Conservative treatment of arteriovenous malformations of the mandible

A modified technique is reported on the treatment of arteriovenous malformations in the mandibular body. The technique consists of highly selected embolization and piecemeal removal of the lesion through burred holes made in the cortex. This way the mandible and the teeth may be saved in selected patients.

Arteriovenous malformation of the mandible: embolization and direct injection therapy

Arteriovenous malformation (AVM) of the mandible is a rare entity but one that can be potentially fatal as a result of massive hemorrhage. Traditional treatment involved extensive surgical resection of the mandible. With the advent of improved endovascular techniques, interventional radiology is now the best method to control active hemorrhage and ultimately cure these lesions. The authors describe three cases of successfully treated mandibular AVM by percutaneous and/or endovascular techniques.

Existence of alpha(1A)- and alpha(1B)-adrenoceptor subtypes in canine mandibular alveolar arteries

1. The present study attempted to pharmacologically characterize the alpha-adrenoceptor subtypes mediating vasoconstriction in canine isolated and perfused mandibular alveolar artery (MAA). 2. Noradrenaline (NA) and phenylephrine (PE) induced a strong vasoconstriction in a dose-dependent manner. The PE-induced vascular constriction was significantly inhibited by treatment with prazosin. Xylazine evoked a moderate vascular constriction and the xylazine-induced response was suppressed by rauwolscine. The NA-induced response was partially inhibited by rauwolscine and the remaining response to NA was abolished by subsequent administration of prazosin. 3. Treatment of MAA with WB4101 produced a dose-dependent inhibition of NA-induced vasoconstriction. Pretreatment of tissues with 10 micromol/L chloroethylclonidine produced a slight and statistically significant inhibition of NA-induced responses. BMY 7378, a selective alpha(1D)-adrenoceptor antagonist, failed to significantly affect vasoconstrictor responses to NA. 4. The present results suggests that: (i) both alpha(1)- and alpha(2)-adrenoceptors are involved in vasoconstrictor responses in the canine MAA; and (ii) the alpha(1)-adrenoceptors involved in the vasoconstrictor responses in the MAA are characterized as mainly of the alpha(1A)- and partially of the alpha(1B)-adrenoceptor subtype.

3D-CT vascular setting protocol using computer graphics for the evaluation of maxillofacial lesions

In this paper we present the aspect of a mandibular giant cell granuloma in spiral computed tomography-based three-dimensional (3D-CT) reconstructed images using computer graphics, and demonstrate the importance of the vascular protocol in permitting better diagnosis, visualization and determination of the dimensions of the lesion. We analyzed 21 patients with maxillofacial lesions of neoplastic and proliferative origins. Two oral and maxillofacial radiologists analyzed the images. The usefulness of interactive 3D images reconstructed by means of computer graphics, especially using a vascular setting protocol for qualitative and quantitative analyses for the diagnosis, determination of the extent of lesions, treatment planning and follow-up, was demonstrated. The technique is an important adjunct to the evaluation of lesions in relation to axial CT slices and 3D-CT bone images.

Lingual vascular canals of the mandible: evaluation with dental CT

PURPOSE

To evaluate whether dental computed tomography (CT) can depict the frequency, diameter, position, and direction of vessels entering the mandible through lingual bone canals.

MATERIALS AND METHODS

Thirty-two consecutive patients underwent preimplantation CT of the lower jaw and examination for the presence, number, location, diameter, and direction of lingual canals entering the mandible. In addition, three cadaver mandibles were investigated with dental CT and subsequently dissected to confirm the CT findings.

RESULTS

All patients demonstrated at least one lingual vascular canal, and 20 (63%) had multiple (two to five) canals. The typical lingual canal locations were the midline of the mandible and the premolar region. The mean diameter of the lingual canals was 0.7 mm +/- 0.3 (SD) (range, 0.4--1.5 mm) in the midline and 0.6 mm +/- 0.2 (range, 0.3--1.2 mm) in both premolar regions of the mandible. Examination results in the three cadaver mandibles confirmed the CT findings in those mandibles.

CONCLUSION

Dental CT can depict the occurrence, position, and size of the lingual vascular canals of the mandible. Radiologists should be aware of this anatomic feature and its possible implications.

