Method For Mandibular Reconstruction Research Articles

Investigation of the Mechanical Strength of Artificial Metallic Mandibles with Lattice Structure for Mandibular Reconstruction.

Mandibular reconstructive surgery is necessary for large bone defects. Although various reconstruction methods have been performed clinically, there is no mandibular reconstruction method that meets both sufficient strength criteria and the patient's specific morphology. In this study, the material strength of the cylindrical lattice structures formed by electron-beam melting additive manufacturing using titanium alloy powder was investigated for mandibular reconstruction. The virtual strengths of 28 lattice structures were compared using numerical material tests with finite element method software. Subsequently, to compare the material properties of the selected structures from the preliminary tests, compression test, static bending test and fatigue test were conducted. The results showed that there were correlations with relative density and significant differences among the various structures when comparing internal stress with deformation, although there was a possibility of localized stress concentration and non-uniform stress distribution based on the lattice structure characteristics. These results suggest that the lattice structure of body diagonals with nodes and a cell size of 3.0 mm is a potential candidate for metallic artificial mandibles in mandibular reconstruction surgery.

The comparison between various methods of mandibular reconstruction based on finite element analysis.

The Mandible can be damaged by pathological factors, tumors, trauma, infection, and needs a surgical operation for reconstruction and restoring function. There are different methods for the reconstruction of mandible. Based on the surgical approach, primary reconstruction of mandible by reconstruction plate after resection is necessary for maintaining mandibular symmetric and esthetic of the lower third of the face. A finite element model of mandible and masticatory muscles was produced from a normal person (male with 35-year-old). The normal model was resected from the left sixth tooth to the second tooth. The pathological model was reconstructed in different conditions by macro plate. Different conditions were analyzed and compared based on bite force on right fifth tooth, stress developed on screws and macro plate. The finite element analysis results showed that maximum bite force and lower stress on screws were seen in the pathological model (condition 5) when one macro plate and six screws were inserted in the mid-body. The findings showed that the use of two macro plates causes lower stress on it than when we use one. Use of one macro plate and six screws is the best choice in mandibular immobilization which decrease the stress applied on bone and increase the bite force. Because of less stress developed on macro plates and screws, use of two macro plates or one macro plate in mid-body area are also preferred.

Genetic determinants of periosteum-mediated craniofacial bone regeneration: a systematic review.

Periosteum-mediated bone regeneration (PMBR) is a recognized method for mandibular reconstruction. Despite its unpredictable nature and the limited degree to which it is understood, it does not share the concerns of developmental changes to donor and recipient tissues that other treatment options do. The definitive role of the periosteum in bone regeneration in any mammal remains largely unexplored. The purpose of this study was to identify the genetic determinants of PMBR in mammals through a systematic review. Our search methodology was designed in accordance with the PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) guidelines. We conducted a quality assessment of each publication, and evaluated the differences in gene expression between days 7 and 15. A total of four studies satisfied the inclusion criteria. The subjects and tissues examined in these studies were Wistar rat calvaria in two studies, mini-pigs in one study, and calves and mice in one study. Three out of the four studies achieved the necessary quality score of ≥ 3. Gene expression analysis showed increased activity of genes responsible for angiogenesis, cytokine activities, and immune-inflammatory responses on day 7. Additionally, genes related to skeletal development and signaling pathways were upregulated on day 15. Conclusions: The results suggest that skeletal morphogenesis is regulated by genes associated with skeletal development, and the gene expression patterns of PMBR may be characterized by specific pathways.

Adipose-Derived Stem Cells Enhance Graft Incorporation and Mineralization in a Murine Model of Irradiated Mandibular Nonvascularized Bone Grafting.

