Scope of magnesium ceria nanocomposites for mandibular reconstruction: Degradation and biomechanical evaluation using a 3-dimensional finite element analysis approach

Magnesium/Ceria nanocomposites (Mg/xCeO2 NCs (x = 0.5 %, 1 % and 1.5 %)) prepared by using powder metallurgy and microwave sintering method are assessed for their corrosion rate for a period of 28 days. As per the immersion tests results, the addition of ceria nanoparticles to pure Mg, brought about a noteworthy improvement to corrosion resistance. A corrosion rate of approximately 0.84 mm/year for Mg/0.5CeO2 and 0.99 mm/year for Mg/1.0CeO2 nanocomposites were observed. Another aspect of the study involves employing the simulation method i.e. finite element analysis (FEA) to compare the stress distribution in magnesium-ceria nanocomposite based screws and circular bars especially for Mg/0.5CeO2 and Mg/1.0CeO2. Further, the simulation also gives a perception of the impact of masticatory forces, the biting force and shear stress exerted on the Mg/0.5CeO2 and Mg/1.0CeO2 based screws. The simulations results show that the screws showed an acceptable level of stresses for a biting force up to 300 N. The circular bar as well kept its stresses at acceptable levels for the same load of 300N. The shear stress results indicated that a biting force up to 602 N can be safely absorbed by Mg/0.5CeO2 screw. The comprehensive approach allows for a better understanding of the corrosion behavior, stress distribution, and mechanical properties of the Mg/CeO2 nanocomposites, enabling the development of effective temporary implants for craniofacial trauma fixation that can withstand normal physiological forces during mastication. The study reported in this paper aims to target Mg/xCeO2 NCs for temporary implants for craniofacial trauma fixation.

A comparison of accuracy among different approaches of static-guided implant placement in patients treated with mandibular reconstruction: A retrospective study

OBJECTIVE

This study aimed to evaluate the differences in the accuracy of immediate intraoral, immediate extraoral, and delayed dental implant placement with surgical guides (static computer-aided implant surgery) in patients treated with mandibular reconstruction.

METHODS

This was a retrospective study. The patients were divided into three groups: immediate intraoral placement (IIO), immediate extraoral placement (IEO), and delayed placement (DEL). Four variables were used to compare the planned and actual implant positions: angular deviation, three-dimensional (3D) deviation at the entry point of the implant, 3D deviation at the apical point of the implant, and depth deviation.

RESULTS

The angular deviation was significantly higher in the IIO group than in the IEO (p < .05) and DEL (p < .05) groups. The 3D deviation at the entry point was significantly higher in the IIO group than in the IEO (p < .05) and DEL (p < .01) groups. The 3D deviation at the apical point was significantly higher in the IIO group than in the IEO (p < .01) and DEL (p < .01) groups. The depth deviation was significantly higher in the IIO group than in the IEO (p < .05) and DEL (p < .05) groups. There was no statistical difference between the IEO and DEL group in angular and 3D deviation.

CONCLUSION

With surgical guides, among the different approaches for implant placement, delayed implant placement remains the most accurate approach for patients treated with mandibular reconstruction.

Pedicled osteomyocutaneous pectoralis major flap with osseous rib harvest for salvage mandibular reconstruction: Case and technique

In the era of free flap reconstruction, mandibular defects are routinely reconstructed with osseous free flaps, and non-free flap bony reconstruction options are limited. A patient with T4N0 mandibular squamous cell carcinoma underwent resection with fibula free flap reconstruction of a parasymphyseal to angle defect. After free flap failure due to venous congestion, the flap was explanted. He declined additional free flap reconstruction and elected to proceed with pedicled osteomyocutaneous pectoralis major with rib. In this case presentation, we discuss the technical details of harvest of this flap using the 6th rib. The pedicled osteomyocutaneous pectoralis major flap with osseous rib harvest, which is infrequently described in the literature, remains a viable option for bony reconstruction, particularly in the salvage setting.

Deep Circumflex Iliac Artery Flap Reconstruction in Brown Class I Defect of the Mandible Using a Three-Component Surgical Template System

BACKGROUND

Computer-assisted surgery is widely used in mandibular reconstruction, but the process is not well described for cases using the deep circumflex iliac artery flap (DCIA) as the donor site. This study aimed to present a DCIA-based three-component surgical template system (3-STS) in patients with a mandibular Brown class I defect.

METHODS

This retrospective cohort study compared clinical outcomes of mandibular reconstruction with DCIA flap using 3-STS or conventional surgical templates. The primary outcome of the study was the accuracy of reconstruction, and the secondary outcomes included surgical time and bone flap ischemia time. Surgery-related parameters and functional outcomes were also recorded and compared.

RESULTS

Forty-four patients (23 in the 3-STS group and 21 in the control group) between 2015 and 2021 were included. Compared with the control group, the 3-STS group had higher accuracy of reconstruction, indicated by lower deviation in absolute distance (1.45 ± 0.76 mm versus 2.02 ± 0.89 mm; P = 0.034), and less deviation in coronal and sagittal angles (0.86 ± 0.53 degree versus 1.27 ± 0.59 degrees, P = 0.039; and 2.52 ± 1.00 degrees versus 3.25 ± 1.25 versus, P = 0.047) between preoperative and postoperative computed tomographic imaging. Surgical time and bone flap ischemia time were significantly reduced in the 3-STS group compared with the control group (median time, 385 minutes versus 445 minutes and 32 minutes versus 53 minutes, respectively; P < 0.001). In addition, masseter attachment was preserved in the 3-STS group but not in the control group. No differences were found in adverse events or other clinical variables.