Nutrient arteries of the temporomandibular joint: an anatomical and a pathological study

We have identified an artery which is a sub-branch of the inferior alveolar artery, and propose to call it the temporomandibular branch. Mandibular bones of 36 autopsy cases (ages 23-85; 20 males and 16 females) were examined. Contrast media were injected into the inferior alveolar artery, decalcification was conducted, and photographs were taken using soft X-ray equipment (Softex: Nippon Softex, co. CSM type). Then, an examination was conducted concerning sclerosis of these arteries. Next, H.E., Azan, and Pap silver stains were used for microscopic specimens to examine arteriosclerosis of the temporomandibular joint. The artery that sub-branches toward the temporomandibular branch, branches out immediately after the inferior alveolar artery and enters the mandibular foramen, becoming the artery that supplies the temporomandibular joint. This temporomandibular branch travels slightly downward, forward of the inferior alveolar artery, and turns back toward the mandibular base. It advances to the mandibular joint almost directly. The route taken was classified into three types. Toward the head of the mandible, the temporomandibular branch, after passing over the neck of the mandible, divides into two sub-branches, anterior and posterior. In our pathological study of the temporomandibular branch, there were a small number of cases with slight intimal thickening and mild elastosis. As regards sclerotic changes, particularly in cases more than 50 years old. There were very few cases showing intimal changes. Sclerotic changes of the artery supplying the head of the mandible increase with age. The same can be said of the about the constriction rate. These findings correlated with subject age.

Preoperative determination of the location of parotid gland tumors by analysis of the position of the facial nerve

PURPOSE

This study examined the usefulness of anatomic lines in predicting the intraparotid course of the facial nerve.

MATERIALS AND METHODS

To make the comparison, 3 lines were drawn on 69 transverse sections of 5 cadaver heads. Then, the shortest and the longest distance from the lines to the facial nerve were measured.

RESULTS

Of the tested lines, the one that connects the most dorsal point on the ipsilateral half of a vertebra to the dorsal side of the retromandibular vein had the shortest distance to the facial nerve. It also ran more parallel to the facial nerve than the other 2 lines.

CONCLUSIONS

Because the line that connects the most dorsal point on the ipsilateral half of a vertebra to the dorsal side of the retromandibular vein best predicts the intraparotid course of the facial nerve, it might be useful in assessing whether parotid tumors are located in the superficial or deep lobe.

Assessment of the incorporation of revascularized fibula grafts used for mandibular reconstruction with F-18-PET

AIM

Determination of the range of regional blood flow and fluoride influx during normal incorporation of revascularized fibula grafts used for mandibular reconstruction. Evaluation, if healing complications are preceded by typical deviations of these parameters from the normal range. Assessment of the potential influence of using "scaled population-derived" instead of "individually measured" input functions in quantitative analysis.

METHODS

Dynamic F-18-PET images and arterialized venous blood samples were obtained in 11 patients early and late after surgery. Based on kinetic modeling regional blood flow (K1) and fluoride influx (Kmlf) were determined.

RESULTS

In uncomplicated cases, early postoperative graft K1--but not Kmlf--exceeded that of vertebrae as reference region. Kmlf values obtained in graft necrosis (n = 2) were below the ranges of values observed in uncomplicated healing (0.0113-0.0745 ml/min/ml) as well as that of the reference region (0.0154-0.0748). Kmlf values in mobile non-union were in the lower range--and those in rigid non-union in the upper range of values obtained in stable union (0.0211-0.0694). If scaled population-derived instead of measured input functions were used for quantification, mean deviations of 23 +/- 17% in K1 and 12 +/- 16% in Kmlf were observed.

CONCLUSIONS

Normal healing of predominantly cortical bone transplants is characterized by relatively low osteoblastic activity together with increased perfusion. It may be anticipated that transplant necrosis can be identified by showing markedly reduced F- influx. In case that measured input functions are not available, quantification with scaled population-derived input functions is appropriate if expected differences in quantitative parameters exceed 70%.

Rat mandibular distraction osteogenesis: latency, rate, and rhythm determine the adaptive response

Distraction osteogenesis is a well-established technique of endogenous tissue engineering. The biomechanical factors thought to affect the quality of the distraction regenerate include the latency, rate, rhythm, and consolidation period. In an effort to understand the impact of these parameters on regenerate bone formation, this study was designed to decipher the most adaptive response in a rat model of mandibular distraction osteogenesis. Ninety-six adult Sprague-Dawley rats were divided into 16 subgroups (n = 6 per subgroup) based on variations in the distraction parameters (i.e., latency, rate, and rhythm). After a 28-day consolidation period, the mandibles were harvested, decalcified, and sectioned. A standardized histologic ranking system was used to evaluate the effect of each protocol on the adaptive response of the regenerate bone. In this study, we have demonstrated that the latency period dramatically affects the success of distraction osteogenesis. Furthermore, distraction rates up to 0.50 mm per day stimulated excellent regenerate bone formation, whereas greater distraction rates produced a fibrous union. Finally, higher frequency distraction (i.e., increased rhythm) appeared to accelerate regenerate bone formation. We believe that defining the critical parameters of this model will improve future analysis of gene expression during rat mandibular distraction osteogenesis and may facilitate the development of biologically based strategies designed to enhance regenerate bone formation.