Nonvascularized bone grafting represents a practical method of mandibular reconstruction. However, the destructive effects of radiotherapy on native bone preclude the use of nonvascularized bone grafts in head and neck cancer patients. Adipose-derived stem cells have been shown to enhance bone healing and regeneration in numerous experimental models. The purpose of this study was to determine the impact of adipose-derived stem cells on nonvascularized bone graft incorporation in a murine model of irradiated mandibular reconstruction. Thirty isogenic rats were randomly divided into 3 groups: nonvascularized bone graft (control), radiation with nonvascularized bone graft (XRT), and radiation with nonvascularized bone graft and adipose-derived stem cells (ASC). Excluding the control group, all rats received a human-equivalent dose of radiation. All groups underwent mandibular reconstruction of a critical-sized defect with a nonvascularized bone graft from the contralateral hemimandible. After a 60-day recovery period, graft incorporation and bone mineralization were compared between groups. Compared with the control group, the XRT group demonstrated significantly decreased graft incorporation (P = 0.011), bone mineral density (P = 0.005), and bone volume fraction (P = 0.001). Compared with the XRT group, the ASC group achieved a significantly increased graft incorporation (P = 0.006), bone mineral density (P = 0.005), and bone volume fraction (P = 0.013). No significant differences were identified between the control and ASC groups. Adipose-derived stem cells enhance nonvascularized bone graft incorporation in the setting of human-equivalent radiation.

Use of a Fibula Free Flap for Mandibular Reconstruction in Severe Craniofacial Microsomia in Children with Obstructive Sleep Apnea.

This is a retrospective study describing a multi-stage protocol for the management of severe mandibular hypoplasia in craniofacial microsomia (CFM) with accompanying obstructive sleep apnea (OSA). Patients with severe mandibular hypoplasia require reconstruction functionality and esthetical features. In the cohort, reconstructions based on free fibular flaps (FFF) may be the most effective way. Patients aged 4-17 years with severe mandibular hypoplasia were treated with FFF, which initially improved the respiratory function assessed on polysomnography (AHI). In the next stages of treatment of cases with respiratory deterioration, it was indicated to perform distraction osteogenesis (DO) of the mandible and the structures reconstructed with FFF. All surgeries were planned in accordance with virtual surgery planning VSP. The aim of the study was to prospectively assess the effectiveness of multi-stage mandibular reconstruction in craniofacial microsomia with the use of a free fibula flap in terms of improving respiratory failure due to obstructive sleep apnea (OSA). The FFF reconstruction method, performed with virtual surgical planning (VSP), is proving to be an effective alternative to traditional methods of mandibular reconstruction in patients with severe CFM with OSA.

Risk factors assessment in fibular free flap mandibular reconstruction

The fibular free flap (FFF) is the best choice method for mandibular reconstruction. However, the failure and the complications risk factors (RF) are not yet fully identified. This study aims to analyze these RF in order to improve the success rate. This retrospective study includes all patients who benefited from a FFF mandibular reconstruction between the first of January, 2014 and the thirty-first of December, 2018 in the Department of Stomatology and Maxillofacial Surgery department of the CHU Saint-Pierre Hospital, Brussels, Belgium. Thirty patients benefited from this intervention. The overall success rate was 90%. Majority of the patients were men (67%) (mean age: 52 years). The main associated co-morbidities were: alcohol (50%), tobacco consumption (67%) and previous radiotherapy (20%). The mean operative time was 9,5hours. The morbidities rates at the receiving site (RS) and the donor site (DS) were respectively 43% and 30%. Infection and dehiscence of the RS were the main complications. Statistical analysis identified RF for RS infections: atherosclerosis and operative time; RS dehiscence (previous cervical dissection and secondary reconstruction); flap necrosis (ischemia time, rate of infection at the recipient site, history of radiation therapy, alcohol consumption, National Nosocomial Infection Surveillance score (NNISS), and history of cervical dissection); and DS morbidities (NNISS and dehiscence rate at the DS in the early period). The FFF mandibular reconstruction offers a significant success rate. Nevertheless, this study highlighted several failure and complications RF of the procedure. Previous neck dissection and radiotherapy, operative and the ischemia time, were RF associated with complication at the RS. Furthermore, the NNIS score and the dehiscence rate were also reported as RF for FFF necrosis.

"Endotracheal Tube" as a Temporary Method of Mandibular Reconstruction in Infant with Juvenile Ossifying Fibroma.

"Endotracheal Tube" as a Temporary Method of Mandibular Reconstruction in Infant with Juvenile Ossifying Fibroma.

Determining the optimal osteotomy distance with the fibula free flap in mandibular reconstruction.