CONCLUSION

The 3-STS can improve accuracy, simplify intraoperative procedures to increase surgical efficiency, and preserve functionality in mandibular reconstruction for Brown class I defects.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, III.

Immediate Inferior Alveolar Nerve Reconstruction With Ablative Mandibular Resection Results in Functional Sensory Recovery

BACKGROUND

Ablative mandibular resection with sacrifice of the inferior alveolar nerve (IAN) results in loss of sensation and decreased quality of life.

PURPOSE

The purpose of this study is to evaluate functional sensory recovery (FSR) of immediate IAN allograft reconstruction performed during ablative mandibular resection at 1 year following surgery.

STUDY DESIGN, SETTING, SAMPLE

This is a single-center retrospective cohort study that included consecutive subjects who underwent mandibular resection with IAN discontinuity and used a nerve allograft of ≥40 mm.

PREDICTOR/EXPOSURE/INDEPENDENT VARIABLE

The primary predictor variable is the use of an immediate nerve allograft in mandibular reconstruction.

MAIN OUTCOME VARIABLE(S)

The main outcome variable is FSR at 1 year using the Medical Research Council Scale.

COVARIATES

Covariates include subject age, sex, specific pathology, nerve gap length, and development of neuropathic pain.

ANALYSES

Statistical analysis of comparison of neurosensory outcomes was measured by bivariate statistics, weighted values, repeated measures, analysis of variance, and McNemar test.

RESULTS

The study sample was composed of 164 subjects, of whom 55 (33.5%) underwent nerve allograft reconstruction and 30 (18.3%) did not have nerve reconstruction. Seventy-nine subjects (48.2%) did not meet the inclusion criteria. In the entire nerve allograft group of 55 subjects, FSR was achieved in 80% at 1 year; however, in benign disease alone, 31 of 33 (94%) achieved FSR at 1 year. In the nonallograft group (all benign disease), only 2 of 30 (7%) achieved FSR at 1 year. The significant covariates were age and pathology. Benign pathologic resections were 5.2 times more likely to achieve FSR than malignancies, and all subjects ≤ 18 years of age achieved FSR. After adjusting for age, sex, pathology, nerve gap length, nerve allograft was significantly associated with achieving FSR at 1 year (adjusted odds ratio = 5.52, 95% confidence interval = (1.03, 29.51), P value = .045 < .05).

CONCLUSION AND RELEVANCE

Immediate long-span IAN allograft reconstruction is effective in restoration of sensation with an overall 80% of subjects achieving FSR at 1 year, while benign disease resulted in 94% FSR at 1 year. Immediate IAN reconstruction should be considered with mandibular resection involving the IAN, especially for children and benign disease.

[Two Cases of Advanced Lower Gingival Carcinoma Treated Surgically Using a Novel Patient-Specific Full Custom- Made Mandibular Reconstruction Plate System]

The treatment of advanced lower gingival carcinoma requires postoperative chemoradiotherapy; therefore, simultaneous hard-tissue reconstruction may not be indicated. In these cases, mandibular reconstruction is performed using a temporal reconstruction plate and various skin flaps. Herein, we reported 2 cases of advanced lower gingival carcinoma treated with a novel computer-assisted patient-specific, fully custom-made mandibular reconstruction plate system(Cosmofix®)in combination with a pedicle/free flap. In case 1, an 80-year-old female patient was diagnosed with right lower gingival carcinoma( cT4aN3bM0, Stage ⅣB). Under general anesthesia, she underwent tracheostomy, bilateral neck dissection, segmental mandibulectomy, and mandibular reconstruction using Cosmofix® in combination with an ulnar forearm free flap. In case 2, an 81-year-old male patient was diagnosed with right lower gingival carcinoma(cT4aN2bM0, Stage ⅣA). The patient underwent maintenance dialysis and required minimally invasive surgery using a pedicle flap. Under general anesthesia, the patient underwent tracheostomy, right modified radical neck dissection, segmental mandibulectomy, and mandibular reconstruction using Cosmofix® in combination with a pectoralis major myocutaneous flap. Postoperative facial morphology, occlusion, eating, swallowing, articulation, and other dysfunctions were minimal in both the cases. Adjuvant chemoradiotherapy was recommended. In conclusion, the utilization of the Cosmofix® system enabled both esthetic and functional reconstruction following segmental mandibulectomy for advanced lower gingival carcinoma.

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.

Automated calculation of ontology-based planning proposals: An application in reconstructive oral and maxillofacial surgery

BACKGROUND

Structured modelling of surgical knowledge and its automated processing is still challenging. The aim of this work is to introduce a novel approach for automated calculation of ontology-based planning proposals in mandibular reconstruction and conduct a feasibility study.

METHODS

The presented approach is composed of an RDF(S) ontology, a 3D mandible template and a calculator-optimiser algorithm to automatically calculate reconstruction proposals with fibula grafts. To validate the viability of the approach, a feasibility study was conducted on 164 simulated mandibular reconstructions.

RESULTS

The ontology defines 244 different reconstruction variants and 80 analyses for optimization. In 146 simulated cases, a proposal could be automatically calculated (average time 8.79 ± 4.03 s). The assessments of the proposals by three clinical experts indicate the viability of the approach.

CONCLUSIONS

Due to the modular separation between computational logic and domain knowledge, the developed concepts can be easily maintained, reused and adapted for other applications.

