Anatomic variations of the superficial temporal artery.

The superficial temporal artery (STA) is a terminal branch of the external carotid artery. It is commonly described as coursing posterior to the mandibular condyle and over the posterior zygomatic root (PZR) and then dividing terminally into parietal and frontal branches. However, possible variations of the main trunk of the STA have seemingly been overlooked. This study retrospectively examined the archived head tomography angiograms of 43 patients to determine the morphology and topography of the STA prior to its terminal bifurcation. In 79% of patients, the STA topography related to the mandibular condyle was bilaterally symmetrical, either retrocondylar (65.1%) or laterocondylar (13.6%). The parietal branch was sometimes absent unilaterally (16.3%) or bilaterally (9.3%). In 2/43 cases, the frontal branch of the STA was unilaterally absent. When both terminal branches were present, the bifurcation was retrocondylar or immediately above the PZR when on the PZR, or the terminal division of the STA was high above the PZR. In 88.4% of the STAs, different patterns of kinking and coiling were documented, including retrocondylar kinks (27.9%), laterocondylar kinks (20.9%), kinks placed on the PZR (81.4%) and variably oriented suprazygomatic kinks (32.6%). Five of the 86 STAs were coiled, one retrocondylar, one laterocondylar, and three other placed on the PZR. Two cases showed unilateral pseudoaneurysms of the STA, one above the PZR and the other on the temporomandibular joint. The STA is surgically important; therefore, the number of anatomical studies of the STA should increase.

The Effect of Platelet-Rich Plasma on the Temporomandibular Joint After Radiotherapy in Rabbits.

OBJECTIVES: Platelet-rich plasma (PRP) was administered into the temporomandibular joint (TMJ) space, which had been exposed to radiotherapy (RT), in an attempt to prevent and/or treat the late-term complications associated with RT when used for the treatment of head and neck cancers (nasopharyngeal cancer in particular) on the musculoskeletal system. METHODS: A total of 13 adult male New Zealand ( Oryctolagus cuniculus) rabbits were used in the study. The animals were classified into 3 groups: 6 in the RT group, 6 in the RT+PRP group, and 1 in the control group (exposed to neither). The TMJ space of each rabbit was exposed to 2240 cGy external RT in total, and PRP was administered into the TMJ space 1 month later. The joints were surgically removed 1 month later and examined histopathologically. RESULTS: In the group given RT+PRP, the level of inflammation, amount of muscle fibrosis, vascular wall fibrosis, synovial membrane and condyle cartilage thickness, temporal extrabone fibrous cell layer count, and intramuscular changes were similar to those recorded in the control group, although the positive effects of PRP were not found to be statistically significant. CONCLUSIONS: The findings of the present study demonstrate that injections of PRP may increase joint inflammation and therefore enhance blood supply, resulting in the onset of regeneration. These favorable effects of PRP may be helpful in the fight against late-term musculoskeletal complications of RT and may minimize such side effects as sore jaw, malnutrition, and weight loss.

Arterial Vascularization of the Mandibular Condyle and Fractures of the Condyle.

BACKGROUND: Despite substantial displacements, fractures of the mandibular condyle rarely lead to necrosis. This illustrates the negligible role of the inferior alveolar artery in intraosseous supply to the condyle, and led to this systematization of its arterial vascularization. METHODS: Forty-two temporomandibular joints from nonembalmed cadaveric specimens were studied following injection of latex (n = 32) or India ink (n = 10). RESULTS: The intraosseous branches of the inferior alveolar artery that lead to the condyle were inconstant and often rudimentary. In this study, the arteries that consistently led to the condyle were the superficial temporal artery, the deep posterior temporal artery, and arterial branches leading to the lateral pterygoid muscle emanating directly from the maxillary artery. These arteries, along with the transverse facial artery and the masseteric artery (when they participated in condoyle vascularization), formed a quadrangle around the mandibular condyle. After India ink injection, the pterygoid muscle was the most strongly colored muscle, thus indicating substantial vascularization. CONCLUSIONS: Although there is a lack of consensus in the literature regarding the constancy and proportions of the arteries participating in vascularization of the condyle, the superficial temporal artery, the maxillary arterial branches leading to the lateral pterygoid muscle, and the deep posterior temporal artery were constant in this study. This study shows the important role of the lateral pterygoid in the vascularization of the condyle. In case of a fracture with substantial displacement, the vascularization emanating from the superficial temporal artery and the lower alveolar artery is ruptured or compromised.