Fibula free tissue transfer is a common and reliable method for mandibular reconstruction. Functional outcomes from this procedure are dependent on the successful union of the osseous segments postoperatively. This study was conducted to define the maximum gap-size criteria for osseous union to occur at osteotomy sites in fibula free flap reconstruction of the mandible. Retrospective chart review. Tertiary care academic center. A retrospective chart review of computed tomography and medical records was conducted on patients who underwent fibula free flap surgery and had imaging of the mandible at <3months and >6months after surgery. Distances between osteotomies were measured and evaluated for interval healing. Secondary data included subject age, sex, smoking status, diabetes, number of osteotomies, complications, and adjuvant therapy. Thirty-eight osteotomy sites were analyzed from thirteen subjects and a total of 190 measurements were made. The mean gap size at the first scan that demonstrated union by the second scan interval was 1.31mm and mean gap size demonstrating non-union was 2.55mm (p<0.01). Complication rate, number of osetotomies, adjuvant therapy, or medical co-morbidities did not significantly affect rates of union. In this study, osseous union was achieved with a mean osteotomy gap size of 1.31mm. The data suggests that distances between ossesous segments >2.55mm have a higher risk of non-union. We believe the information from this study will help augment current and future techniques in the field of mandible reconstruction.

Osseointegration of Dental Implants Placed in Free Fibula Graft

Objective: The aim of this article is to review survival/success rate of dental implants inserted invascularized free fibula grafts. Background: Placement of dental implants following mandibular reconstruction during ablative surgery using vascularized free fibula grafts has proved to be a successful technique to achieve good mastication and complete dental rehabilitation. Insertionof implantsinto the new mandible provides a better access to the bone, interdental relationships are easier to assess, and oral rehabilitation can be acquired in a short span of time. Result: Study design, treatment methods, follow-ups, defect location, and morphology varied among studies. A definite conclusion could not be reached. Future studies with long-term follow-ups are required. Conclusion: Osseointegration of dental implants is a relatively safe technique with minimal complications. Patient selection plays a vital role, dental implants may be placed primarily, thus reducing the time to oral rehabilitation. Vascularized fibula grafts are a suitable method of mandibular reconstruction and are amenable to be successful in both primary and secondary endosseous implantation.

Functional and Aesthetic Osseous Free Flap Mandible Reconstruction Using a Low-cost Method: Long-term Results.

Background:Mandibular segment loss due to tumoral resection or infectious sequelae causes functional alterations with disorders in mastication, swallowing, speech, and aesthetic alterations with facial asymmetry due to deformity secondary to soft tissue collapse. Reconstructive treatment should recover function and aesthetics. This paper presents a low-cost method of mandibular reconstruction in a series of 6 patients with different years of follow-up (average follow-up time of 11.6 years) using the fibula and scapula free flaps.Methods:Five female patients and 1 male patient received mandibular reconstruction using osseous free flaps, 5 with the fibula and 1 with the scapula osseous free flap. The patient’s ages at the time of surgery ranged from 8 to 62 years (mean 33.1 years). Stainless steel wire was used as the osteosynthesis material, with intermaxillary fixation for 40 days postoperatively and masticatory rehabilitation using mucodental-supported prostheses.Results:To evaluate the aesthetic result and the facial symmetry, a questionnaire and the photographs of all the cases were sent to 8 plastic surgeons. The functional result was evaluated in 5 of the 6 patients using the Spanish version of the Oral Health Impact Profile. All flaps survived, dental occlusion was achieved in all patients, no tumors recurred, masticatory function was normal without swallowing or speech alterations, and the transplanted bone hypertrophied and spontaneously remodeled, providing facial symmetry with good aesthetic results.Conclusion:We present a low-cost and universally applicable mandibular reconstruction method, with long-term follow-up and good aesthetic and functional results.