Customed 3D-printed Polyetheretherketone (PEEK) Implant for Secondary Salvage Reconstruction of Mandibular Defects: Case Report and Literature Review

Given the insufficient height of single-barrel fibula and inadequate bone volume of double-barrel vascularized fibula in mandibular reconstruction, it is a better choice to combine the upper full-thickness vascularized fibula with the lower half-thickness nonvascularized fibula. However, the nonvascularized fibula may fail due to complications, affecting the facial shape and occlusal function. Polyetheretherketone is a thermoplastic polymer used for bone defect reconstruction due to its good mechanical properties and biocompatibility. This case report mainly presents a secondary salvage reconstruction of the mandible by using customed 3-dimensional-printing polyetheretherketone, which restored the continuity and symmetry of the mandible, improved the patient's facial shape, and restored functional occlusion through dental implants. After a 28-month follow-up, no complications occurred, and the patient was satisfied with the final restoration.

Impact of fibula osteoseptocutaneous flap laterality in mandibular and intraoral reconstruction

BACKGROUND

The fibula flap has been the workhorse flap for mandibular reconstruction. However, relationships among the bone, skin, and vessels raise concerns about donor-side selection. This study aimed to clarify its impact on clinical outcomes.

METHODS

Between September 2013 and June 2021, 61 cases of fibula osteoseptocutaneous flaps for mandibular and intraoral reconstruction were categorized into the landing-down (N = 25) and swing-up (N = 36) groups depending on whether the skin was easily accessible within the oral cavity. The demographics, operative findings, and outcomes of the cases were compared.

RESULTS

Overall, seven (11%) flaps developed skin necrosis, including four partial and three total necrosis. The skin necrosis rate was higher in the swing-up than in the landing-down group (19% vs. 0%, p = 0.035).

CONCLUSIONS

When using the fibula osteoseptocutaneous flap for mandibular and intraoral reconstructions, ensuring that the skin is properly located within the oral cavity could reduce the risk of skin necrosis.

A novel simulation module for segmental mandibulectomy and mandible reconstruction using 3D models

INTRODUCTION

Mandibular resection and reconstruction are common but complex procedures in head and neck surgery. Resection with adequate margins is critical to the success of the procedure but technical training is restricted to real case experience. Here we describe our experience in the development and evaluation of a mandibular resection and reconstruction simulation module.

METHODS

3D printed (3DP) models of a mandible with a pathologic lesion were developed from imaging data from a patient with an ameloblastoma. During an educational conference, otolaryngology trainees participated in a simulation in which they reviewed a CT scan of the pathologic mandible and then planned their osteotomies before and after handling a 3DP model demonstrating the lesion. The adequacy of the osteotomy margins was assessed and components of the simulation were rated by participants with pre- and post-training surveys.

RESULTS

52 participants met criteria. After reviewing the CT scan, 34 participants (65.3 %) proposed osteotomies clear of the lesion. This proportion improved to 48 (92.3 %, p = 0.001) after handling the 3D model. Among those with initially adequate margins (n = 33), 45.5 % decreased their margins closer to the ideal, 27.2 % made no revision, 21.2 % widened their margins. 92 % of participants found the simulation beneficial for surgical planning and technical training. After the exercise, the majority of participants had increased confidence in conceptualizing the boundaries of the lesion (69.2 %) and their abilities to ablate (76.5 %).

CONCLUSIONS

The structured mandibulectomy simulation using 3DP models was useful in the development of trainee experience in segmental mandible resection.

LAY SUMMARY

This study presents the first mandibulectomy simulation module for trainees with the use of 3DP models. The use of a 3DP model was also shown to improve the quality of surgical training.

Evolution of Medical Modeling and 3D Printing in Microvascular Midface Reconstruction: Literature Review and Experience at MD Anderson Cancer Center

Reconstruction of the midface represents a challenge for reconstructive microsurgeons given the formidable task of restoring both aesthetics and functionality. In particular, preservation of proper globe positioning and maintaining normal vision are as important as restoring the proper projection of the midface and enabling a patient to speak and eat as normally as possible. The introduction of virtual surgical planning (VSP) and medical modeling has revolutionized bony reconstruction of the craniofacial skeleton; however, the overwhelming majority of studies have focused on mandibular reconstruction. Here, we introduce some novel advances in utilizing VSP for bony reconstruction of the midface. The present review aims (1) to provide a review of the literature on the use of VSP in midface reconstruction and (2) to provide some insights from the authors' early experience.

Patient-specific 3D-printed mini-versus reconstruction plates for free flap fixation at the mandible: Retrospective study of clinical outcomes and complication rates

This study aimed to compare the clinical outcomes and complication rates of patient-specific 3D-printed mini- and reconstruction plates for free flap fixation in mandibular reconstruction. A retrospective monocentric study was carried out between April 2017 and December 2021 to analyze patients undergoing immediate mandibular reconstruction using fibula free flaps and osteosynthesis using patient-specific 3D-printed implants. Eighty-three patients with a mean age of 63.6 years were included. The mean follow-up period was 18.5 months. Patient-specific 3D-printed plates were designed as reconstruction plates (38 patients), miniplates (21 patients) or a combination of reconstruction- and miniplates (24 patients). With miniplates, plate removal was performed significantly more often via an intraoral approach (p < 0.001) and in an outpatient setting (p = 0.002). Univariate analysis showed a higher fistula rate with reconstruction plates (p = 0.037). Multivariate analysis showed no significant differences in complications. Case-control matching demonstrated significantly lower rates of fistula (p = 0.017) and non-union (p = 0.029) in the combined group. This retrospective study shows a tendency towards reduced complication rates with patient-specific 3D-printed miniplates in comparison to patient-specific 3D-printed reconstruction plates for immediate mandibular reconstruction with fibula free flaps.

