Design and Fabrication of Implants for Mandibular and Craniofacial Defects Using Different Medical-Additive Manufacturing Technologies: A Review.

Mandibular and craniofacial bone defects can be caused by trauma, inflammatory disease, and benign or malignant tumors. Patients with bone defects suffer from problems with aesthetics, speech, and mastication, resulting in the need for implants. Conventional methods do not always provide satisfactory results. Most of the techniques proposed by researchers in the field of biomedical engineering use reverse engineering, computer-aided design (CAD), and additive manufacturing (AM), whose implementation can improve the outcomes of reconstructive surgeries. Several literature reviews on this particular topic have been conducted. However, they provide mostly overviews of AM technologies for general biomedical devices. This paper summarizes the use of existing medical AM techniques for the design and fabrication of mandibular and craniofacial implants, and then discusses their advantages and disadvantages in terms of accuracy, costs, energy consumption, and production rate. The aim of this study is to present a comparative review of the most commonly used AM technologies to aid researchers in selecting the best possible AM technologies for medical use. Studies included in this review contain CAD designs of mandibular or cranial implants, as well as their fabrication using AM technologies. Special attention is paid to PolyJet technology, because of its high accuracy, and economical efficiency.

Study of cerebrospinal injuries by force transmission secondary to mandibular impacts using a finite element model.

Brain and cervical injuries are often described after major facial impacts but rarely after low-intensity mandibular impacts. Force transmission to the brain and spinal cord from a mandibular impact such as a punch was evaluated by the creation and validation of a complete finite element model of the head and neck. Anteroposterior uppercut impacts on the jaw were associated with considerable extension and strong stresses at the junction of the brainstem and spinal cord. Hook punch impacts transmitted forces directly to the brainstem and the spinal cord without extension of the spinal cord. Deaths after this type of blow with no observed histological lesions may be related to excessive stressing of the brainstem, through which pass the sensory-motor pathways and the vagus nerve and which is the regulatory center of the major vegetative functions. Biological parameters are different in each individual, and by using digital modeling they can be modulated at will (jaw shape, dentition…) for a realistic approach to forensic applications.

Dipyridamole Augments Three-Dimensionally Printed Bioactive Ceramic Scaffolds to Regenerate Craniofacial Bone.

BACKGROUND: Autologous bone grafts remain a standard of care for the reconstruction of large bony defects, but limitations persist. The authors explored the bone regenerative capacity of customized, three-dimensionally printed bioactive ceramic scaffolds with dipyridamole, an adenosine A2A receptor indirect agonist known to enhance bone formation. METHODS: Critical-size bony defects (10-mm height, 10-mm length, full-thickness) were created at the mandibular rami of rabbits (n = 15). Defects were replaced by a custom-to-defect, three-dimensionally printed bioactive ceramic scaffold composed of ß-tricalcium phosphate. Scaffolds were uncoated (control), collagen-coated, or immersed in 100 µM dipyridamole. At 8 weeks, animals were euthanized and the rami retrieved. Bone growth was assessed exclusively within scaffold pores, and evaluated by micro-computed tomography/advanced reconstruction software. Micro-computed tomographic quantification was calculated. Nondecalcified histology was performed. A general linear mixed model was performed to compare group means and 95 percent confidence intervals. RESULTS: Qualitative analysis did not show an inflammatory response. The control and collagen groups (12.3 ± 8.3 percent and 6.9 ± 8.3 percent bone occupancy of free space, respectively) had less bone growth, whereas the most bone growth was in the dipyridamole group (26.9 ± 10.7 percent); the difference was statistically significant (dipyridamole versus control, p < 0.03; dipyridamole versus collagen, p < 0.01 ). There was significantly more residual scaffold material for the collagen group relative to the dipyridamole group (p < 0.015), whereas the control group presented intermediate values (nonsignificant relative to both collagen and dipyridamole). Highly cellular and vascularized intramembranous-like bone healing was observed in all groups. CONCLUSION: Dipyridamole significantly increased the three-dimensionally printed bioactive ceramic scaffold's ability to regenerate bone in a thin bone defect environment.

Traumatic dislocation of the mandibular condyle into the middle cranial fossa treated by an intraoral approach.