Nonvascularized Iliac Bone Reconstruction for the Mandible Without Maxillofacial Skin Scarring

There are many methods to reconstruct the mandible, but they are often accompanied by trauma, which can lead to scarring of the maxillofacial skin. The purpose of this study was to show the utility of a minimally invasive method for reconstruction of the mandible with nonvascularized iliac bone grafts without a skin scar, as well as to evaluate the success rate and complications. This was a retrospective case series. We retrospectively analyzed patients who underwent transoral resection of benign mandibular pathologies, followed by nonvascularized iliac bone graft reconstruction. The primary outcome variable was the success rate of the bone grafts. Secondary outcome variables were postoperative complications at the grafted bone recipient and donor sites, the long-term absorptivity of grafted bone, and the type of mandibular defect. We computed descriptive statistics or performed the χ2 test for each variable. Overall, 54 patients were included in the study, including 21 male and 33 female patients, with an age range of 10 to 65years. The complete survival rate was 87.0% (47 of 54 patients), and the partial survival rate was 98.1% (53 of 54).The average bone absorption rate 3years after surgery was 1.8 to 30.7%. We propose a new classification method for mandibular defects based on the extent of the tumor, location of the osteotomy, and degree of surgical difficulty. Intraoral nonvascularized iliac bone grafting is a highly successful minimally invasive method for mandibular reconstruction. It is also one of the best methods for mandibular reconstruction in patients with benign mandibular tumors without soft tissue involvement.

CAD/CAM composite mandibular reconstruction method using a fibular free flap: a reconstruction planning approach using computed tomographic angiography scan for fibular and perforator vessels pre-operative evaluation

CAD/CAM composite mandibular reconstruction method using a fibular free flap: a reconstruction planning approach using computed tomographic angiography scan for fibular and perforator vessels pre-operative evaluation

Nonvascularized Bone Graft Reconstruction of the Irradiated Murine Mandible: An Analogue of Clinical Head and Neck Cancer Treatment.

Nonvascularized bone grafts (NBGs) represent a practical method of mandibular reconstruction that is precluded in head and neck cancer patients by the destructive effects of radiotherapy. Advances in tissue-engineering may restore NBGs as a viable surgical technique, but expeditious translation demands a small-animal model that approximates clinical practice. This study establishes a murine model of irradiated mandibular reconstruction using a segmental iliac crest NBG for the investigation of imperative bone healing strategies. Twenty-seven male isogenic Lewis rats were divided into 2 groups; control bone graft and irradiated bone graft (XBG). Additional Lewis rats served as graft donors. The XBG group was administered a fractionated dose of 35Gy. All rats underwent reconstruction of a segmental, critical-sized defect of the left hemi-mandible with a 5 mm NBG from the iliac crest, secured by a custom radiolucent plate. Following a 60-day recovery period, hemi-mandibles were evaluated for bony union, bone mineralization, and biomechanical strength (P < 0.05). Bony union rates were significantly reduced in the XBG group (42%) compared with controls (80%). Mandibles in the XBG group further demonstrated substantial radiation injury through significant reductions in all metrics of bone mineralization and biomechanical strength. These observations are consistent with the clinical sequelae of radiotherapy that limit NBGs to nonirradiated patients. This investigation provides a clinically relevant, quantitative model in which innovations in tissue engineering may be evaluated in the setting of radiotherapy to ultimately provide the advantages of NBGs to head and neck cancer patients and reconstructive surgeons.

3D Reconstruction of Mandibular Defects using CAD/CAM Designed Zirconia Prosthesis

Background: Reconstruction of mandibular defects with autogenous free bone graft is considered the preferred method. However, the optimum reconstruction technique of mandibular defects is still controversial. Objectives: To assess the efficacy and safety of the zirconia individual designed CAD/CAM prosthesis for the mandibular reconstruction. Materials and methods: We used a new method (zirconia prosthesis) for the reconstruction of mandibular defects due to various causes. The study was carried out in the Oral and Maxillofacial Department of Al-Ramadi Teaching Hospital during a period of 62 months from January 2012 to March 2017. Data were collected for each patient regarding the age, gender, site and cause of the defect, investigations, operative technique, complications, outcome, and the duration of the follow-up. Results: Twenty patients, 14 were men and 6 women; the patients’ ages ranged from 19 to 70 years. The majority of the defects were caused by tumors, while, 40% due to congenital or traumatic causes. The success rate of the prosthesis taking was 95%. And in these cases, esthetic and functional outcomes were restored or improved after the reconstruction in all subjects. Conclusion: We described a novel method for mandibular reconstruction with zirconium individual-designed CAD/CAM model. We advise to use this method owing to the high success rate, the less major rate of complications in comparison with other methods, and high rate of functional and esthetic outcome.

Computer-Aided Design and Three-Dimensional-Printed Surgical Templates for Second-Stage Mandibular Reconstruction.

