A new vascularized mandible heterotopic transplant model for studies on the growth of condylar cartilage

PURPOSE

We developed a vascularized mandibular heterotopic transplant (VMHT) model to allow the observation of condylar cartilage growth in the absence of external and dynamic factors, such as mastication.

MATERIALS AND METHODS

In VMHT, we performed a transplantation between 2 age-matched inbred rats (male Lewis rats aged 6 weeks). The hemimandibular tissue, with the common carotid artery and external jugular vein as vascular pedicle, was harvested from the donor rat and transplanted to the neck of the recipient rat with the use of vascular anastomosis under an operating microscope. To evaluate the stability of VMHT, we investigated both the weight change of the recipient rats and the blood circulatory conditions of the grafts via the radioactive microsphere method, laser Doppler blood flowmeter, and angiography.

RESULTS

Although the body weight of the recipient rats decreased immediately after transplantation, these values subsequently increased, indicating a good nutritional environment in the recipient rat. Also, the VMHT graft tissue and the mandibular condyle had favorable blood circulation, equivalent to normal conditions.

CONCLUSIONS

In VMHT, transplantation between the 2 age-matched inbred rats using anastomosis of the similar blood vessels enables us to minimize the influences of genetic factors, hemodynamics, hormones, and other external factors. Our investigation indicated that the transplant possessed favorable growth conditions, equivalent to the environment of the endogenous mandibular condyle. Thus, we are able to maintain conditions similar to the normal environment of the mandibular condyle. This model will be very useful in future investigations of the influences of external and functional factors on chondrogenesis and enchondral ossification of the mandibular condyle.

Implant placement above a bifurcated mandibular canal: a case report

Accurate radiographic assessment of available bone dimension superior to the mandibular canal is essential to the favorable placement of dental implants. Panoramic and periapical radiography are the standard of care. They typically offer a clinically adequate interpretation of the canal topography. However, in about 1% of patients, the mandibular canal may bifurcate. This may or may not be seen on panoramic or periapical films. A case report is presented that uses complex motion tomography as an aid to proper implant placement above a bifurcated mandibular canal.

Prenatal morphogenesis of the human mental foramen

The mental foramen, at first glance, merely looks like a hole where the mental nerve and the vascular bundle runs through. From a morphogenetic point of view, however, the mental foramen is a suitable model to study the development of a structure where different components are involved. To understand this developmental process, a three-dimensional description at different developmental stages first has to be given. From histological serial sections of human embryos and fetuses, ranging in size from 19 to 117 mm crown rump length (CRL), three-dimensional reconstructions of the foraminar regions were made. Outline and form of the developing foramen, size, course of the mental nerve and the adjacent blood vessels could be shown in detail. In this way, the formation of these structures became concrete in three dimensions. In the future, to understand the mechanisms regulating this complex system, where a nerve and blood vessels became successively surrounded by bone, molecular biological data have to be correlated with morphological findings.

Microvascular temporomandibular joint and mandibular ramus reconstruction in hemifacial microsomia

Microvascular temporomandibular joint (TMJ) and mandibular ramus reconstruction was performed in a 4-year-old hemifacial microsomia patient with multiple craniofacial and extracranial anomalies (Goldenhar syndrome). Her major craniofacial anomalies included bilateral cleft lip and palate, left macrostomia, left microtia, and complete absence of the left vertical mandibular ramus and TMJ. Most of her other anomalies had been corrected surgically before TMJ and vertical mandibular ramus reconstruction, which was accomplished with a metatarsophalangeal (MTP) joint transplantation. The MTP joint was placed in hyperextended position in the skull base inserting the proximal phalanx under the remnants of the zygomatic arch and replacing the vertical mandibular ramus with the metatarsal bone. Straight mouth opening, correction of the midline, and normalized lateral movements of the mandible were accomplished. The graft includes two epiphyseal plates, which should maintain growth of the transplant. During the follow-up period (16 months) the achieved results have been maintained without adverse effects. The present technique appears to be a promising alternative in the treatment of children with Pruzansky type 3 hemifacial microsomia.

[Vascular complications after cranio-facial trauma]

Despite recent advances in automobile safety, facial trauma remains a common event. Cranio-facial trauma, which usually occurs within a context of multiple trauma, can, in some patients, lead to serious life-threatening vascular complications. Such injury usually involves the carotid system (hemorrhage, aneurysm, dissection). Management of these vascular injuries must be given the same priority as other multiple trauma injuries. We present few typical cases illustrating carotid-cavernous or vertebro-vertebral fistulae, false aneurysms, arterial dissections or oro-facial bleeding. Bleeding is generally controlled by ligation or compression, other lesions being diagnosed secondarily by arteriography depending on the particular clinical situation. Treatment may involve endovascular procedures to achieve intravascular embolism or vascular occlusion.