Dislocation of the mandibular condyle is one of several consequences of facial trauma that can be anticipated. The condylar neck is inherently weak and likely to fracture at the time of impact before dislocating into the middle cranial fossa. A review of the literature revealed that most cases of dislocation of the mandibular condyle into the middle cranial fossa are treated by open reduction and internal fixation via an extraoral approach or are treated conservatively with closed reduction. An intraoral approach is rare. Here we present a patient with traumatic dislocation of the mandibular condyle into the middle cranial fossa who was treated successfully by condylectomy and coronoidectomy through an intraoral approach and intermaxillary fixation followed by mouth-opening exercises and rehabilitation. Stable occlusion and movement of the mandible was achieved and the long-term results have been good. The intraoral approach may be an option in patients with traumatic dislocation of the mandibular condyle into the middle cranial fossa.

Localized low-dose rhBMP-2 is effective at promoting bone regeneration in mandibular segmental defects.

At least 26% of recent battlefield injuries are to the craniomaxillofacial (CMF) region. Recombinant human bone morphogenetic protein 2 (rhBMP-2) is used to treat CMF open fractures, but several complications have been associated with its use. This study tested the efficacy and safety of a lower (30% recommended) dose of rhBMP-2 to treat mandibular fractures. rhBMP-2 delivered via a polyurethane (PUR) and hydroxyapatite/ß-tricalcium phosphate (Mastergraft®) scaffold was evaluated in a 2 cm segmental mandibular defect in minipigs. Bone regeneration was analyzed at 4, 8, and 12 weeks postsurgery using clinical computed tomography (CT) and rhBMP-2, and inflammatory marker concentrations were analyzed in serum and surgery-site drain effluent. CT scans revealed that pigs treated with PUR-Mastergraft® + rhBMP-2 had complete bone bridging, while the negative control group showed incomplete bone-bridging (n = 6). Volumetric analysis of regenerated bone showed that the PUR-Mastergraft® + rhBMP-2 treatment generated significantly more bone than control by 4 weeks, a trend that continued through 12 weeks. Variations in inflammatory analytes were detected in drain effluent samples and saliva but not in serum, suggesting a localized healing response. Importantly, the rhBMP-2 group did not exhibit an excessive increase in inflammatory analytes compared to control. Treatment with low-dose rhBMP-2 increases bone regeneration capacity in pigs with mandibular continuity defects and restores bone quality. Negative complications from rhBMP-2, such as excessive inflammatory analyte levels, were not observed. Together, these results suggest that treatment with low-dose rhBMP-2 is efficacious and may improve safety when treating CMF open fractures. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 1491-1503, 2019.

Electric Saw Face Self-Mutilation in a 22-Year-Old Schizophrenic Man: Case Report.

Schizophrenia is a debilitating psychiatric disorder that affects a large segment of the population. It is managed mainly through pharmacotherapy, and family engagement is mandatory in the process. We present a case of self-mutilation in a 22-year-old man who cut his mandible with an electric saw, trying to modify his chin to better his appearance.

A Patient With Severe Lower Face Degloving Injury.

Avulsions of mandible are among the most devastating lesions observed in cranio-maxillofacial traumas. They present an important health problem because of the high risk of morbidity related to deformities that cause functional limitations and esthetic changes. The avulsions commonly result from high-energy effects, which cause complete or partial separation of the mandibular bone of the face. As a result of the intense aggression, the skin and subcutaneous tissues of the bone are usually removed, affecting muscles, fascia, blood vessels, and the surrounding nerves. This article aimed to present a case of partial avulsion of mandible caused by car accident. Here, we emphasize the importance of correctly performing patient stabilization and maintenance of the airways, damage control, and facial reconstruction. Finally, we proceeded with a literature review to discuss standard protocols and controversies in the treatment of these lesions.

The Use of Computer-Aided Design and Manufacturing in Acute Mandibular Trauma Reconstruction.

PURPOSE: Virtual surgical planning (VSP) with subsequent computer-aided design and manufacturing have proved efficacious in improving the efficiency and outcomes of a plethora of surgical modalities, including mandibular reconstruction and orthognathic surgery. PATIENTS AND METHODS: Five patients underwent complex mandibular reconstruction after traumatic injury using VSP from July 2016 to August 2017 at our institution. The Johns Hopkins University Hospital institutional review board approved the present study. The patient's occlusion was restored virtually, and a milled 2.0-mm plate was created that would bridge the defect with the patient in occlusion. RESULTS: Appropriate occlusion was confirmed using postoperative computed tomography. No patient developed any adverse outcomes, except for a minor dehiscence of the intraoral incision in 1 patient that was treated with local wound care. The average interval from the injury to custom plate availability was approximately 7 days. CONCLUSIONS: The utility of this technology in acute complex mandibular trauma can overcome the challenges of traditional treatment. Custom patient-specific prebent and milled plates permit the use of a lower profile and therefore less palpable hardware, can guide reduction, avoid the need for plate bending, and obviate the need for an extraoral incision.