It is extremely difficult in clinical practice to accurately reset the physiologic positions of the mandibular condyle and ramus because of ongoing bone remodeling, muscle stretching, occlusal disorders, and other factors; this makes it difficult to obtain a good shape for a reconstructed mandible, as well as a good condylar position. The present study aimed to investigate a standardized method for mandibular reconstruction in cases of obsolete mandibular defects, using a 3-dimensional (3D)-printed surgical template enhanced by computer-aided design. We collected computed tomography data preoperatively to computerize the physiologic positions of the mandibular condyle and ramus on the sagittal, axial, and coronal planes. Surgical simulation and 3D-printed template preparation were then conducted to assist in the implementation of actual surgery. Postoperative review was performed to assess the repositioning of the condyle, where patients were found to regain a satisfactory condyle position. Reconstruction error was ±0.56 mm, fulfilling the preoperative design. No complications and discomfort were reported. Overall, the combined use of computer-aided design and 3D-printed surgical templates can standardize mandibular reconstruction in cases of obsolete mandibular body defects.

Evaluation of accuracy and sensory outcomes of mandibular reconstruction using computer-assisted surgical simulation

PurposeTo introduce a modified protocol for mandibular reconstruction and evaluate the protocol using a standardized assessment method. MethodThis retrospective study involved a case series of nine patients who underwent mandibular reconstruction between 2015 and 2017. The modular protocol comprised three novel modifications in terms of computer-assisted surgical simulation (CASS); surgical template (ST), and surgical procedure. The standardized postoperative evaluation consisted of operation time, part comparison analysis (PCA), facial symmetry, and mechanical quantitative sensory testing. ResultsThe surgery successfully removed the affected mandible and preserved the inferior alveolar neurovascular bundle (IANB). PCA revealed that the mean error and standard deviation were 0.92 and 0.96 mm, respectively, for all mandibular surface sites. Follow-up results showed good facial symmetry, existence of sensation in lower lip, and no significant differences in pulp vitality between both sides (p = 0.181). Also, the results showed a reduction in the overall operating time. ConclusionThe modified mandibular reconstruction method used in this study could repair lateral mandibular defects and preserve the sensory function of the chin and lower lip.

Mandibular reconstruction in elderly patients.

The choice of reconstructive technique for a segmental mandibular defect in elderly patients is controversial. The aim of this study was to establish an algorithm for selecting a method of mandibular reconstruction in elderly patients. We retrospectively evaluated 121 patients aged ≥65 years who underwent immediate microvascular mandibular reconstruction after oncologic resection. Patients were divided into three groups based on method of reconstruction: vascularized bone graft (n = 49), mandibular reconstruction plate and soft tissue flap (n = 22), and soft-tissue flap (n = 50). We compared perioperative outcomes among groups and investigated factors affecting the choice of reconstructive technique. Rates of postoperative complications did not differ significantly among groups. Mandibular reconstruction plate was indicated only for anterior mandibular defects. Soft-tissue flap was indicated for posterior mandibular defects in patients aged ≥75 years or with a poor postoperative Eichner index. Mandibular reconstruction plate and soft-tissue flap can be good alternatives to vascularized bone graft in the elderly. Our algorithm uses defect type, patient age, and postoperative Eichner index to determine reconstructive technique.

Accuracy of CAD/CAM mandibular reconstruction: A three-dimensional, fully virtual outcome evaluation method

PurposeComputer-aided design/computer-aided manufacturing (CAD/CAM) methods for mandibular reconstruction have improved both functional and morphological results. We evaluated the accuracy of the CAD/CAM method for mandibular reconstruction and assessed the quantitative and qualitative reproducibility of virtual preoperative planning. Materials and methodsA total of 34 consecutive patients treated with mandibular reconstruction using the CAD/CAM method between January 2011 and October 2017 were included in this study. The accuracy of the reconstruction was assessed using the automated Hausdorff distance function of the simulation software, which set the postoperative mesh as the target. This made it possible to calculate the minimum error, the maximum error, and the mean error for each reconstruction in exactly the same way and with the same settings as the difference between the postoperative mesh and virtual planning. Finally, the coloured quality mapper function was applied to superimposition of the STL files, allowing us to visually render the obtained data on differences between preoperative planning and surgical outcome. ResultsThe average mean error obtained after performing an accuracy evaluation of our reconstructions was 1 mm (range 0.4–2.46 mm). Based on the colour map areas, the maximum error was located in the symphysis area. The body and ramus areas showed the greatest accuracy in terms of planning reproducibility. ConclusionThis is the first study to assess the three-dimensional reproducibility of virtual planning using the CAD/CAM method for mandibular reconstruction, in a homogeneous sample of 34 cases. Our data suggest that CAD/CAM microvascular reconstruction can result in a very high degree of reproducibility. This occurs in complex areas as well as the condylar region and in the case of extensive mandibular reconstructions.