[Life threatening oral hemorrhage after implantation into the distal right mandible]

In dental practice, surgical implant procedures are frequently conducted for pre-prosthetic surgery. Intra-operative complications are rare and can mostly be prevented effectively with adequate preparatory measures. However, not all risks can be anticipated a priori. Anatomical variation, such as variation in the path of blood vessels, is often unpredictable. This paper describes a life-threatening hemorrhage that occurred in a 60-year-old male during the insertion of an implant in the distal right mandible. It was impossible to stop the bleeding using local measures. Only extraoral ligation of the facial artery proved effective in suppressing the hemorrhage. The submentalis artery, a branch of the facial artery, had an atypical path directly below the caudal ridge of the mandible. The possibility of similar complications should make us re-evaluate preoperative preventive measures, and places greater demands on intra-operative complication prophylaxis. The international literature on this topic is discussed.

Comparative study of clinical manifestation, plain-film radiography, and computed tomographic scan in arteriovenous malformations of the jaws

OBJECTIVE

The purpose of this study was to summarize the clinical manifestation, plain-film radiography, and computed tomographic (CT) scan features of arteriovenous malformations (AVMs) of the jaws on the basis of a series of 12 patients.

STUDY DESIGN

This study group comprised twelve patients with AVM of the jaws from February 1996 to February 2001. Seven cases were located in the mandible, and 5 in the maxilla. Both plain-film radiography and CT scan were available for all cases. For the patients with lesions in the mandible, panoramic, posterioanterior, and lateral mandibular views were applied. Waters' position view and panoramic radiography were indicated for AVMs of the maxilla.

RESULTS

Each patient with AVM of the maxillary bone had involvement of adjacent soft tissues. Various radiographic signs were noted, including erosion, coarse trabeculae, and apparent lack of any radiographic change, and CT scans featured cystic expansion of alveolar process with broken cortex. The radiographic signs and CT scan features of AVMs in the mandible were related to involvement of surrounding soft tissues. If involvement of the adjacent soft tissues was found, "soap bubble" radiolucency was shown radiographically and osteolytic expansion with perforation of cortex was present on CT scan. In cases without surrounding soft tissue involvement, the various radiographic signs included multilocular or unilocular radiolucency or coarse trabeculae; osteolytic expansions with intact cortex were found on CT scan.

CONCLUSION

AVMs of the jaws showed intraosseous osteolytic expansion on CT scan but had variable appearance on plain-film radiographs.

Assessment of efficacy of endovascular embolization for central arteriovenous malformations (AVM) in the jaw

OBJECTIVE

To study the angiographic properties of central AVMs in the jaw, and to investigate the efficacy of embolization of them.

METHODS

Eleven cases of central AVMs underwent angiography and embolization, nine cases experienced surgery after embolization, and the other two cases were embolized alone; all these cases were followed up after treatment. The angiographic features and embolization results were analyzed.

RESULTS

Large venous pouches were angiographically opacified in 9 of 11 AVMs. Of the nine operated cases, curettage was safely performed. The intraoperative bleeding was evidently decreased, and the continuity of the jaw was preserved. Five of these operated cases were free of recurrence during 18 - 27 months in follow-up. The two cases embolized alone were free of recurrence during 24 months' follow-up.

CONCLUSIONS

Via arterial and venous approaches, embolization could greatly decrease the intraoperative bleeding and thus help to preserve the continuity and potentiality of development of the jaw for intraosseous AVMs, moreover, it may be curative in some cases.

Appearance, location, course, and morphology of the mandibular incisive canal: an assessment on spiral CT scan

OBJECTIVES

To assess the appearance, location, and course of the incisive canal as compared to other anatomical landmarks on spiral CT of the mandible.

METHODS

Study material included 230 spiral CT scans taken for preoperative planning of implant placement in the posterior mandible. All scanning was performed using a standard exposure and patient positioning protocol. Axial, panoramic, and reformatted cross-sectional images were carefully examined. Visibility of the incisive canal and other anatomical landmarks was scored using a four-point rating scale. The vertical and buccolingual diameter of the outer contour as well the diameter of the inner contour of the incisive canal were measured using a digital sliding caliper.

RESULTS

An incisive canal was identified in 93% of the cases, with good visibility in 22% of the cases. Mean (s.d.) vertical diameter, buccolingual diameter, and inner diameter of the incisive canal were 4.7 (1.1), 3.7 (0.7), and 1.1 (0.3) mm respectively. The mandibular canal, mental foramen, lingual foramen, and anterior looping appeared in 98, 100, 82 and 7% of the images respectively.

