Non-vascularised iliac crest bone graft for immediate reconstruction of lateral mandibular defect

Hoxc10-mediated 'positional memory' regulates cartilage formation subsequent to femoral heterotopic grafting

The Hox gene plays a crucial role in the bone development, determining their structure and morphology. Limb bone grafts expressing Hox positive genes are commonly used for free transplantation to repair Hox negative mandibular critical bone defects. However, the specific role of original Hox genes in newly formed bone during the cross-layer bone grafting healing process remains unexplored. Our findings demonstrate that femurs ectopically grafted into the mandibular environment retained a significant ability to differentiate into cartilage and form cartilaginous callus, which may be a key factor contributing to differences in bone graft healing. Hoxc10, an embryonic layer-specific genes, regulates cartilage formation during bone healing. Mechanistically, we observed Hoxc10 retention in co-cultured femoral BMSCs. Knocking out Hoxc10 narrows the bone gap and reduces cartilage formation. In summary, we reveal Hoxc10's 'positional memory' after adult cross-layer bone graft, influencing the outcomes of autologous bone graft.

Versatility of Transport Distraction Osteogenesis for Reconstruction of Lateral Mandibular Ablative Defects

Introduction

The reconstitution of form and function after maxillofacial tumor resection or traumatic bony defects is a challenge when considering reconstructive options. The reconstructive options will depend upon whether the tissues to be replaced included bone alone or both bone and soft tissue (composite resection).

Methodology

This study was carried out on nine patients who with benign tumors or cysts of the mandible that required segmental resection. Mandibular reconstruction using mandibular transport distraction osteogenesis was performed for all the cases. Depending on whether the condyle was spared or sacrificed, the type of mandibular transport distractor either fixed on the remnant condyle-ramus unit or had a condylar component replacing the resected condyles. Depending on the location of the defect, transport distraction was carried our anterior to posterior or posterior to anterior.

Results

A total of nine cases of benign mandibular pathologies were operated. Segmental resection with condylar preservation was carried out in seven cases, segmental resection with condylar resection was carried out in two cases. In cases with condylar resection, the reconstruction plate of the distractor device had a condylar component. Anterior to posterior transport distraction was carried out in seven cases, and posterior to anterior transport distraction carried out in two cases. The amount of distracted bone ranged from 38 to 46 mm.

Conclusion

Mandibular transport distraction osteogenesis offers a modality of reconstruction where the patient's native host bone is osteotomized and gradually distracted to induce the formation of regenerated osseous structure and soft tissue. Being cost-effective, not requiring a steep learning curve/long operative time, and not technically demanding as vascularized bone grafts/flaps, it is feasible in the Indian setup as a practical reconstructive option for benign jaw tumors.

Use of customized 3-dimensional printed mandibular prostheses with a dental implant pressure-reducing device in mandibular body defect: A finite element study performing multiresponse surface methodology

Background/purpose

Segmental body defects of the mandible result in the complete loss of the affected region. In our previous study, we investigated the clinical applicability of a customized mandible prosthesis (CMP) with a pressure-reducing device (PRD) in an animal study. In this study, we further incorporated dental implants into the CMP and explored the use of dental implant PRD (iPRD) designs.

Materials and methods

By employing a finite element analysis approach, we created 4 types of CMP: CMP, CMP with iPRD, CMP-PRD, and CMP-PRD with iPRD. We developed 2 parameters for the iPRD: cone length (CL) in the upper part and spring pitch (SP) in the lower part. Using the response surface methodology (RSM), we determined the most suitable structural assignment for the iPRD.

Results

Our results indicate that CMP-PRD had the highest von Mises stress value for the entire assembly (1076.26 MPa). For retentive screws and abutments, CMP with iPRD had the highest von Mises stress value (319.97 and 452.78 MPa, respectively). CMP-PRD had the highest principal stress (131.66 MPa) in the anterior mandible. The iPRD reduced principal stress in both the anterior and posterior mandible. Using the RSM, we generated 25 groups for comparison to achieve the most favorable results for the iPRD and we might suggest the CL to 12 mm and the SP to 0.4 mm in the further clinical trials.