Factors Affecting Complete Oral Rehabilitation in Patients With Vascularized Free Fibula Flap Mandibular Reconstruction: A 10-Year Retrospective Study

The fibula is the preferred bone flap for mandibular reconstructions due to its many advantages, including the possibility to insert dental implants. All patients who received a mandibular reconstruction with a vascularized free fibula flap at the Uppsala University Hospital between 2009 and 2019 were retrospectively examined regarding the proportion of implant insertion and factors that affected implant outcome. Forty-one patients had 42 fibula flap reconstructions. Eleven patients (27%) received dental implants and 8 (20%) completed dental rehabilitation. Patient death and cancer recurrence were the main reasons for not receiving implants. The survival rates of implants placed in irradiated and nonirradiated fibulas were 15% and 76%, respectively. Less than 20% of reconstructed patients received an implant-supported prosthesis. Implants placed in an irradiated fibula should be considered at high risk for implant loss.

Comparing donor site morbidity in osteocutaneous radial forearm versus fibula free flap for mandibular reconstruction

PURPOSE

The osteocutaneous radial forearm free flap has gained popularity as a less morbid option for oromandibular reconstruction compared to the fibular free flap. However, there is a paucity of data regarding direct outcome comparison between these techniques.

METHODS

Retrospective chart review of 94 patients who underwent maxillomandibular reconstruction intervened from July 2012-October 2020 at the University of Arkansas for Medical Sciences. All other bony free flaps were excluded. Endpoints retrieved encompassed demographics, surgical outcomes, perioperative data, and donor site morbidity. Continuous data points were analyzed using independent sample t-Tests. Qualitative data was analyzed using Chi-Square tests to determine significance. Ordinal variables were tested using the Mann-Whitney U test.

RESULTS

The cohort was equally male and female, with a mean age of 62.6 years. There were 21 and 73 patients in the osteocutaneous radial forearm free flap and fibular free flap cohorts, respectively. Excluding age, the groups were otherwise comparable, including tobacco use, and ASA classification. Bony defect (OC-RFFF = 7.9 cm, FFF = 9.4 cm, p = 0.021) and skin paddle (OC-RFFF = 54.6 cm2, FFF = 72.21 cm2, p = 0.045) size were larger in the fibular free flap group. However, no significant difference was found between cohorts with respect to skin graft. There was no statistically significant difference between cohorts regarding the rate of donor site infection, tourniquet time, ischemia time, total operative time, blood transfusion, or length of hospital stay.

CONCLUSIONS

No significant difference in perioperative donor site morbidity was found between patients undergoing fibular forearm free flap and osteocutaneous radial forearm flap for maxillomandibular reconstruction. Osteocutaneous radial forearm flap performance was associated with significantly older age, which may represent a selection bias.

Fibula Jaw-during-Admission

BACKGROUND

Fibula Jaw-in-a-Day (JIAD) is considered the most advanced approach for segmental mandibular defect reconstruction and dental rehabilitation. However, it has limitations and challenges for further pursuit. We propose Fibula Jaw-during-Admission (JDA) as a solution.

MATERIALS AND METHODS

From 2019 to 2021, six patients received fibula "Jaw-during-Admission." Segmental mandibulectomy, fibula transfer, and immediate dental implantation were performed simultaneously during a single surgery. Intraoral scans were used to fabricate temporary light occlusion contact dental prostheses while on the ward prior to discharge during the first and second week post operation. The prostheses were installed before discharge and changed to permanent ones with normal occlusal contact in the clinic at about six months after X-ray confirmation of bone healing.

RESULTS

All six surgeries succeeded. Four patients received palatal muco-periosteal graft after debridement of peri-implant overgrown granulation tissue. Follow-up ranged from 12 to 34 months (average 21.2 months) and revealed good function and appearance in all patients.

CONCLUSION

Fibula JDA is superior to the Fibula JIAD approach for simultaneous mandibular reconstruction with fibula and dental rehabilitation. There is no need for postoperative intermaxillary fixation. The surgery can be performed more reliably with less stress. It provides an additional opportunity for dental rehabilitation if initial dental prosthesis installation during JIAD fails. Postreconstruction intraoral scans provide greater precision and more flexibility in milling dental prosthesis which are mapped to the reconstructed mandible during the postoperative period.

Craniomaxillofacial Trauma: The Past, Present and the Future

Reconstruction of facial trauma has seen a significant evolutionary leap in the last 100 years. The current surgical management of facial fractures was made possible by the efforts and creativity of pioneer surgeons, advances in anatomic understanding, and the continued development of biomaterials and imaging technologies. Virtual surgical planning (VSP) and 3-dimensional printing (3DP) are being incorporated into the management of acute facial trauma. The integration of this technology at the point of care is rapidly expanding globally. This article reviews the history of the management of craniomaxillofacial trauma, current practices, and future directions. The use of VSP and 3DP in facial trauma care is highlighted with a description of EPPOCRATIS, a rapid point-of-care process incorporating VSP and 3DP at the trauma center.

A novel alloplastic grid reconstruction plate for the mandible - Retrospective comparative clinical analysis of failure rates and specific complications

PURPOSE

This study aimed to investigate the effect of three different osteosynthesis plate systems on failure rates and complications after continuity-interrupting mandibular resections with alloplastic reconstructions.