CONCLUSIONS

A well-defined incisive canal could be detected in the majority of spiral CT scans. Its radiographic detection remained lower than for the mandibular canal or mental foramen, but higher than for the visibility of the lingual foramen. Visualisation of the incisive canal and the occasional presence of an anterior looping, demonstrates the potential value of cross-sectional imaging of the anterior mandible for presurgical planning purposes.

The location of parotid gland tumors in relation to the facial nerve on magnetic resonance images and computed tomography scans

PURPOSE

The facial nerve, which cannot be visualized radiographically in its intraparotid part, divides the parotid gland into 2 lobes. When planning surgery, it is important to know where to locate a parotid gland tumor in relation to the facial nerve, because the location can influence the duration and difficulty of the operation. In this study, an anatomic line that predicts the course of the facial nerve in the parotid gland, is applied clinically and compared with another line recently described to evaluate the usefulness of both tools in the use of computed tomography scans and magnetic resonance images.

MATERIALS AND METHODS

We reviewed 28 scans (15 computed tomography and 13 magnetic resonance) and used both lines to predict tumor location in the parotid gland. The accuracy of each prediction was checked later by referring to the surgical report.

RESULTS

This new anatomic line helped us to correctly predict tumor location in relation to the facial nerve in 24 cases (85.7%), whereas the other line was helpful in 20 cases (71.4%).

CONCLUSION

Our new line may be a very useful tool to predict the location of parotid gland tumors.

Embolization of the AVM of jaws by direct percutaneous puncture combined with endovascular route

OBJECTIVE

To report our experience to embolize the AVM of jaws by direct puncture in conjunction with endovascular treatment.

METHODS

5 cases of AVM of mandible and 2 cases of AVM of maxilla comprised this study group. The patients were embolized with coils with wool strands and PVA. The coils were placed directly into the center of the intraosseous lesion. The procedure was under the guidance of DSA machine (PHILIPS V3000).

RESULTS

The acute arterial bleeding of 4 patients was controllable. The chronic oozing bleeding in the other 3 cases disappeared in the 3 - 24 months follow-up and new bone formation was found in the follow-up radiography.

CONCLUSIONS

The embolization of the AVM of jaws by direct puncture in conjunction with endovascular therapy is effective and safe, however the longer follow-up is expected.

Experimental and comparative study of the blood supply to the mandibular cortex in Göttingen minipigs and in man

INTRODUCTION

Since the blood supply to the mandibular cortex is an important factor for bone growth and bone repair, experimental studies on the blood supply in animal models (such as Göttingen minipigs) applicable to man are necessary. Their value depends on the requirement that the patterns of blood supply in the two species are similar.

MATERIAL AND METHODS

Twelve Göttingen minipig mandibles (24 halves) and four human mandibles (eight halves) were investigated for the blood supply to the mandibular cortex.

RESULTS

Only minor differences were found in blood supply to the mandibular cortex between the two species. Common to both was: in the cranial part of the mandible (including the condyle), the endosteal blood supply prevailed, whereas the periosteal blood supply predominated in the caudal part of the mandible (the body). Both patterns of blood supply were in balance in the centre section, i.e. angle and ascending ramus of the mandible.

CONCLUSION

The present study confirms that results obtained from Göttingen minipigs, used as an experimental animal model, are applicable to man: three different types of blood supply are evident in the mandibular cortex in both species.

Direct-puncture embolization of intraosseous arteriovenous malformation of jaws

PURPOSE

Our goal was to report our experience with direct-puncture embolization of intraosseous arteriovenous malformations (AVMs).

PATIENTS AND METHODS

Three cases of AVM in the mandible and 2 cases of AVM in the maxilla comprised this study group. The patients were embolized with fiber coils through direct puncture, and the coils were placed directly into the center of the intraosseous lesion, in some cases in conjunction with polyvinyl alcohol foam and N-butyl-2-cyanoacrylate through vascular access.

RESULTS

The acute arterial bleeding was controllable in 3 patients. The other 2 patients had pericoronal oozing bleeding and a warm soft pulsative mass on the left face, respectively; their symptoms and signs improved greatly. The pericoronal oozing of blood in all patients disappeared during a 3- to 13-month follow-up, and new bone formation was found on the follow-up radiography.

CONCLUSIONS

The embolization of the AVM of jaws by direct percutaneous puncture in conjunction with endovascular therapy is effective and safe, but longer follow-up is required to determine the true efficacy of this method of treatment.