HMGB1-induced angiogenesis in perforated disc cells of human temporomandibular joint.

High mobility group 1 protein (HMGB1), a highly conserved nuclear DNA-binding protein and inflammatory mediator, has been recently found to be involved in angiogenesis. Our previous study has demonstrated the elevation of HMGB1 in the tissue of perforated disc of temporomandibular joint (TMJ). Here, we investigated a novel mediator of HMGB1 in regulating hypoxia-inducible factor-1α (HIF-1α) and vascular endothelial growth factor (VEGF) to mediate angiogenesis in perforated disc cells of TMJ. HMGB1 increased the expression of HIF-1α and VEGF in a dose- and time-dependent manner in these cells. Moreover, immunofluorescence assay exhibits that the HIF-1α were activated by HMGB1. In addition, HMGB1 activated extracellular signal-related kinase 1/2 (Erk1/2), Jun N-terminal kinase (JNK), but not P38 in these cells. Furthermore, both U0126 (ErK inhibitor) and SP600125 (JNK inhibitor) significantly suppressed the enhanced production of HIF-1α and VEGF induced by HMGB1. Tube formation of human umbilical vein endothelial cells (HUVECs) was significantly increased by exposure to conditioned medium derived from HMGB1-stimulated perforated disc cells, while attenuated with pre-treatment of inhibitors for VEGF, HIF-1α, Erk and JNK, individually. Therefore, abundance of HMGB1 mediates activation of HIF-1α in disc cells via Erk and JNK pathway and then, initiates VEGF secretion, thereby leading to disc angiogenesis and accelerating degenerative change of the perforated disc.

Benefits of using the ultrasonic BoneScalpel™ in temporomandibular joint reconstruction.

PURPOSE: The main objective of this retrospective study is to analyze and report on our operative experiences and outcomes using the ultrasonic BoneScalpel™ (BoneScalpel) versus a conventional reciprocating saw (RecipSaw) for the purpose of completing the osteotomies in total temporomandibular joint reconstruction (TJR) surgery. MATERIALS AND METHODS: 23 consecutive patients presented with a diagnosis of either degenerative joint disease (n = 23), a failing autogenous TJR (n = 1), heterotrophic bone formation (n = 1) or a subcondylar fracture (n = 1) for a total of 26 joints that received a TJR. 13 unique TJR surgeries employed the use of the BoneScalpel to perform the osteotomies and 13 used the RecipSaw. RESULTS: There was a 49% reduction in the average volume of blood loss in the BoneScalpel group compared to the RecipSaw group (130cc vs. 268cc, p ≤ 0.004), unpaired t-test). For the other variables it was observed that there were more favorable clinical results using the BoneScalpel but without statistically significant differences given the small sample size relative to the prevalence of the outcome that was being measured. CONCLUSIONS: Use of the BoneScalpel in TMJ reconstruction is overall safer and results in less blood loss compared to surgeries employing the use of the conventional RecipSaw for completing osteotomies.