Systematizing mandibular reconstruction using the resin frame method

Aims: Oral tumors are the most frequent diseases that lead to mandibular defects, but because they are so rare, it is difficult to obtain the necessary large capital investment to establish and introduce a mandibular reconstruction system. Therefore, we developed the Resin Frame method within the current facilities that objectively increases mandibular reproducibility without requiring advanced techniques. Methods: Subjects comprised 25 patients who underwent mandibular reconstruction by the resin frame method in the Department of Dentistry, Oral and Maxillofacial Surgery at Jichi Medical University Hospital between October 2013 and August 2015, and 25 patients who underwent the mandibular reconstruction by the conventional method between September 2007 and November 2011. All mandibles were reconstructed using fibula or iliac bones with a reconstruction plate. The computed tomography (CT) Digital Imaging and Communications in Medicine (DICOM) data before and after the operation were saved. Then, the layer function was used to fuse the pre- and postoperative CT images. Based on measured area, the concordance rate that is matching percentages between pre- and postoperative mandibles were calculated. We evaluated the difference between the concordance rate of the Resin Frame method and the conventional method of mandibular reconstruction. Results: Concordance rates for the resin frame method and conventional surgery were 75.09±6.09% and 67.39±13.44%, respectively, showing a significant difference (p=0.032, p lessthan 0.05). Conclusion: The resin frame method represents a mandibular reconstruction system that increases reproduction accuracy and can be implemented at current facilities using simple, objective techniques.

Evaluation of Clinical Outcomes of Osseointegrated Dental Implantation of Fibula Free Flaps for Mandibular Reconstruction.

Dental implantation has been used for oral rehabilitation to improve cosmesis and function. We aim to evaluate the clinical outcomes and success rates of primary and secondary dental implant placement in vascularized fibula bone grafts used for segmental mandibulectomy defects. A retrospective review was performed between November 2005 and July 2014 on all patients undergoing both fibula free tissue reconstruction of mandibular defects and endosseous dental implantation at an academic tertiary care referral hospital. Either primary (n = 20) or secondary (n = 26) dental implantation of the fibula was performed. Timing of implantation, location of implants, history of tobacco, alcohol, and radiation, reason for mandibulectomy, and outcomes related to these parameters. Forty-six patients (31 males, 15 females; mean age, 58.0 years) underwent dental implantation to the fibula graft. A total of 227 implants were placed, with a mean of 5 implants per patient (range, 2-7). Of these, 44 were placed into native mandible and 183 into fibula flap. Twenty patients underwent primary implantation and received 96 implants, while 26 patients underwent secondary implantation and received 131 implants. There were no flap failures and 22 implant-related complications in 16 patients (implant failure, n = 10; granulation or soft-tissue overgrowth, n = 6; exposed bone around implant, n = 6). An implant failure occurred in 10 patients (22%) resulting in removal of 15 implants. Nine of these patients underwent successful dental rehabilitation, 5 without further implantation, and 4 with replaced implants. One patient was not rehabilitated secondary to failed implantation. Therefore, there was a 93% overall implant survival rate (n = 212) and 98% overall implant-supported prosthesis success rate (n = 45) at a mean follow-up of 22 months. There was no difference in implant survival between primary (94%) (n = 90) and secondary (93%) (n = 122) implantation. Neither a history of preimplant or postimplant radiation exposure nor the diagnosis of osteoradionecrosis affected implant survival. Osseointegrated dental implantation is a relatively safe procedure with few complications. Vascularized fibula grafts are a suitable method of mandibular reconstruction and are amenable to successful primary and secondary endosseous implantation. 4.