Conclusion

Use of the PRD and iPRD in CMP may resolve the challenges associated with CMP, thereby promoting its usage in clinical practice.

Bone reconstruction of extensive maxillomandibular defects in adults

Reconstruction of significant maxillomandibular defects is a challenge that has been much discussed over the last few decades. Fundamental principles were developed decades ago (bone bed viability, graft immobilization). Clinical decision-making criteria are highly relevant, including local/systemic factors and incision designs, the choice of material, grafting technique, and donor site morbidity. Stabilizing particulated grafts for defined defects-that is, via meshes or shells-might allow significant horizontal and vertical augmentation; the alternatives are onlay and inlay techniques. More significant defects might require extra orally harvested autologous bone blocks. The anterior iliac crest is often used for nonvascularized augmentation, whereas more extensive defects often require microvascular reconstruction. In those cases, the free fibula flap has become the standard of care. The development of alternatives is still ongoing (i.e., alloplastic reconstruction, zygomatic implants, obturators, distraction osteogenesis). Especially for these complex procedures, three-dimensional planning tools enable facilitated planning and a surgical workflow.

Planning of physiotherapeutic procedure in patients after mandible reconstruction taking into account donor site: a literature review

BACKGROUND

Mandible tumors are very rare. One of the main methods of the treatments is resection of the tumor and then reconstruction of the mandible. The donor site is often distant tissue-fibula or ilium. Following this, it is necessary to improve the patient in two ways, on one hand restoring the function of the mandible, and on the other hand, improving the donor site area. For that reason, physiotherapy after tumor resection and reconstruction of the mandible is very complicated. The aim of this bibliographic review was to find the methods of the reconstruction of the mandible in the context of patients' functional assessment after surgeries to create effective physiotherapeutic procedures in the feature.

METHODS

PEDro, Medline (PubMed), Cochrane Clinical Trials were searched.

RESULTS

767 articles were found. 40 articles were included to this literature review.

CONCLUSIONS

Authors showed different kinds of surgeries strategy for patients with tumors of the mandible. They also showed manners of patients' functional assessment in the localization of transplantation and donor site. It could be useful for physiotherapists during planning of comprehensive physiotherapy.

Tenants of Mandibular Reconstruction in Segmental Defects

The premises of mandibular reconstruction are the restoration of occlusion and mandibular contour for the purpose of preserving the facial identity, oral airway, and effective speech and mastication. Establishing functional occlusion is the primary tenant in all mandibular reconstruction. In cases of segmental defects, particularly in dentate regions of the mandible, there has been a paradigm shift over the past two decades in how surgeons are approaching the restoration of load-bearing mandibular continuity with capacity for dental implantation. Here we discuss considerations for deciding the most effective method of reconstruction in segmental defects.

The Use of Customized Three-Dimensionally Printed Mandible Prostheses with a Pressure-Reducing Device: A Finite Element Analysis in Different Chewing Positions, Biomechanical Testing, and In Vivo Animal Study Using Lanyu Pigs

Segmental bony defects of the mandible constitute a complete loss of the regional part of the mandible. Although several types of customized three-dimension-printed mandible prostheses (CMPs) have been developed, this technique has yet to be widely used. We used CMP with a pressure-reducing device (PRD) to investigate its clinical applicability. First, we used the finite element analysis (FEA). We designed four models of CMP (P1 to P4), and the result showed that CMP with posterior PRD deployment (P4 group) had the maximum total deformation in the protrusion and right excursion positions, and in clenching and left excursion positions, posterior screws had the minimum von Mises stress. Second, the P4 CMP-PRD was produced using LaserCUSING from titanium alloy (Ti-6Al-4V). The fracture test result revealed that the maximum static pressure that could be withstood was 189 N, and a fatigue test was conducted for 5,000,000 cycles. Third, animal study was conducted on five male 4-month-old Lanyu pigs. Four animals completed the experiment. Two animals had CMP exposure in the oral cavity, but there was no significant inflammation, and one animal had a rear wing fracture. According to a CT scan, the lingual cortex of the mandible crawled along the CMP surface, and a bony front-to-back connection was noted in one animal. A histological examination indicated that CMP was significantly less reactive than control materials (p = 0.0170). Adequate PRD deployment in CMP may solve a challenge associated with CMP, thus promoting its use in clinical practice.