Irrigación e inervación de la articulación temporomandibular: una revisión de la literatura / Irrigation and innervation of the temporomandibular joint: a literature review

El conocimiento de los nervios aferentes, de la irrigación vascular y del drenaje venoso comprometido en la articulación temporomandibular es relevante para entender la fisiología del sistema estomatognático. El objetivo de este estudio fue identificar los vasos sanguíneos y los nervios involucrados en la irrigación e inervación de la ATM, y si los términos utilizados en la literatura científica respetan lo establecido en Terminología Anatomica Internacional (TAI).Se realizó una revisión de la literatura en la que se incluyeron 10 libros y 11 artículos científicos. La mayoría de los autores señalaron que la irrigación de la ATM se lleva a cabo por ramas de la arteria temporal superficial y ramas de la arteria maxilar, que a su vez son ramas de la arteria carótida externa. El drenaje venoso estaría dado por las venas temporales superficiales y por el plexo pterigoideo. La inervación sensitiva provenía del nervio mandibular, ramo del V par craneal y sus ramos auriculotemporal, maseterino y los nervios temporales profundos. Los autores concuerdan en los principales vasos y ramos nerviosos que dan irrigación e inervación a la ATM, aunque también se mencionan otros vasos y nervios menos descritos. El drenaje venoso de la ATM se encuentra escasamente descrito en la literatura.

The knowledge of the afferent nerves, vascular supply and venous drainage of the temporomandibular joint is relevant to understand the physiology of the stomatognathic system. The aim of this study was to identify the blood vessels and nerves involved in the blood supply and innervation of the TMJ, and if the terms used in the scientific literature respects the Terminologia Anatomica. Ten books and 11 scientific articles were included. A literature review was conducted. Most authors suggest that TMJ irrigation is carried out by branches of the superficial temporal artery and branches of the maxillary artery, which are branches of the external carotid artery. The venous drainage would be given by the superficial temporal vein and by the pterygoid plexus. The sensory innervation was given by the mandibular nerve, branch of the V cranial nerve and its branches auriculotemporal, masseteric and the deep temporal nerves. The authors agree on the major vessels and nerve branches that provide irrigation and innervation to the TMJ, although other less described vessels and nerves are also mentioned. The venous drainage of the TMJ is poorly described in the literature.

Morphological Study of the Articular Disc and Capillary of the Retrodiscal Tissue in a Type 2 Spontaneous Diabetes Mellitus Rat Model.

The objective of this study was to evaluate morphological changes at the articular disc of the temporomandibular joint and capillary of the retrodiscal tissue in a rat model for type 2 spontaneous diabetes mellitus (DM) (i.e., Goto-Kakizaki [GK] rats) compared to normal Wistar rats. A total of 20 experimental rats were used in this study; the rats were categorized into the normal (n = 10 male 8-week-old Wistar rats) and DM (n = 10 male 8-week-old GK rats) groups. Hematoxylin-eosin stained specimens were obtained from 5 rats from each group. Image analyses of the hematoxylin-eosin stained specimens were conducted using light micrographs, which allowed comparisons of the thickness of the anterior, central, and posterior parts of the articular disc. Afterwards, the microvascular corrosion cast specimens were obtained from 5 rats from each group. The diameter of the capillary of the retrodiscal tissue was determined by analyzing scanning electron micrographs of the microvascular corrosion cast specimens. Student's t-test was used to test for statistical significant differences between the 2 groups. Differences were considered significant when p < 0.01. We found that the thickness of the anterior, central, and posterior parts of the articular disc, and the diameter of the capillary of the retrodiscal tissue was significantly lower in the DM vs. normal group. Therefore, we consider that DM-associated the hyperglycemia causes atrophy of the articular disc and microangiopathy of the capillary of the retrodiscal tissue in GK rats.

Angioarchitecture and morphology of temporomandibular joint of Monodelphis domestica.