MATERIALS AND METHODS

Records of respective patients from 2010 to 2020 were analyzed retrospectively. The analyses included the osteosynthesis plate type (2.4 MANDIBULAR (RP1: MANDIBULAR [Medicon®, Tuttlingen, Germany]; RP2: Modus® Reco 2.5 [Medartis®, Basel, Switzerland]; and RP3: Modus 2 Mandible [Medartis®, Basel, Switzerland]), extent & location of the defect, age, sex, radiotherapy, and nicotine abuse. In case of failure, timepoint, and the problem, namely oral/extraoral dehiscence, screw loosening, and plate fractures that led to removal, were analyzed. Complications were classified according to Clavien-Dindo system.

RESULTS

A total of 136 patients were included. The mean follow-up time was 18 ± 26 months. Survival rates after 1, 2, and 5 years were 69.9%, 66.9%, and 64.7%, respectively. Although survival was not significantly associated with the reconstruction system, the most frequent complications were seen in cases of RP1 & RP2 when compared to RP3 (p = 0.033). In brief, dehiscences were seen significantly less often in cases of RP3 (12.5%) when compared to RP1 (44.7%) and RP2 (26.9%; p = 0.024). Fractures of the osteosynthesis systems occurred in 3 of 4 cases (75%) with RP1, in 1 of 4 cases (25%) using RP2, and in no single case using the RP3 system (p = 0.03). Most of the observed complications occurred up to 12 months postoperatively. A total plate survival rate of 64.7% and a total plate complication rate of 47.8% were seen.

CONCLUSION

In conclusion, it seems that RP3 should be preferred over RP1 and RP2 regarding failure rates and complications.

Outcomes of immediate dental implants in vascularised bone flaps for mandibular reconstruction

BACKGROUND

The aim of this study is to assess the outcomes of immediate implant placement for dental rehabilitation following mandibular reconstruction with vascularised bone flaps in a single Australian tertiary cancer centre.

METHODS

A retrospective analysis of patients who underwent immediate dental implant or delayed placement in vascularised bone flaps was performed. Primary outcome measures assessed included the number of implants placed, operative time, complication rates, time to radiotherapy initiation, dental rehabilitation rates and time to dental rehabilitation.

RESULTS

In total, 187 dental implants were placed in 52 patients, of which 34 patients underwent immediate implant placement and 18 had delayed implant placement. There were no significant differences in the postoperative complication rate (32% immediate vs. 33% delayed, P = 0.89) or time to postoperative radiotherapy (median 42 days immediate vs. 47 days delayed, P = 0.24). Dental rehabilitation was achieved in 62% of the immediate cohort versus 78% of the delayed cohort. The time to be fitted with a dental prosthesis was significantly shorter in the immediate cohort (median 150 days immediate vs. 843 days delayed, P = 0.002).

CONCLUSIONS

The placement of immediate dental implants at the time of primary reconstruction of the mandible is a safe procedure and facilitates timely dental rehabilitation.

Pediatric Mandibular Reconstruction With Free Serratus Anterior-Rib Composite Flap: A Case Report

ABSTRACT

Reconstruction of children's mandibles after mandibular resection for benign or malignant tumors is challenging. Microvascular flap reconstruction is a common treatment option for restoring mandibular continuity after the resection of oral cavity neoplasms.We presented 2 cases of childhood mandibular reconstruction after tumor wide excision and segmental mandibulectomy, one for malignant cancer and one for benign ossifying fibroma, with serratus-rib composite free flap. All 2 patients had a favorable facial profile, functional outcome, and dental occlusion at the last follow-up. The development of children's mandible and donor site needs to be considered compared with adult's mandibular reconstruction. Given its reliability and utility, this flap can be an alternative for pediatric mandibular reconstruction compared with the free fibular flap and other candidates.

Dental implant treatment in vascularized bone flaps after jaw reconstruction

Jaw defects caused by various reasons often seriously affect appearance and function. The goal of the treatment of oral and maxillofacial tumors should include the cure of the tumor and the restoration of premorbid function. The development of microsurgery and digital surgery technology has promoted the development of jaw reconstruction with vascularized free bone flap. Good appearance and improved predictability could be obtained with the help of preope-rative visual design. How to rehabilitate occlusal function on the reconstructed jaw and improve the quality of life of patients has become an important research direction. This article discusses the challenge of jaw reconstruction, the selection of vascularized bone flap, the choice of implant timing, the treatment of peri-implant soft tissue, and the influence of radiotherapy on implants after jaw reconstruction.

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.

[Evaluation of the effect of simultaneous neuralized iliac bone flap on the preservation of lower lip and chin sensation during mandibular reconstruction]

PURPOSE

To evaluate the effect of reconstructing inferior alveolar nerve and preserving the sensation of lower lip and chin in repairing mandibular defect by simultaneous neuralized iliac bone flap.

METHODS

Patients with continuous mandibular defects requiring reconstruction were randomly assigned to the innervated(IN) group and the control(CO) group by random number table. In the IN group, the deep circumflex iliac artery and recipient vessels were anastomosed microscopically during mandible reconstruction, and the ilioinguinal nerve(IN), mental nerve(MN) and inferior alveolar nerve(IAN) were anastomosed at the same time. In the CO group, only vascular anastomosis was performed without nerve reconstruction. During the operation, the nerve electrical activity after nerve anastomosis was detected by nerve monitor, and the sensory recovery of lower lip was recorded by two-point discrimination(TPD), current perception threshold (CPT) and Touch test sensory evaluator(TTSE) test. SPSS 26.0 software package was used for data analysis.