Effects of selenium on the structure of the mandible in experimental diabetics

In the treatment of diabetes-induced pathologies, beneficial results have been obtained with administration of antioxidants. Selenium is an antioxidant and essential trace element in living organisms. The aim of this study was to investigate the possible effects of selenium on the structural alterations of the mandible due to diabetes. In this study thirty-nine Wistar rats were used and a control, a selenium given control, a diabetic and a selenium given diabetes groups were formed. Experimental diabetes was induced by a single i.p. injection (50 mg/kg) of streptozotocin (STZ). The diabetic + selenium and the control + selenium groups were injected with a daily dose of 5 micro mol/kg/day sodium selenite (i.p.) for 4 weeks while the diabetic and the control groups were injected with distilled water. Mandibles of all the animals were excised and examined at the 5th week. High blood glucose level and low body weight in the diabetic group were not significantly affected by selenium administration. Furthermore, a negligible increase in blood glucose level was observed in the selenium given control group. Densitometric analysis revealed a significant reduction in bone density and presence of resorption in the diabetic and the selenium given control groups as compared to the selenium given diabetes and the control groups. In X-ray diffraction analysis, the reduction in peak intensity of the reflected light in both the diabetic and the selenium given control groups indicated a possible alteration in the crystallinity or a poor crystalline substance. Histological investigation showed that there was progressive resorption, trabecular and cortical irregularity and vascular proliferation in the diabetic and the selenium given control groups, whereas a more healthy appearance was detected in the selenium given diabetes group. The results of this study suggest the positive effects of selenium on diabetes-induced structural alterations in the mandible. However, the unexpected results in the selenium given control group necessitate further studies on the mechanism of selenium effects in organisms.

[Changes in the inferior alveolar vessels and angiogenesis following mandibular lengthening with different rates of distraction]

OBJECTIVE

The purpose of this study was to study the changes in the inferior alveolar vessels and angiogenesis following mandibular lengthening with different rates of distraction.

METHODS

Bilateral mandibular corticotomies were performed in 6 goats. The mandibles in 6 goats were lengthened 10.0 mm using a custom-made distractor with different rates of distraction (1.0 mm/d[n = 3] and 2.0 mm/d [n = 3]); the other 2 nondistracted mandibles served as control. The goats with distracted mandibles were killed at 2 weeks after completion of distraction. The inferior alveolar vessels with distracted calluses were harvested and processed for histologic and morphometric evaluation.

RESULTS

No pathological changes in the inferior alveolar vessels were found following mandibular osteodistraction. However, the number of microvessels within distraction gap in the animals distracted at a rate of 1.0 mm/day was greater than that in the goats distracted using a rate of 2.0 mm/day, and more mature newly formed bone trabeculae was observed.

CONCLUSION

There were no significant changes in the inferior alveolar vessels after mandibular lengthening with distraction osteogenesis, but rapid distraction may have adverse effects on the aniogenesis in the distraction gap.

[Evaluating angiogenesis and osteogenesis modified by vascular endothelial growth factor (VEGF)]

PURPOSE

This intention of this study was to investigate the influence of controlled release of vascular endothelial growth factor (VEGF) on angiogenesis and osteogenesis in a mandibular defect model.

METHODS

A total of 56 rabbits were operated and bicortical holes were placed in the mandible. The defects were filled with collagen type I implants, collagen implants complexed with 0.8-microgram VEGF165, or left without any filling. After 3, 7, 14, and 28 days specimens were taken and histologic, histomorphometric, and immunohistologic analyses were carried out concerning density of vessels, total surface of vessels, bone surface, and bone density.

RESULTS

The number of vessels was increased in all groups up to 14 days, followed by physiologic regression in the control groups, whereas the study group showed persistently high numbers. The density of regenerated bone was significantly higher in the study group.

CONCLUSION

The activation of angiogenesis using VEGF165 leads to more intensive angiogenesis and bone regeneration.

Changes of blood flow in the mucosa underlying a mandibular denture following pressure assumed as a result of light clenching

The aim of this study was to investigate the influence of the continuous compression assumed as a result of light clenching on the blood flow of the denture underlying mucosa in tissue-supported or tooth-tissue-supported denture wearers. Measurements were carried out on eight removable partial denture wearers (three males and five females, from 50 to 72 years, mean age: 61.5 years). The blood flow in the denture underlying mucosa was measured at the unilateral mandibular first molar region using an experimental denture base equipped with a laser Doppler flowmeter. The area of the experimental denture base was 2 cm2, and the loading force was 1 kgf. The loading time was set at 5, 10, 20, 30 and 60 s. The blood flow after 20 s loading was <15% in rest. The times from release of loading to the maximum blood flow and from release of loading to recovery up to 110% of the blood flow at pre-loading were significantly prolonged by an increase in the loading time. Even if it is light, a continuous clenching results in ischaemia and delays the recovery of blood flow in the mucosa underlying the denture after release of compression.