Imaging of Dentoalveolar and Jaw Trauma.

Prior to the invention of cone beam CT, use of 2-D plain film imaging for trauma involving the mandible was common practice, with CT imaging opted for in cases of more complex situations, especially in the maxilla and related structures. Cone beam CT has emerged as a reasonable and reliable alternative considering radiation dosage, image quality, and comfort for the patient. This article presents an overview of the patterns of dental and maxillofacial fractures using conventional and advanced imaging techniques illustrated with multiple clinical examples selected from the author's oral and maxillofacial radiology practice database.

Customized hybrid biomimetic hydroxyapatite scaffold for bone tissue regeneration.

Three-dimension (3D) scaffolds for bone tissue regeneration were produced combining three different phases: nanometric hydroxyapatite (HA) was synthesized by precipitation method and the crystals nucleation took place directly within collagen fibrils following a biologically inspired mineralization process; polycaprolactone was employed to give the material a 3D structure. The chemico-physical analysis carried out to test the material's properties and composition revealed a high similarity in composition and morphology with biologically mineralized collagen fibrils and a scaffold degradation pattern suitable for physiological processes. The micro- computerized tomography (micro-CT) showed 53.53% porosity and a 97.86% mean interconnected pores. Computer-aided design and computer-aided manufacturing (CAD-CAM) technology was used for molding the scaffold's volume (design/shape) and for guiding the surgical procedure (cutting guides). The custom made scaffolds were implanted in sheep mandible using prototyped surgical guides and customized bone plates. After three months healing, scanning electron microscopy (SEM) analysis of the explanted scaffold revealed a massive cell seeding of the scaffold, with cell infiltration within the scaffold's interconnected pores. The micro-CT of the explanted construct showed a good match between the scaffold and the adjacent host's bone, to shield the implant primary stability. Histology confirmed cell penetration and widely documented neoangiogenesis within the entire scaffold's volume. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 723-734, 2017.

Octacalcium phosphate collagen composite facilitates bone regeneration of large mandibular bone defect in humans.

Recently it was reported that the implantation of octacalcium phosphate (OCP) and collagen composite (OCP-collagen) was effective at promoting bone healing in small bone defects after cystectomy in humans. In addition, OCP-collagen promoted bone regeneration in a critical-sized bone defect of a rodent or canine model. In this study, OCP-collagen was implanted into a human mandibular bone defect with a longer axis of approximately 40 mm, which was diagnosed as a residual cyst with apical periodontitis. The amount of OCP-collagen implanted was about five times greater than the amounts implanted in previous clinical cases. Postoperative wound healing was satisfactory and no infection or allergic reactions occurred. The OCP-collagen-treated lesion was gradually filled with radio-opaque figures, and the alveolar region occupied the whole of the bone defect 12 months after implantation. This study suggests that OCP-collagen could be a useful bone substitute material for repairing large bone defects in humans that might not heal spontaneously. Copyright © 2015 John Wiley & Sons, Ltd.

Discovery from a lateral oblique radiograph.

In many oral and maxillofacial surgery units and emergency departments, lateral oblique radiographs are not routinely included in radiological investigations for suspected mandibular fractures because orthopanoramic and posteroanterior mandible views usually suffice. This paper reports a case where a lateral oblique radiograph proved to be very useful in managing a fractured atrophic mandible. This case report highlights the importance of considering the use of alternative radiographs for suspected fracture(s) of an atrophic mandible to exclude the unexpected.

Local administration of stromal cell-derived factor-1 promotes stem cell recruitment and bone regeneration in a rat periodontal bone defect model.

Stromal cell-derived factor-1 (SDF-1) recruits adult stem/progenitor cells via its specific receptor, C-X-C motif receptor 4 (CXCR4), to promote heart, kidney and tendon regeneration, but little is known about the effects of SDF-1 on bone regeneration in periodontal diseases. The objective of this study was to investigate whether local administration of SDF-1 in a collagen membrane scaffold enhanced the recruitment of host stem cells and improved periodontal bone defect repair. To this end, bone defects were established on the buccal side of bilateral mandibles in Wistar rats. After application of collagen membranes loaded with SDF-1 or phosphate-buffered saline (PBS) to the defects, the effects of SDF-1 on stem cell recruitment, inflammatory cell responses, angiogenesis, osteoclastogenesis, scaffold degradation, and bone regeneration were evaluated. It showed that SDF-1 recruited host-derived mesenchymal stem cells and hematopoietic stem cells to the wound area and significantly reduced the CD11b+ inflammatory cell response. Moreover, SDF-1 increased vascular formation, induced early bone osteoclastogenesis, accelerated scaffold degradation, and promoted the quality and quantity of regenerated bone. Our results suggest that this cell-free approach by local administration of SDF-1 may be an effective strategy for development as a simple and safe technique for periodontal bone regeneration.