RESULTS

According to the inclusion and exclusion criteria, a total of 20 patients were included, with 10 patients in each group. All the flaps survived in both groups, and no serious complications such as flap crisis occurred, and no obvious complications occurred in the donor site. The results of TPD test, CPT test and TTSE test all indicated that the degree of postoperative hypoesthesia in the IN group was less(P＜0.05).

CONCLUSIONS

Simultaneous nerve anastomosis vascularized iliac bone flap can effectively preserve the feeling of lower lip and improve the postoperative quality of life of patients. It is a safe and effective technique.

Biomechanical validation of structural optimized patient-specific mandibular reconstruction plate orienting additive manufacturing

BACKGROUND AND OBJECTIVE

Owing to the unexpected in vivo fracture failure of the original design, structural optimized patient-specific mandibular reconstruction plates (PSMRPs) were created to boost the biomechanical performance of bridging segmental bony defect in the mandibular reconstruction after tumor resection. This work aimed to validate the biomechanical benefit of the structural optimized PSMRPs relative to the original design and compare the biomechanical performance between PSMRP1 with generic contour customization and PSMRP2 with a tangent arc upper margin in mandibular angle region.

METHODS

Finite Element Analysis (FEA) was used to evaluate the biomechanical behavior of mandibular reconstruction assemblies (MRAs) concerning these two structural optimized PSMRPs by simulating momentary left group clenching and incisal clenching tasks. Bonded contact was set between mandibular bone and fixation screws and between PSMRP and fixation screws in the MRA, while the frictionless connection was allocated between mandibular bone and PSMRP. The loads were applied on four principal muscles, including masseter, temporalis, lateral and medial pterygoid, whose magnitudes along the three orthogonal directions. The mandibular condyles were retrained in all three directions, and either the left molars or incisors area were restrained from moving vertically.

RESULTS

The peak von Mises stresses of structural optimized PSMRPs (264 MPa, 296 MPa) were way lower than that of the initial PSMRP design (393 MPa), with 33 and 25% reduction during left group clenching. The peak magnitude of von Mises stress, minimum principal stress, and maximum principal strain of PSMRP1 (264 MPa, 254 MPa; -297 MPa, -285 MPa; 0.0020, 0.0020) was lower than that of PSMRP2 (296 MPa, 286 MPa; -319 MPa, -306 MPa; 0.0022, 0.0020), while the peak maximum principal stress of PSMRP1 (275 MPa, 257 MPa) was higher than that of PSMRP2 (254 MPa, 235 MPa) during both left group clenching and incisal clenching tasks.

CONCLUSIONS

The structural optimized PSMRPs reveal their biomechanical advantage compared with the original design. The PSMRP1 presents better biomechanical performance to the patient-specific mandibular reconstruction than PSMRP2 as a result of its superior safety, preferable flexibility, and comparable stability. The PSMRP2 provides biomechanical benefit in reducing the maximum tension than PSMRP1, indicated by lower peak maximum principal stress, through tangent arc upper margin in mandibular angle region.

Computer-Assisted Mandibular Reconstruction with a Single-Step Free Fibula Flap and Simultaneous Implant Placement

The free fibula flap is a reliable approach used to reconstruct maxillofacial osseous defects. Virtual surgical planning facilitates the execution of such segmental bony reconstruction, usually preceding the placement of endosseous implants for dental rehabilitation. Novel advances in digital technology allow for fabrication of 3D guides for implant placement in the fibula bone segments before their fixation to the facial defect, with reduced ischemic time, reduced treatment time, faster dental rehabilitations, and unprecedented improvements in the overall treatment efficiency. This case report illustrates the use of digitally designed 3D-printed surgical plates for a single-stage surgery of free fibula flap with implant placement. The patient was successfully treated and followed over 2 years. Comparison between preoperative virtual planning and postoperative scans revealed a high accuracy of implant and bone segment positioning.

Quality of life after segmental mandibulectomy and free flap for mandibular osteonecrosis: Systematic review

OBJECTIVE

Review QOL outcomes among patients undergoing segmental mandibulectomy and bony free flap reconstruction for ONJ.

DATA SOURCES

PubMed was searched for MeSH terms "Quality of life," "Osteonecrosis," "Osteoradionecrosis," "Bisphosphonate-associated osteonecrosis of the jaw," "Free tissue flaps," and "Mandibular reconstruction."

REVIEW METHODS

English language studies with QOL outcomes data for patients undergoing free flap reconstruction for advanced ONJ were included. 197 records were initially screened; 18 full texts assessed; 10 full texts included. PRISMA guidelines were followed.

RESULTS

Ten studies were included in this systematic review: six retrospective, three retrospective with comparison groups, and one prospective. In studies with comparison groups, ONJ patients have worse self-reported QOL than the general population as well as head and neck cancer patients without ONJ. Nearly all patients with QOL measurements (220/235 patients) had ONJ from prior radiation. Segmental mandibulectomy and bony free flap improved overall QOL in over half of patients, as well as pain associated with ONJ in 70-75 % of patients. Surgery did not improve long-term effects of radiation such as chewing, swallowing, and salivary production. Donor site morbidity rarely affects QOL.

CONCLUSIONS

Osteonecrosis of the jaw (ONJ) worsens quality-of-life, and advanced disease often requires segmental mandibulectomy and bony free flap reconstruction. Patients and surgeons may expect improvement in some, but not all, domains of patient-reported QOL by the use of segmental mandibulectomy and reconstruction for advanced ONJ.

