competing design objectives. It is recommended that consideration be given to placing the fixation system along the upper boundary of the mandible with a small clockwise rotation about its posterior end. The methodology developed here forms a useful decision aid for optimal surgical planning.

[Anatomy of the deep circumflex iliac artery perforators and reconstruction of complex mandibular defects with chimeric deep circumflex iliac artery perforator flap]

OBJECTIVE

To investigate the anatomy of the perforator vessels of the deep circumflex iliac artery (DCIA) and the techniques for repairing mandibular complex defect using chimeric deep circumflex iliac artery perforator flap (DCIAPF).

OBJECTIVE

We analyzed the origin, distribution, number and courses of the perforator vessels of the DCIA, and measured the outside diameters of the vessels at the origin in 6 adult cadaveric specimens (12 sides) with latex perfusion. From July, 2018 to September, 2019, based on the results of anatomical study and imaging findings and using the digital surgical guide plate, we harvested DCIAPF from 4 patients for repairing mandibular body or angle defects and oral soft tissue defects.

OBJECTIVE

The perforating vessels of the DCIA included abdominal muscular branches, osteomusculocutaneous branches and terminal musculocutaneous branches. The abdominal muscle branches originated from the DCIA inguinal segment in 4 and from both the inguinal and iliac segments in 2 of the specimens. The osteomusculocutaneous branches all originated from the internal iliac crest in 75% and from both the inguinal and internal iliac crest segments in 25% of cases; the inguinal segment gave rise to only one perforating branch. The number of the musculocutaneous perforating branches was 1 (58.3%) or 2 (41.7%). In the 4 patients undergoing mandibular reconstruction, the DCIAPF survived in all cases with good recovery of the donor site wound. Satisfactory facial appearance with good oral morphology and occlusal relationship was achieved at 1 month postoperatively in all the patients. None of the patients experienced obvious functional abnormalities at the donor site, and imaging examination confirmed successful reconstruction of the oromandibular defects in all the cases.

OBJECTIVE

A good understanding of the anatomic characteristics of the perforator vessels of the DCIA combined with imaging examinations and digital surgery technology facilitates the harvest of DCIAPF for repairing mandibular body or angle defects complicated by oral soft tissue defects.

The application of chimeric deep circumflex iliac artery perforator flap for oromandibular reconstruction: A case report

RATIONALE

The free fibular flap is considered the gold standard, particularly for a mandibular defect combined with a significant soft tissue defect. However, the fibular flap has the disadvantages of a lack of height for postoperative dental restoration and donor site skin graft if the skin paddle is wider than 5 cm. The larger bone and soft tissue defects tend to be reconstructed using either a scapula or a combination of iliac artery and radial free flap. Few cases involving reconstruction using chimeric deep circumflex iliac artery perforator flap (DCIAPF) for mandibular defect combined with more significant soft tissue defects have been reported due to perforator variations. We successfully performed oromandibular reconstruction using chimeric DCIAPF.

PATIENT CONCERNS

A 56-year-old male patient was admitted due to "constant pain in the gradually enlarged right lower gingival mass since the previous four months." The patient had no other obvious symptoms, and no history of diabetes or hypertension was reported. The patient reported long-term smoking and drinking habits.

DIAGNOSES

Computed tomography (CT) revealed a neoplasm in the right buccal space, which is primarily considered a malignancy. The pathological results of a gingival mass biopsy presented squamous cell carcinoma.

INTERVENTIONS

No operative contraindications were confirmed after regular tests and examinations were undertaken. The patient underwent a primary extent resection of a 6-cm-long mandible, including mass and suprascapulohyoid neck dissection. The oromandibular defects were then reconstructed with chimeric DCIAPF, simultaneously using the iliac crest bone flap to repair the mandibular lateral segment defect and the skin paddle to repair the intraoral soft tissue defect of 5 × 10 cm.

OUTCOMES

The total operating time was five and half hours and blood loss was approximately 500 ml. The operation was successful, with no infections or flap loss. Six months postoperatively, CT showed that the iliac crest bone had connected to the alveolar bone of the mandible. The height of the iliac crest bone was sufficient for postoperative dental restoration. The patient healed without obvious complications and no tumor recurrence.

LESSONS

Chimeric DCIAPF is an excellent option for mandibular angle or body segment defects combined with significant soft tissue defects.

Appearance-Related Distress and Social Functioning after Head and Neck Microvascular Reconstruction

OBJECTIVES/HYPOTHESIS

To better understand aesthetic patient-reported outcomes and psychosocial quality of life (QOL) after head and neck microvascular reconstruction for benign or malignant tumors.

STUDY DESIGN

Single-center prospectively obtained in-office validated questionnaire-based study.

METHODS

Analysis of prospectively collected surveys at a tertiary care academic center from June 2018 to February 2021. Patients completed two FACE-Q scales: Appearance-Related Psychosocial Distress (ARPD) and Social Function (SF). Survey scores, demographics, operative course, and adjuvant therapy data underwent univariate and multivariable analyses.