Mandibular Nonvascularized Bone Grafts of Critical Sizes and Complex Warfare Defects With Interrami Intraoral Fixation.

The reconstruction of mandibular bone grafts of critical size complex defects and posterior segments malpositioned due to modern warfare injuries is a difficult, challenging task. The condition becomes even more complex if primary reconstruction is carried out inexpertly, which leads to severe disfigurement, rami mesial superior shift, tongue prolapsed, loss of speech, etc.A new interrami intraoral Kirschner wire fixation (IRIF) technique is presented for the reconstruction of large mandibular defects by nonvascularized iliac bone grafts. Twelve symphysis, parasymphysis, and lateral mandibular avulsed or chopped off with bone loss ranging from 5 cm to "ear-to-ear" rami defects underwent nonvascularized iliac bone block graft. A direct stainless steel wire fixation was carried out between bone blocks and original bone. Indirect rigid fixations were applied using a 2-mm horseshoe-shaped K-wire IRIF technique. Two complications were reported: one due to infection and the other due to the mucosa dehiscing where 2 cm of sequestrated bone was removed. The biomechanics (stress/strain distribution and strength) along the K-wire substitute the tension on the alveolar part of the mandible, creating a zone of resistance in the rami zone. This successful bone healing between the mandibular bone and the graft may have resulted from prolonged periods of sufficient stabilization during function of the mandible and bone graft function as one mandible unit during the healing period by IRIF. This new technique is quick, cheap, easy, and well tolerated by the patient for many months without complications and has been successful in modern warfare reconstructions of mandibular bone graft large defects.

Treatment of traumatic dislocation of the mandibular condyle into the cranial fossa: development of a probable treatment algorithm.

This study summarizes our experience of treating three rare cases of traumatic superior dislocation of the mandibular condyle into the cranial fossa and provides a potential treatment algorithm. Between the years 2002 and 2012, three patients with traumatic superior dislocation of the mandibular condyle into the cranial fossa were admitted to our department. After evaluating the interval from injury to treatment, the associated facial injuries including neurological complications, and the computed tomography imaging findings, an individualized treatment plan was developed for each patient. One patient underwent closed reduction under general anaesthesia. Two patients underwent open reduction with craniotomy and glenoid fossa reconstruction. All three patients were followed up for 1 year. Mouth opening and occlusal function recovered well, but all patients had mandibular deviation during mouth opening. Closed reduction under general anaesthesia, open surgical reduction with craniotomy, and mandibular condylotomy are the three main treatment methods for traumatic superior dislocation of the mandibular condyle into the cranial fossa. The treatment method should be selected on the basis of the interval from injury to treatment, associated facial injuries including neurological complications, and computed tomography imaging findings.

Features and management of intracranial mandibular condyle dislocation after trauma.

BACKGROUND: Dislocation of the mandibular condyle into the middle cranial fossa is rare in clinics. It often occurs when the mouth is open wide during the injury. It causes restriction of mandibular motion, lower facial asymmetry, pain in the temporomandibular joint (TMJ), etc. OBJECTIVE: To introduce the features of intracranial mandibular condyle dislocation and discuss the management to this kind of trauma. MAJOR FINDINGS: In this paper, the authors present two cases, describing the diagnosis, surgical management, and 1-year follow-up evaluation. The results of the authors' treatment to intracranial mandibular condyle dislocation were satisfactory and stable, and no surgical complications were detected. CONCLUSION: Advanced imaging studies are mandatory for exact diagnosis and successful treatment of intracranial mandibular condyle dislocation, and individualized management is recommended.

An underestimated "ghost" foreign body as an unusual cause of mandibular osseocutaneous fistula formation: impacted spike of a soccer cleat.

In this article, the case of a patient with osteocutaneous fistula at the left malar region secondary to impacted spike of a soccer cleat to the mandible is presented. Both the clinical and radiologic diagnoses failed because of an obscure anamnesis of the patient and the unavailability of viewing the spike in orthopantomogram and computed tomography. Surgical extirpation was performed to the 41-year-old man who was injured in a football match 3 months before the presentation and had a swooning history after an accidental booting. There were no early or late complications after the surgery at the end of 9 months. This study shows the importance of both obtaining a definite history of patients and sequential radiologic imaging to make a differential diagnosis between the foreign bodies and cystic or noncystic tumors and inflammatory lesions of the mandible.