The opossum Monodelphis domestica presents movement of the temporomandibular joint (TMJ) reflecting adaptation to eating habits similar to movement in humans, but the structure of the TMJ is not yet known. Thus, nine young M. domestica, of both sexes were weighed, anesthetized with xylazine (10 mg kg(-1) ), and ketamine (70 mg kg(-1) ) and processed for: 1. The analyses of the macroscopic angioarchitecture after latex injection, as well as the topography of the TMJ; 2. The analysis of microvascularization after injection of Mercox resin and corrosion of soft tissue with NaOH using scanning electron microscopy and; 3. The histological evaluation of the TMJ with an optical microscope. Macroscopic analysis of the latex injected vessels revealed the distribution of the arteries from the common carotid artery, receiving branches of the superficial temporal and maxillary arteries. The mandibular condyle has the long axis in the lateral-lateral direction, and is convex in the anterior-posterior direction. Its topography was determined in relation to the eye and external acoustic meatus. With scanning electron microscopy, microvascularization consists of arterioles of varying diameter (85-15 µm) of the meandering capillary network in the retrodiscal region, and a network of straight capillaries in the TMJ anterior region. Via light microscopy the TMJ has similar histological features to those of humans. These macroscopic, microscopic and ultrastructural data from TMJ of the M. domestica could be a suitable model for TMJ physiology and pathophysiology studies for then speculate on possible human studies. Microsc. Res. Tech. 79:806-813, 2016. © 2016 Wiley Periodicals, Inc.

Contribution of synovial lining cells to synovial vascularization of the rat temporomandibular joint.

The lining layer of the synovial membrane in the temporomandibular joint (TMJ) contains two types of lining cells: macrophage-like type A and fibroblast-like type B cells. The type B cells are particularly heterogeneous in their morphology and immunoreactivity, so that details of their functions remain unclear. Some of the type B cells exhibit certain resemblances in their ultrastructure to those of an activated capillary pericyte at the initial stage of the angiogenesis. The articular surface, composed of cartilage and the disc in the TMJ, has few vasculatures, whereas the synovial lining layer is richly equipped with blood capillaries to produce the constituent of synovial fluid. The present study investigated at both the light and electron microscopic levels the immunocytochemical characteristics of the synovial lining cells in the adult rat TMJ, focusing on their contribution to the synovial vascularization. It also employed an intravascular perfusion with Lycopersicon esculentum (tomato) lectin to identify functional vessels in vivo. Results showed that several type B cells expressed desmin, a muscle-specific intermediate filament which is known as the earliest protein to appear during myogenesis as well as being a marker for the immature capillary pericyte. These desmin-positive type B cells showed immunoreactions for vimentin and pericyte markers (neuron-glial 2; NG2 and PDGFRß) but not for the other markers of myogenic cells (MyoD and myogenin) or a contractile apparatus (αSMA and caldesmon). Immunoreactivity for RECA-1, an endothelial marker, was observed in the macrophage-like type A cells. The arterioles and venules inside the synovial folds extended numerous capillaries with RECA-1-positive endothelial cells and desmin-positive pericytes to distribute densely in the lining layer. The distal portion of these capillaries showing RECA-1-immunoreactivity lacked lectin-staining, indicating a loss of blood-circulation due to sprouting or termination in the lining layer. The desmin-positive type B and RECA-1-positive type A cells attached to this portion of the capillaries. Some capillaries in the lining layer also expressed ninein, a marker for sprouting endothelial cells, called tip cells. Since an activated pericyte, macrophage and tip cell are known to act together at the forefront of the vessel sprout during angiogenesis, the desmin-positive type B cell and RECA-1-positive type A cell might serve as these angiogenic cells in the synovial lining layer. Tomato lectin perfusion following decalcification would be a highly useful tool for research on the vasculature of the mineralized tissue. Use of this technique combined with immunohistochemistry should permit future extensive investigations on the presence of the physiological angiogenesis and on the function of the lining cells in the synovial membrane.

Anatomic study of the distance between the articular eminence and foramen spinosum and foramen spinosum and petrotympanic fissure.