Accuracy of Mandibular Reconstruction with a Vascularised Iliac Flap Using 3D Templates: a Systematic Review

OBJECTIVE

To conduct a systemic review for guidance regarding the application of templates in mandibular reconstruction with vascularised iliac flaps.

METHODS

By searching PubMed, EMBASE and the Cochrane Library and collecting relevant literature, information about the types and accuracy of templates was extracted. Data relating to surgical time were also included for further analysis.

RESULTS

Eight studies were included. The data analysis showed that the accuracy of operations with templates was higher than that of conventional surgery. The mean deviation was between 0.70 and 3.72 mm. The operational time was shortened to 314.4 minutes and the graft ischemic time was reduced to 15.6 to 26.8 minutes. Application of functional or specifically designed templates can improve the accuracy and shorten surgical time.

CONCLUSION

Templates can increase the accuracy and efficiency of mandibular reconstruction with vascularised iliac flaps, which will benefit patients' prognosis and subsequent functional restoration. Further studies should be conducted into application of templates to improve the accuracy of reconstructions.

Rates of bone reabsorption and union in mandibular reconstruction using the osteocutaneous radial forearm free flap

BACKGROUND

Historical concerns over bone resorption and malunion of the osteocutaneous radial forearm free flap (OCRFFF) limited its widespread adoption for head and neck reconstruction, despite lack of outcomes data evaluating this notion.

METHODS

A retrospective cohort study was performed including patients 18 years or older who underwent reconstruction of the mandible using an OCRFFF. Linear modeling and logistic regression were used to evaluate the change in bone volume and union over time.

RESULTS

One hundred and twenty-one patients were included in the study. A mixed effects linear model incorporating age, sex, treatment type, and number of bone segments did not demonstrate a significant loss of bone volume over time. A logistic regression model identified lack of adjuvant treatment and time to be significantly associated with complete union.

CONCLUSION

This study supports that the OCRFFF is a stable form of osseus reconstruction for defects of the head and neck.

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.

[Mandibular defect reconstruction using digital design-assisted free fibula flap and threedimensional finite element analysis of stress distribution]

OBJECTIVE

To evaluate of the clinical value of preoperative digital design-assisted free fibular flap for reconstruction of different types of mandibular tissue defects using three-dimensional finite element analysis.

METHODS

This retrospective analysis was conducted in 48 patients undergoing reconstruction of mandibular defects following tumor resection using free fibular flaps. In 24 of the cases, digital design of free fibular flap was performed before the operation (experimental group), and the other 24 patients with digital design of the flap served as the control group. At 1 year after the surgery, the patients underwent mandibular CT examination and a 3-dimensional finite element model of the mandible was constructed using Mimics, Geomagic, Solidworks and Ansys. The stress distribution on the reconstructed mandibles with the H, L, or LCL types of defects, classified according to the HCL classification method, was determined under specific constraints and load conditions and compared between the experimental and control groups.

RESULTS

The operations were completed successfully in all the patients, and none of them had tumor recurrence at 1 year after the operation. On the reconstructed mandibles using free fibular flaps, the stress was concentrated mainly on the neck of the bilateral condyle, the anterior and posterior edges of the ascending mandibular ramus, and the connection between the posterior end of the fibula and the mandible. A large size of mandibular defects caused greater stress at the contralateral condyle. For L-shaped defects, the maximum stress at the healthy and ipsilateral condyle necks and transplanted fibula were significantly lower, while the stress level at the healthy side mandibular angle was significantly greater in the experimental group than in the control group (P < 0.05). For LCL type defects, the maximum stress at the contralateral condyle neck was smaller but the stress in the condyle area on the affected side, the bilateral mandibular angle area and the fibula area were all significantly greater in the experimental group than in the control group (P < 0.05).

CONCLUSION

Digital design of the free fibular flap improves the accuracy of reconstruction of mandibular defects and helps to achieve uniform stress distribution on the reconstructed mandible.

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

BACKGROUND

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.

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.

Near-total mandibular reconstruction following osteoradionecrosis with double scapula tip free flap: A case report

Near-total mandibular reconstruction poses many challenges to reconstructive surgeons. The purpose of this article is to present a challenging case in a patient with osteoradionecrosis of the mandible requiring a near-total mandibular reconstruction using bilateral scapula tip free tissue reconstruction. A 68-year-old African-American male with a history of T2N0M0 squamous cell carcinoma of the tonsil presented with advanced stage osteoradionecrosis of the mandible. Reconstruction was planned using 3D Systems (Denver, CO), mandibular osteotomies were planned inferior to the sigmoid notch on the ascending rami. Neither fibula flap was amenable for harvesting due to poor vasculature of the patient's lower extremities, and bilateral scapula tip free flaps were subsequently planned. The post-operative course was complicated by venous congestion in the right scapula flap which required revision to the venous anastomosis on POD 1. The patient had intraoral breakdown that required debridement in the operating room and application of a cellular matrix. The patient fully recovered from the acute surgery and was discharged home without a tracheostomy. At the last follow up visit, the patient was taking 100% of diet peroral and had no signs of oral incompetence, mental projection was satisfactory, and the ability to verbally communicate was unimpaired. We report a complex case of near-total mandibular reconstruction using simultaneous bilateral scapula tip free flaps. While we do not advocate simultaneous bilateral scapula tip free flaps as the standard of care for large mandibulectomy defects, it may be considered for patients in which traditional osseous free flaps are not available.

[Application of 3D printing technology under three-dimensional reconstruction in mandibular reconstruction]

PURPOSE

To explore the application value of 3D printing technology under three-dimensional reconstruction in mandibular reconstruction.