Defining the critical-sized defect in a rat segmental mandibulectomy model.

IMPORTANCE: Advances in tissue engineering offer potential alternatives to current mandibular reconstructive techniques; however, before clinical translation of this technology, a relevant animal model must be used to validate possible interventions. OBJECTIVE: To establish the critical-sized segmental mandibular defect that does not heal spontaneously in the rat mandible. DESIGN AND SETTING: Prospective study of mandibular defect healing in 29 Sprague-Dawley rats in an animal laboratory. INTERVENTIONS: The rats underwent creation of 1 of 4 segmental mandibular defects measuring 0, 1, 3, and 5 mm. All mandibular wounds were internally fixated with 1-mm microplates and screws and allowed to heal for 12 weeks, after which the animals were killed humanely. MAIN OUTCOMES AND MEASURES: Analysis with micro-computed tomography of bony union and formation graded on semiquantitative scales. RESULTS: Seven animals were included in each experimental group. No 5-mm segmental defects successfully developed bony union, whereas all 0- and 1-mm defects had continuous bony growth across the original defect on micro-computed tomography. Three of the 3-mm defects had bony continuity, and 3 had no healing of the bony wound. Bone union scores were significantly lower for the 5-mm defects compared with the 0-, 1-, and 3-mm defects (P < .01). CONCLUSIONS AND RELEVANCE: The rat segmental mandible model cannot heal a 5-mm segmental mandibular defect. Successful healing of 0-, 1-, and 3-mm defects confirms adequate stabilization of bony wounds with internal fixation with 1-mm microplates. The rat segmental mandibular critical-sized defect provides a clinically relevant testing ground for translatable mandibular tissue engineering efforts.

Agujero mentoniano doble / Double mental foramina

The knowledge of the location, trajectory, and characteristics of the neurovascular bundles in the jaws is fundamental to reduce risk of injuries to this structure during surgical procedures, especially when anatomical variations are present. The presence of anatomical variations associated with the mental foramen has been reported in some cases and is frequently undervalued in clinical procedures. Sensorial disturbances, such as paresthesia in the lower lip or cheeks, may occur as result of pressure on the mental foramen. These anatomical variations can be detected in clinical practice by imaging exams. Computed tomography has been established as a valuable imaging modality capable of providing in-depth information about maxillofacial structures, allowing detailed evaluation of their topography and anatomical variations, such as additional mental foramina. The objective of this article was to describe a case with double mental foramina that only could be observed in computed tomography images. The use of cone beam computed tomography has increased in dentistry, thus anatomical variations that may have an influence on the diagnosis and treatment planning must be recognized. Have a good knowledge of additional mental foramina may contribute to adequate anesthetic techniques and to avoid misdiagnosis of bone lesions and eventual damages to the nerves and vessel during surgical procedures in that region(AU)

El conocimiento de la ubicación, trayectoria y características de los haces neurovasculares en la mandíbula es de fundamental importancia para reducir el riesgo de lesión en estas estructuras durante procedimientos quirúrgicos, especialmente cuando hay presencia de variaciones anatómicas. La presencia de estas variaciones anatómicas relacionadas con el agujero mentoniano ha sido reportada en algunos casos y no es frecuentemente valorada en los procedimientos clínicos. Alteraciones sensoriales, tales como parestesias en el labio inferior o en las mejillas, pueden ocurrir como resultado de la presión en el agujero mentoniano. Estas variaciones anatómicas pueden ser detectadas en la práctica clínica a través de los exámenes de diagnóstico por imágenes. La tomografía computarizada se ha establecido como una técnica de imagen útil capaz de proporcionar información detallada de las estructuras maxilofaciales, lo que permite una evaluación minuciosa de su topografía y de las variaciones anatómicas, tales como el agujero mentoniano accesorio. El objetivo de este artículo es describir un caso con agujeros mentonianos dobles que solo pudieron ser observados en las imágenes de tomografía computarizada. El uso de la tomografía computarizada de haz cónico se ha incrementado en la odontología, así las variaciones anatómicas que pueden tener influencia sobre el diagnóstico y planificación del tratamiento pueden ser conocidas. El conocimiento de los forámenes mentonianos adicionales puede contribuir a una adecuada técnica de anestesia y evitar errores diagnósticos de lesiones óseas y daño eventual de los nervios y vasos durante procederes quirúrgicos en la región(AU)