Detection of the mandibular canal via shaded surface display and multiplanar reconstruction of CT data

The purpose of this study was to evaluate the sensitivity of conventional two-dimensional (2D) multisection images (multiplanar rendering, MPR) and registered three-dimensional (3D) shaded surface images (shaded surface display, SSD) of standard axial computed tomography (CT) data for detecting the mandibular canal (MC) in the lower jaw of 136 patients. The patients, who had different indications for mandibular CT, were examined using standard axial CT scanning. Two post-processing programs were used for 3D visualization of the data sets. The cross-sectional rendered images and the shaded surface 3D images were graded for detection of the MC, the presence of artefacts, overall quality and clinical relevance. A 3D display of the MC was achieved using the MPR technique in 100% with high image quality. The surface rendered display depicted the MC in 80%. Artefacts markedly degraded the 3D displays obtained using the surface rendering technique; thus, SSD is an inappropriate technique for imaging the entire MC without manual segmentation. MPR-CT improves the sensitivity of CT imaging in the detection of the MC with very little time needed for post-processing compared with the SSD method. This post-processing modality should, therefore, be considered for serial studies of patients undergoing dental CT. The sensitivity of the MPR method is even superior to the standard axial CT slices.

Continuous radiographic visualization of the mandibular nutrient canals

The continuous radiographic appearance of the course of mandibular nutrient canals (NC), originating from the incisive branch of the inferior alveolar neurovascular bundle bilaterally, showing anastomoses and terminating in the interdental area of the anterior teeth, is reported for the first time.

Endovascular management of a bleeding mandibular arteriovenous malformation by transfemoral venous embolization with NBCA

A 13-year-old boy presented with an arteriovenous malformation (AVM) involving the left mandible that bled after intraoral biopsy. The AVM was treated on an emergency basis by primary intravenous delivery of n-butyl cyanoacrylate after transfemoral catheterization, resulting in complete anatomic and clinical cure.

Computed tomographic diagnosis and localization of bone canals in the mandibular interforaminal region for prevention of bleeding complications during implant surgery

In this study, computed tomograms (CTs) of 70 patients were examined for visible vascular canals in the mandible as well as for their localization, incidence, diameter, and content. All patients examined showed at least 1 lingual perforating bone canal in the mandible. Since such vascular canals are encountered regularly, routine CT examination is recommended prior to implant surgery to help avoid severe bleeding complications during the placement of implants in the interforaminal region.

Histomorphometric analysis of age changes in the human inferior alveolar artery

Angiography is often used to investigate age-related changes in the inferior alveolar artery, the major nutrient artery of the mandible. Although histological examinations have been made from several viewpoints, e.g. age change, pathogenesis of osteoradionecrosis, and relation to tooth extraction, these studies have used a limited number of samples and simple histometric methods. The purpose here was to describe histopathological and histomorphometric age-related changes, and to investigate the relation between dentate status and the histomorphometry of the artery. Inferior alveolar arteries from 162 autopsy cases (age range 3-86 years) were examined histometrically with a mathematically standardized method. Histologically, there was diffuse fibrous intimal thickening, but no atheroma formation. Histometric analyses revealed a very gradual increase in both the radius of the artery and the thickness of the media with age, but the luminal radius did not correlate with age. Intimal thickness increased exponentially with age with very different features from those of the increase in the media. The relative radius of the lumen decreased with age after the sixth decade; this is thought to be an index for senile changes in the artery. Among the variables of arterial architecture examined, no particular difference was found between the dentate and non-dentate cases in the molar region.

Emergency tracheostomy following life-threatening hemorrhage in the floor of the mouth during immediate implant placement in the mandibular canine region

BACKGROUND

The edentulous interforaminal mandibular area is frequently the preferred area for implant placement.

METHODS

A case of emergency tracheostomy following life-threatening hemorrhage in the floor of the mouth during immediate implant placement in the mandibular canine region is described. The probable cause was bleeding from the sublingual artery or a branch of that artery following implant perforation of the lingual cortex.