PURPOSE: The middle meningeal artery is in close proximity to the medial aspect of the temporomandibular joint (TMJ). A major potential complication of surgery in the area of the TMJ is possible severance of the middle meningeal artery. An understanding of the relationship of the middle meningeal artery to easily identifiable landmarks lateral to the TMJ can help prevent the complications associated with TMJ surgery. The aim of the present study was to define the location of the middle meningeal artery by relating the distance between the easily identifiable bony landmarks of the articular eminence, petrotympanic fissure, and foramen spinosum. MATERIALS AND METHODS: Using a cross-sectional study design, we selected dried skulls from the Hamman-Todd skeleton collection at the Cleveland Museum of Natural History that were older than 20 years of age at death. The primary study variables were the distances between the articular eminence and foramen spinosum and the foramen spinosum and petrotympanic fissure. To appropriately analyze the variables, stratifications of age, gender, race, and anatomic location were applied. To measure the relationship between the stratifications and distances, a multivariate analysis of variance test was performed. The statistical results were deemed significant at P < .05. RESULTS: The sample consisted of 354 skulls or a total of 708 complexes. In analyzing the data, we noted that the only stratifications that bore any statistical significance were gender, with P < .0001, and the race-distance correlation, with a P value of .0007. CONCLUSIONS: The results of the present study suggest a definite difference in regard to gender on the distance between both sets of anatomic landmarks. Future studies could be tailored to further explore the effect of age on the distance, as a slight correlation was noted in our study.

Synovial tissue in internal derangement of temporomandibular joint.

The aim of this study was to examine the changes of the synovial tissue in rabbit temporomandibular joint (TMJ) internal derangement (ID) models using light and electron microscope. Thirteen rabbits were included in our study. The right TMJ of all animals were used as the experimental group while the left ones as the control group. ID model was established by using elastic rubber rope to stretch anteriorly. Synovial tissues were collected and examined by light and electron microscope to observe microstructure and ultrastructure changes after establishing the model. CD34 was used to count small blood vessels. A paired t test was performed with SPSS 16.0 software package to compare the data of the experimental and the control side. The average number of small blood vessels in the experimental side was significantly greater than the control side both in the first and second week. Numerous synovial cells of type A and type B were detected under electron microscope, and type A cells shrunk after a period of time. This study is helpful to understand the development of the TMJ intra-articular adhesion.

The difficult relationship between occlusal interferences and temporomandibular disorder - insights from animal and human experimental studies.

The aetiology of temporomandibular disorder (TMD) is multifactorial, and numerous studies have addressed that occlusion may be of great importance. However, whether occlusion plays a crucial role in the pathogenesis of TMD remains controversial. Study designs utilising animal models have been used to study the effects of artificial occlusal alterations. Experimental traumatic occlusion affects blood flow in the temporomandibular joint and results in changes in the condylar cartilage, and artificial occlusal interference induces masticatory muscle nociceptive responses that are associated with peripheral sensitisation and lead to central sensitisation, which maintains masticatory muscle hyperalgesia. The possibility that occlusal interference results in TMD has been investigated in humans using a double-blind randomised design. Subjects without a history of TMD show fairly good adaptation to interferences. In contrast, subjects with a history of TMD develop a significant increase in clinical signs and self-report stronger symptoms (occlusal discomfort and chewing difficulties) in response to interferences. Meanwhile, psychological factors appear meaningful for symptomatic responses to artificial interferences in subjects with a history of TMD. Thus, individual differences in vulnerability to occlusal interferences do exist. Although there are advantages and disadvantages to using human and animal occlusal interference models, these approaches are indispensable for discovering the role of occlusion in TMD pathogenesis.

Vascularization of the mandibular condylar head with respect to intracapsular fractures of mandible.