Use of anterior ramus bone graft for mandibular reconstruction in elderly patients

In this study, we investigated the feasibility of using a geometrically designed anterior ramus graft to reconstruct lateral mandibular defects. This was achieved by assessing the anatomical dimensions of the mandibular ramus on computed-tomographies. The design sequence and application of the graft was also demonstrated using one of our cases. The following dimensions were measured; a and b - horizontal length from mid-ramus to the posterior and anterior ramus border respectively, c - longest length of the graft, Mp - width at the centre of the ramus, h - vertical length of the angle at its cross-section, w - horizontal length of the angle at its cross-section, x - cross-sectional area along the mandible angle. A total of 80 mandibular rami were examined. The mean length of a, b, c were 17.3 ± 1.8 mm, 15.9 ± 1.2 mm, 54.6 ± 3.8 mm, respectively. The mean width of Mp was 9.8 ± 1.1 mm. The mean cross section area of Eo-Md (x) was 326.7 ± 67.8 mm². The average length of h and w were 26.5 ± 3.2 and 15.6 ± 2.1 mm, respectively. The use of virtual surgical planning (VSP) to geometrically design the graft was also described. Together with VSP, the anterior ramus bone graft will allow for reconstruction of the mandible with greater surgical efficiency, reduced complexity and without the need for extra-oral bone harvest. This may be an useful alternative in situations where simpler reconstructive procedures are preferred.

Free flaps for head and neck cancer in paediatric and neonatal patients

PURPOSE OF REVIEW

To review recent literature on the subject of free tissue transfer options in paediatric head and neck surgery, with a particular emphasis on highlighting the advantages and disadvantages of different reconstructions in the paediatric patient.

RECENT FINDINGS

Free tissue transfer in paediatric patients is predictable and applicable for a wide range of congenital and acquired defects in the head and neck. The free fibula flap is a mainstay of mandibular reconstruction and allows excellent implant-supported prosthodontic rehabilitation and growth potential at the recipient site with little or no donor site morbidity. Other less commonly explored options include the deep circumflex iliac artery flap, scapula flap and medial femoral condyle flap. The gracilis mucle remains the mainstay for facial reanimation with other options including pectoralis minor, rectus abdominis, extensor digitorum brevis and latissimus dorsi. There are compelling arguments for centralization of services and creative strategies in postoperative rehabilitation (e.g. play therapy).

SUMMARY

Free flaps in paediatric patients are a viable option and may even have advantages relative to adults because of the absence of atherosclerosis, purported lower risk of vasospasm and proportionally larger vessel size. Transfer earlier in life maximizes functional potential and 'normalizes' treatment.

Custom Implant for Reconstruction of Mandibular Continuity Defect

PURPOSE

The purpose of this study was to compare the daily food intake rate and the rate of screw loosening between 2 groups of rabbits with mandibular continuity defects: custom implant (CI) group and 5-hole mini-plate group.

MATERIALS AND METHODS

Two types of cylindrical implants were printed, and their physical strength was compared. In this study using rabbits, 1 group (n = 5) received a CI for the reconstruction of a mandibular continuity defect (CI group) and the other group (n = 5) received a 5-hole mini-plate without a bone graft (reconstruction plate [RP] group). After reconstruction, the daily food intake rate and the rate of screw loosening were examined postoperatively. Histologic examination in the CI group was performed 3 months after the operation.

RESULTS

The design that mimicked the mandible showed greater physical strength. The amount of time required to achieve 50% recovery was shorter in the CI group than in the RP group (P = .011). The total number of loosened screws in the CI group was lower than that in the RP group at 3 months postoperatively (P = .008). New bone formation in the porous CI was evident in the CI group.

CONCLUSIONS

Rabbits with mandibular continuity defects treated with CIs for reconstruction showed faster recovery of the daily food intake rate and fewer loosened screws than those treated with a 5-hole mini-plate without bone graft.