RESULTS

Healing was uneventful and the patient was released from the hospital after 11 days. Three years later, CT showed a well-osseointegrated implant with a severe buccolingual inclination.

CONCLUSIONS

It is stressed that short implants (14 mm or less) should be used in the mandibular canine region and that effective treatment of this complication is essential.

Color Doppler flow imaging of the facial artery and vein

The purpose of this study was to provide some guidelines with respect to the location of the facial vessels, display the potential inverted blood flow of the facial artery, and reemphasize the value of color Doppler ultrasound studies in flap planning. An anatomic study of the facial artery and vein was done using color Doppler ultrasonography in 12 adults. The artery and the vein were located together at the lower border of the mandible. Around the oral commissure and under the nasal ala, they were located apart from each other with variable distances. This divergence of the facial vein from the artery is important information in the planning of axial pattern flaps. Furthermore, the reverse flow was observed in 12 patients after the blood flow of the facial artery was stopped by applying pressure manually at the lower border of the mandible. Observation of the reversed flow confirms the possibility of safe elevation of a retrograde flow-arterialized flap based on the distal portion of the facial artery.

Surgical technique for the treatment of high-flow arteriovenous malformations of the mandible

The high-flow intraosseous arteriovenous malformation is a problematic vascular lesion which may affect bone and the dentition. Variable clinical presentations of this anomaly have resulted in a gamut of treatment modalities being reported ranging from simple curettage, resection, radiotherapy, sclerosing injections, and various forms of embolization, to immediate replantation of the resected segments. Embolization techniques alone have not been universally successful and have often resulted in rapid development of collaterals from surrounding vessels. Definitive treatment has usually involved complete surgical resection (when feasible) either alone, or in combination with other modalities such as embolization. Jaw resection, however, is deforming and leaves a defect often requiring subsequent reconstruction of the hard and soft tissues and replacement of any teeth lost with the resected segment. We report a surgical technique to treat mandibular arteriovenous malformations, which permits ligation of the feeding vessels and provides access allowing for complete removal of the intraosseous lesion. At the same time it not only prevents facial deformity by preserving the mandibular bone and oral soft tissue, but also, and more importantly, may preserve the dentition as well.

Doppler sonography for the assessment of central mandibular blood flow

In this study we evaluated the role of Doppler sonography in the assessment of central mandibular blood flow. We assessed the characteristics of blood flow in the mental artery, the larger terminal branch of the inferior alveolar artery, in 30 healthy volunteers equally distributed in the age groups 20-39, 40-59 and over 60 years. We used a DWL Multi-Dop X4(R) Doppler sonography machine (DWL GmbH) with an 8 MHz probe applied intraorally. The variables analysed were patency, time averaged maximum velocity (TAMV), pulsatility index (PI), discomfort and the duration of the procedure. All the arteries analysed were patent. The TAMV and PI decreased as age increased and there were significant differences between the age groups: TAMV (P = 0.01), PI (P = 0.006). Pair-wise comparisons also showed significant differences (P< 0.05) between the 20-39 and the over 60 age group, 40-59 and the over 60 age group for TAMV, and between the 20-39 and over 60 age group for PI. The difference in measurements between the right and left sides in individual patients was not significant. The assessment took about 20 minutes and caused little discomfort. The technique is simple and could potentially be used to influence clinical decisions.

Monitoring of graft perfusion and osteoblast activity in revascularised fibula segments using [18F]-positron emission tomography

The aim of the present study was to evaluate healing of revascularised fibula grafts used for mandibular reconstruction using [18F]fluoride ion and positron emission tomography (PET). Sixteen PET studies in 11 fibula grafts were analysed to determine both blood flow and fluoride influx as a measure of vascularisation and osteogenic activity. Two graft failures and three non-unions were encountered and were compared to the successfully healed grafts. In uneventful graft healing, early PET studies (on average 19 days after grafting) showed a significantly increased blood flow to the grafted bone and to the union between the grafts and the mandibles when compared to the reference region of the cervical spine. In contrast, fluoride influx was significantly lower in the grafts when compared to the plating area and the cervical spine. Six months after grafting, blood flow to the grafted bone and the mandibular bone had returned to a level comparable with the reference region. Fluoride influx remained significantly lower in the grafts than in the plating areas or cervical spines. Graft failures were associated with negligible fluoride influx near zero in early PET studies. These results suggest that revascularised fibula grafts provide a low osteogenic potential, presumably due to the pre-existing lack of cancellous bone. The relatively high frequency of non-unions makes meticulous adaptation of the graft and the mandible mandatory, particularly in patients with compromised viability of the recipient bone.