BACKGROUND: Causes of mandibular condylar (condylar) head necrosis as a consequence of intracapsular mandibular fractures are still a subject of controversy. OBJECTIVES: To investigate why in some cases of intracapsular fractures condylar head necrosis occurs. MATERIAL: 58 human heads from the collection of Head and Neck Clinical Anatomy Laboratory, from the Institute of Physiology and Pathology of Hearing, Warsaw, Poland, constituted the material. STUDY: Head arterial tree injections, anatomical preparation with the use of standard set of microsurgical equipment and an operating microscope. RESULTS: The main source of condylar head vascularization is the inferior alveolar artery, supplying bone marrow of the whole mandible as well as its cortical layer. Additional arterial blood supplying comes from a various number (2-7) of branches supplying the temporomandibular joint capsule. They originate directly from the maxillary artery or from its primary branches: masseteric artery, external pterygoid artery or superficial temporal artery. Two rare variants of accessory mandibular head vascularization were encountered. The first (2 cases) was an arterial branch from the maxillary artery and the second (1 case) was a branch from the external pterygoid artery. In these cases the arterial supply of lateral part of temporomandibular joint capsule from other sources was reduced. CONCLUSION: Fractures resulting in the lateral part of the condylar head in isolation could be potentially threatened by necrosis because of poor vascularization.

Contextual knowledge configures attentional control networks.

Contextual cues are predictive and provide behaviorally relevant information; they are not the main objective of the current task but can make behavior more efficient. Using fMRI, we investigated the brain networks involved in representing contextual information and translating it into an attentional control signal. Human subjects performed a visual search task for a low-contrast target accompanied by a single non-target that was either perceptually similar or more salient (i.e., higher contrast). Shorter reaction times (RTs) and higher accuracy were found on salient trials, suggesting that the salient item was rapidly identified as a non-target and immediately acts as a spatial "anti-cue" to reorient attention to the target. The relative saliency of the non-target determined BOLD responses in the left temporoparietal junction (TPJ) and inferior frontal gyrus (IFG). IFG correlated with RT specifically on salient non-target trials. In contrast, bilateral dorsal frontoparietal regions [including the frontal eye fields (FEFs)] were correlated with RT in all conditions. Effective connectivity analyses using dynamic causal modeling found an excitatory pathway from TPJ to IFG to FEF, suggesting that this was the pathway by which the contextual cue was translated into an attentional control signal that facilitated behavior. Additionally, the connection from FEF to TPJ was negatively modulated during target-similar trials, consistent with the inhibition of TPJ by dorsal attentional control regions during top-down serial visual search. We conclude that left TPJ and IFG form a sensory-driven network that integrates contextual knowledge with ongoing sensory information to provide an attentional control signal to FEF.

Percentage of lateral pterygoid muscle inserted in the disc of human temporomandibular joint / Porcentaje del músculo pterigoideo lateral inserto en el disco de la articulación temporomandibular humana

Insertion of the upper head of the lateral pterygoid (UHLP) in the temporomandibular joint disc (TMJ) has been linked to anterior displacement of the disc and temporomandibular disfunction. The aim of this study was to determine in human adults, the percentage of muscle fiber in the upper head of the lateral pterygoid muscle inserted in the articular disc. A systematic review of the literature was designed beginning with articles published in Medline, Lilacs and Scielo data bases between the years 1990 and 2010. Key words "Lateral Pterygoid Muscle" and Pterygoid Lateral Muscle" were used, and the term MeSH "Pterygoid Muscle" with Boolean OR "Lateral Ptrerygoid Muscle" AND "Insertion" and the free terms "Pterygoid Lateral Muscle Disc Articular" and "Pterygoid lateral Muscle Meniscus". Of the 156 articles obtained and analyzed, 18 articles meeting eligibility criteria were selected. Based on those articles the percentage of insertion of the CSPL in the TMJ disc was evaluated, each one was subsequently assigned a level of evidence according to OCEBM Oxford Centre Evidence Based Medicine. Only four articles answered the research inquiry, three studies were histological and one used imaging techniques with cross section slices with an adequate evidence level (1B). However, results differed with insertion percentages from 2 percent to 69.8 percent being reported in the superior head of the lateral pterygoid muscle in the articular disc.