Early revascularization of membranous inlay bone graft in canine mandible model

The early revascularization of a membranous inlay bone graft in a canine mandible was investigated using bone scans and histological examinations. Eight 5-month-old mongrel dogs were used as the subjects. The inlay bone graft, a 1- x 2-cm critically sized bone, was completely separated from the lower border of the canine mandible and then refixed to the original site. Bone scans and histological examinations were performed in the first, second, third, and fourth postoperative weeks. The bone scan in the first postoperative week revealed radioisotope uptake on the margin of the grafted bone with an isotope count that was 21% of the normal bone uptake. In the second postoperative week, the radioisotope uptake in the grafted bone increased to 52% of the normal bone uptake. In the third and fourth postoperative weeks, the isotope uptakes were 111% and 124%, respectively. The histological findings in the first postoperative week showed an absence of osteoblastic activity and 6 viable blood vessels in a field magnified x 200, which was the equivalent of 25% of the vessels of the normal bone. In the second postoperative week, osteoblastic activity was noted, and the number of viable blood vessels increased to 15, that is, 63% of the vessels of the normal bone. In the third postoperative week, there was an increase in osteoblastic activity, and the number of viable blood vessels was 21, that is, 88% of the vessels of the normal bone. In the fourth postoperative week, there was a marked increase in osteoblastic activity with the number of vessels reaching 23, that is, 96% of the normal bone. In summary, revascularization of the membranous inlay bone graft began within the first week after the bone graft and thereafter gradually increased. In the third postoperative week, revascularization returned to a near-normal value compared with the value of the adjacent normal mandibular bone.

Haematoma of the floor of the mouth following implant placement

Placement of implants in the anterior mandibular region is generally regarded as a routine, safe procedure. This case report describes an extensive haematoma in the floor of the mouth, following such a procedure, which rapidly became life-threatening, requiring an emergency tracheostomy to establish a surgical airway. The anatomic, radiographic and surgical aspects to the problem are discussed. Finally, when undertaking such procedures it is advisable to perform them reasonably close to a hospital where such a complication can be effectively and promptly handled by suitably trained persons.

Blood supply of the mandibular cortex: an experimental study in Göttingen minipigs with special reference to the condyle

INTRODUCTION

Blood supply of the mandible is an important factor that influences bone growth and bone repair.

MATERIAL AND METHODS

An experimental study was carried out in 24 mandibles of 12 Göttingen minipigs to study the blood supply of the mandibular cortex.

RESULTS

Endosteal blood supply prevails in the cranial part of the mandible including the condyle, whilst periosteal blood supply predominates in the caudal part of the mandible, the body. The two forms of blood supply are in balance in the ascending ramus and the angle of the mandible.

CONCLUSION

The mandibular cortex can be divided into three parts, each having different sources of blood supply. The results of this study may be of significance for man and could help to understand some pathological disorders of the mandible.

Immunolocalization of osteoclast differentiation factor in rat periodontium

The aim here was to observe the immunohistochemical localization of osteoclast differentiation factor (ODF)/receptor activator of NF kappa B ligand (RANKL) in the rat periodontium. Rat mandibles were demineralized and embedded in paraffin, and horizontal and frontal sections were prepared for immunohistochemical analysis. In horizontal sections, immunolocalization of RANKL was marked in the distal area of the periodontium of molars in which osteoclasts appeared, due to physiological tooth drift. In frontal sections, RANKL immunoreactivity was localized on spindle-shaped mesenchymal cells around blood vessels near the bone surface in the periodontium. In addition, immunoreaction for RANKL was detected on structures that appeared to be elongated cell processes near blood vessels in frontal sections. Immunohistochemical examination for the general antigen of nerve-specific protein suggested a similarity between these structures and nerve fibres.

Arteriovenous malformation of the mandible: review of literature and case history

Vascular malformations of the jaws can lead to disastrous complications, but there seems to be no consensus as to their treatment. The literature presents the pathophysiology and clinical aspects of these lesions, as well as the divergent views of the authors. Treatment by catheterization and embolization, with direct transosseous injection of cyanoacrylate, appears to be the least harmful and most permanent treatment in certain conditions, as evidenced by the case of this 9-year-old patient having a high-flow mandibular vascular malformation