METHODS

Eighty-four patients with mandibular defect reconstruction were divided into two groups by different operation methods: 3D group(n=42) and control group(n=42). Patients in the control group underwent routine operation, while patients in the experimental(3D) group underwent three-dimensional reconstruction with 3D printing technology. The operation conditions, incidence of complications, recovery of facial features and occlusal relationship were recorded. SPSS 23.0 software package was used for statistical analysis of the data.

RESULTS

The operation time of 3D group was significantly shorter than that of the control group, and the amount of bleeding was significantly less than that of the control group(P<0.05). The recovery rate of facial appearance and occlusal relationship in 3D group was significantly higher than in the control group(95.24% vs 78.57%, P<0.05). Compared with the control group, the movement distance of mandibular points in 3D group was significantly smaller before and after operation(P<0.05). The satisfaction scores of chewing function and pronunciation recovery in the two groups were close(P>0.05), but compared with the control group, the satisfaction scores of appearance recovery in the 3D group were significantly higher(P<0.05).

CONCLUSIONS

3D reconstruction under 3D printing technology can reduce intraoperative bleeding, shorten the operation duration, and achieve good shape recovery with high degree of satisfaction.

Knowledge Acquisition and Construction of a RDF-Ontology for Computer-Assisted Surgery

The integration of surgical knowledge into virtual planning systems plays a key role in computer-assisted surgery. The knowledge is often implicitly contained in the implemented algorithms. However, a strict separation would be desirable for reasons of maintainability, reusability and readability. Along with the Department of Oral and Maxillofacial Surgery at Heidelberg University Hospital, we are working on the development of a virtual planning system for mandibular reconstruction. In this work we describe a process for the structured acquisition and representation of surgical knowledge for mandibular reconstruction. Based on the acquired knowledge, an RDF(S) ontology was created. The ontology is connected to the virtual planning system via a SPARQL interface. The described process of knowledge acquisition can be transferred to other surgical use cases. Furthermore, the developed ontology is characterised by a reusable and easily expandable data model.

Simultaneous Reconstruction of Mandibular and Maxillary Defects Using the Single Free Fibular Osseocutaneous Flap: Case Series and Review of the Literature

BACKGROUND

The facial profile requires adequate maxillary and mandibular projection. Although oral cancer tumor ablation might create ipsilateral maxillary and mandibular defect, fibular flap is popular in mandibular defect reconstruction. However, the maxillary defect results in sunken cheek or oral contracture. A single fibular flap can provide several struts to rebuild 2 jaws with adequate 3-dimensional spatial placement.

MATERIALS AND METHODS

In total, 7 cases of secondary oral contracture and 2 cases of primary oncologic tumor ablation underwent single fibular flap for 2 jaws. Using multiple osteotomies, the distal fibular struts were used for the upper jaw, the second struts were discarded (3-4 cm), and proximal struts were used for mandible defect reconstruction. There were 5 accompanying free flaps for facial lining (2) and contralateral oral contracture release (3).

RESULTS

All flaps survived without distal strut avascular necrosis, but 2 patients died from tumor metastasis. These patients presented adequate middle and lower facial profile. One patient underwent mandibular fibula strut distraction osteogenesis followed by integrated teeth on both jaws.

CONCLUSIONS

Single fibular transfer can accomplish 2 jaw bony defects and facial profile reconstruction. It can release oral contracture functionally and correct sunken cheek aesthetically. The reconstructed fibula can allow secondary teeth implantation rehabilitation.

Biomechanical and Mechanostat analysis of a titanium layered porous implant for mandibular reconstruction: The effect of the topology optimization design

A porous scaffold/implant is considered a potential method to repair bone defects, but its mechanical stability and biomechanics during the repair process are not yet clear. A mandibular titanium implant was proposed and designed with layered porous structures similar to that of the bone tissue, both in structure and mechanical properties. Topology was used to optimize the design of the porous implant and fixed structure. The finite element analysis was combined with bone "Mechanostat" theory to evaluate the stress and osteogenic property of the layered porous implant with 3 different fixation layouts (Model I with 4 screws, Model II with 5 screws and Model III with 6 screws) for mandibular reconstruction. The results showed that Model III could effectively reduce the stress shielding effect, stress within the optimized implant, defective mandible, and screws were respectively dropped 48.18%, 44.23%, and 57.27% compared to Model I, and the porous implant had a significant stress transmission effect and maintained the same stress distribution as the intact mandible after the mandibular defect was repaired. The porous implant also showed a significant mechanical stimulation effect on the growth and healing of the bone tissue according to the bone "Mechanostat" theory. The combination of porous structure with the topology technique is a promising option to improve the mechanical stability and osteogenesis of the implant, and could provide a new solution for mandibular reconstruction.

Association between non-vascularised bone graft failure and compartment of the defect in mandibular reconstruction: a systematic review and meta-analysis

Controversy exists regarding the influence of the graft placement site in the mandible on the success of non-vascularised bone grafts. In this study, we examine the association between the compartment of the mandibular defect and the bone graft failure rate. A systematic literature review and meta-analysis was performed using MEDLINE, Embase, and Cochrane databases. Failure rates according to the compartment of mandibular defect were extracted and analysed by meta-analysis. The Newcastle-Ottawa Scale was used to assess the quality of the studies, and publication bias was evaluated using funnel plots. The search strategy identified 27 publications. After screening, five were selected for review. Based on the result of comparison among these five, we found no significant statistical association between the bone graft failure rate and compartment of mandibular defect, although further investigation of prospective randomised cohort studies is required.