La actividad de la inserción de la cabeza superior del pterigoideo lateral (CSPL) en el disco de la articulación temporomandibular (ATM) ha sido vinculada al desplazamiento anterior del disco y disfunción temporomandibular. El propósito de este estudio fue determinar el porcentaje de fibras musculares de la cabeza superior del músculo pterigoideo lateral que se insertan en el disco articular, en humanos adultos. Se diseñó una revisión sistemática de la literatura a partir de artículos primarios publicados en las bases de datos Medline, Lilacs y Scielo entre los años 1990 y 2010. Se utilizaron las palabras clave "Músculo Pterigoideo Lateral" y "Pterygoid Lateral Muscle", el Término MeSH: "Pterygoid Muscle" con los boleanos OR "Lateral Pterygoid Muscle" AND "Insertion" y los Términos Libres: "Pterygoid Lateral Muscle Disc Articular" y "Pterygoid lateral Muscle Meniscus". Se obtuvieron 156 artículos, los cuales fueron analizados y se seleccionaron 18 que cumplieron con los criterios de elegibilidad. En base a estos artículos se evaluó el porcentaje de inserción de la CSPL en el disco de la ATM, posteriormente a cada uno se les otorgó un nivel de evidencia de acuerdo a la clasificación de Oxford Centre Evidence Based Medicine (OCEBM). Solo 4 artículos respondieron a la pregunta de investigación, 3 estudios fueron histológicos y 1 imagenológico, todos con diseños de cortes transversales con buen nivel de evidencia (1b). Sin embargo los resultados fueron disímiles, reportándose porcentajes de inserción del 2 al 69,8 por ciento de la cabeza superior del pterigoideo lateral en el disco articular.

Chronic orofacial pain.

Chronic orofacial pain (COFP) is an umbrella term used to describe painful regional syndromes with a chronic, unremitting pattern. This is a convenience term, similar to chronic daily headaches, but is of clinically questionable significance: syndromes that make up COFP require individually tailored diagnostic approaches and treatment. Herein we describe the three main categories of COFP: musculoskeletal, neurovascular, and neuropathic. For many years, COFP and headache have been looked upon as discrete entities. However, we propose the concept that because COFP and headaches share underlying pathophysiological mechanisms, clinical characteristics, and neurovascular anatomy, they should be classified together.

[Diagnosis and treatment of temporo-mandibular disorders in orthodontics]. / Détection et thérapeutique des troubles temporo-mandibulaires en orthodontie.

Orthodontists are fully prepared to treat the problems of occlusion that they are called upon to deal with every day. On the other hand temporo-mandibular joint disorders present more obscure difficulties from the point of view of detection and diagnosis as well the management of their treatment. That is why a profound understanding of the anatomical and physiological functioning of the temporo-mandibular joint has become indispensable for today's orthodontists who are now asked to detect and diagnose an assortment of TMJ disturbances whose etiology may vary greatly. By performing a rigorous diagnostic procedure, based on a thorough clinical examination supported by careful axiographic and radiological studies, of temporo-mandibular malfunctioning and its underlying etiological causes, which are primarily dento-alveolar and occlusal in nature, orthodontists will be able to adopt an appropriate therapeutic approach that might be purely orthodontic or multi-disciplinary and carried out with the collaboration of specialists in occlusion, oral surgery, and even osteopathy.

The levels of vascular endothelial growth factor in the synovial fluid correlated with the severity of arthroscopically observed synovitis and clinical outcome after temporomandibular joint irrigation in patients with chronic closed lock.