RESULTS

One hundred and three patients completed surveys at a median of 13.5 months postoperatively (interquartile range: 5.2-30.8). Mean ARPD from 0 (no distress) to 100 (maximum distress) was 32.4 (standard error of the mean [SEM]: 2.7). Mean SF from 0 (worst functioning) to 100 (best functioning) was 55.5 (SEM: 2.7). Postoperative adjuvant radiation was associated with 13.9% higher ARPD (95% CI: 3.4-24.4, P = .019) and 10.4% lower SF (95% CI: -20.7 to -0.1, P = .047). Each appearance-related question on the ARPD scale independently predicted impaired SF (P < .001 for all questions). Upon multivariable logistic regression, osteocutaneous reconstruction, compared to soft tissue alone (P = .043), and postoperative adjuvant radiation (P = .014) were associated with higher levels of ARPD. Age, sex, relationship status, anxiety or depression history, defect location, and hospital stay were not significantly associated with ARPD or SF scores.

CONCLUSIONS

Aesthetic outcomes are important determinants of psychosocial QOL following head and neck microvascular reconstruction: an effect that is worsened by adjuvant radiation. Reconstructive surgeons should prioritize aesthetic outcomes, in addition to functional restoration, to optimize social functioning in patients with head and neck tumors.

LEVEL OF EVIDENCE

3 Laryngoscope, 131:E2204-E2211, 2021.

Medication-related osteonecrosis and osteoradionecrosis of the jaws: Update and current management

Medication related osteonecrosis of the jaws (MRONJ) and osteoradionecrosis of the jaws (ORNJ) are two different diseases of quite similar appearance. MRONJ is mainly due to antiresorptive or antiangiogenic drug therapy and ORNJ to radiotherapy. The present work aimed at presenting and comparing the current knowledge on MRONJ and ORNJ. They both present as an exposure of necrotic bone and differ in some clinical or radiological characteristics, clinical course and mostly in treatment. They share similar risk factors. A tooth extraction is more frequently found as a triggering factor in MRONJ. The frequency of a maxillary localisation seems higher for MRONJ. On computed tomographic images, a periosteal reaction seems characteristic of MRONJ. More frequent pathological fractures seem to occur in ORNJ. It is mandatory, for ORNJ diagnosis, to exclude a residual or recurrent tumour using histological examination. Both MRONJ and ORNJ are challenging to treat and cannot be managed similarly. For both, it would still be worth to optimise awareness within the medical community, patients' oral hygiene and dental cares to improve their prevention and make their incidences decrease. Conservative therapy is more frequently achieved for MRONJ than ORNJ and surgical resection is more often performed for ORNJ. For both diseases, the last treatment possible in refractory cases is a surgical extensive resection with free flap reconstruction. A MRONJ classification is widely used today, whereas no consensus exists to date for ORNJ classification. We propose a classification that could play this role.

Safety of boneless reconstruction of the mandible with a CAD/CAM designed titanium device: The replica cohort study

OBJECTIVE

We evaluated the safety of REPLICA, a CAD/CAM-designed patient-specific titanium mandible, in patients with mandibular defects not suitable for reconstruction with traditional techniques.

PATIENTS AND METHODS

We performed a cohort study with a composite primary outcome assigned at the end of a 1-year follow-up. The outcome was assigned in the presence of all the following: 1) absence of intraoral or skin extrusion of REPLICA; 2) decrease or cessation of oral pain; 3) stability or increase in mouth opening; 4) resumption of oral feeding without the need of nasogastric tube; 5) absence of fracture at multidetector computer tomography (MDCT); 6) absence of displacement (MDCT); 7) absence of screw loosening (MDCT). The secondary outcome was the patient-reported QOL at 6 months of follow-up as detected by the EORTC QLQ-C30 and QLQ-H&N35 questionnaires.

RESULTS

Between March 2012 and June 2017, 18 consecutive patients, with a median (IQR) age of 67 (65;74) underwent reconstruction of mandibular defects with REPLICA at our Unit. The primary outcome was reached by 14 of the 18 patients. QOL data were available for 15 patients at the 6-month follow-up, showing a good profile of general and disease-specific QOL.

CONCLUSION

REPLICA offered a safe solution at 1-year for the treatment of mandibular defects not suitable for reconstruction with traditional techniques, and was associated with subjective well-being and satisfaction. Further studies are needed to assess the full range of indications of REPLICA.

Reconstruction of segmental mandibular defects: Current procedures and perspectives

Background

The reconstruction of segmental mandibular defects remains a challenge for the reconstructive surgeon, from both a functional and an esthetic point of view.

Methods

This clinical review examines the different techniques currently in use for mandibular reconstruction as related to a range of etiologies, including the different bone donor sites, the alternatives to free flaps (FFs), as well as the contribution of computer‐assisted surgery. Recent progress and the perspectives in bone tissue engineering (BTE) are also discussed.

Results

Osseous FF allows reliable and satisfying outcomes. However, locoregional flap, distraction osteogenesis, or even induced membrane techniques are other potential options in less favorable cases. Obtaining an engineered bone with satisfactory mechanical properties and sufficient vascular supply requires further investigations.

Conclusions

Osseous FF procedure remains the gold standard for segmental mandible reconstruction. BTE strategies offer promising alternatives.