OBJECTIVE: This study aimed to investigate the level of vascular endothelial growth factor (VEGF) in the temporomandibular joint (TMJ) synovial fluid (SF) and the severity of arthroscopically observed synovitis before and after visually guided TMJ irrigation (VGIR) in patients with chronic closed lock (CCL). In addition, the findings were correlated with the clinical outcome. STUDY DESIGN: Twenty-four patients with unilateral CCL, who underwent a second VGIR either as a repeated therapeutic TMJ irrigation or as a follow-up arthroscopy, were enrolled in the study. They were divided into either successful (s-group; n = 11) and unsuccessful (u-group; n = 13) groups. The VEGF level in the aspirated SF and the severity of synovitis were compared between the s- and u-groups. In each group, the same parameters were compared before and after VGIR. The correlation of the VEGF level with the severity of synovitis was also studied. RESULTS: At the first VGIR, the VEGF levels showed no significant differences when comparing s- and u-groups. At the second VGIR, the VEGF level was significantly higher in the u-group. The VEGF level significantly decreased after the first VGIR in the s-group but remained unchanged in the u-group. There was no significant correlation between the VEGF level and the severity of synovitis. CONCLUSIONS: The level of VEGF in TMJ SF seems to reflect the clinical status in patients with CCL. Moreover, VEGF may be an important target molecule in future chemotherapy of TMJ CCL.

Influence of gum-chewing on the haemodynamics in female masseter muscle.

Blood flow in active skeletal muscles provides energy substrate, oxygen and reduction of excessive heat and metabolic by-products. Although cyclic jaw motions such as those during mastication and speech articulation are the primitive oro-facial functions, possible effects of the cyclic muscle contractions on the intramuscular haemodynamics of the jaw muscles remains scarcely known. We investigated the masseteric haemodynamics during and after gum-chewing. Ten healthy female adults participated in the study. Electromyography, kinetics of masseter muscle oxygenation, electrocardiogram and blood pressure were recorded simultaneously. The subjects were asked to perform gum-chewing and cyclic jaw motion without gum bolus (empty-chewing task). The haemodynamics parameters were compared between the two experimental conditions. During gum-chewing task, deoxygenated haemoglobin and sympathetic nerve activity increased, while tissue blood oxygen saturation decreased. Blood pressure and parasympathetic nerve activity did not change. The overall behaviour of haemodynamic parameters during empty-chewing task was similar to that observed during gum-chewing task. However, the latency periods from the end of chewing until significant changes in the haemodynamic parameters were notably shorter (P < 0.05) in gum-chewing task as compared with those associated with empty-chewing task. The duration of the changes was shorter with empty-chewing than with gum-chewing. Fluctuations in masseter muscle haemodynamics associated with chewing jaw movement differed depending on the level of muscle contraction during movement. The differences became statistically significant immediately after the commencement of chewing and after the cessation movement. During the chewing movement, automatic nerve activities increased in response to the level of muscle contraction during movement.

Masseteric artery: anatomic location and relationship to the temporomandibular joint area.

PURPOSE: This study was performed to determine the precise location of the masseteric artery in relation to the temporomandibular joint region to reduce the risk of injury during surgery. MATERIALS AND METHODS: A careful dissection of 16 intact human cadaveric head specimens was carried out to determine the course of the masseteric artery. The location of the masseteric artery was then determined in relation to 3 points in the anterior-posterior plane between the mandibular condyle and the coronoid process: 1) the anterior-superior aspect of the condylar neck, 2) the most inferior aspect of the articular tubercle, and 3) the inferior aspect of the sigmoid notch. RESULTS: The mean distance of the masseteric artery to the most anterior-superior aspect of the condylar neck was 10.3 mm; to the most inferior aspect of the articular tubercle, 11.4 mm; and to the most inferior aspect of the sigmoid notch, 3 mm. CONCLUSIONS: These results show that there is considerable variability in the location of the masseteric artery. Although it is generally closest to the depth of the sigmoid notch, which can explain why this vessel can be easily damaged during intraoral vertical ramus osteotomies, in some instances it can also be close to either the neck of the condylar process or the coronoid process. The data provided in this study can serve as a guide for locating the vessel when operating in these areas.