Effects of Different Stabilization Splint Thicknesses on Stress Distribution in Temporomandibular Joint for Patients with Anterior Disc Displacement with Reduction / 医用生物力学

Objective To compare the stress distributions in temporomandibular joint (TMJ) for patients with bilateral anterior disc displacement with reduction (ADDwR) after wearing stabilization splints with two different thicknesses during prolonged clenching by using three-dimensional (3D) finite element methods. Methods The 3D TMJ finite element models were constructed based on CT and MRI image data when the patient was biting in maximum intercuspation (working condition 1), on 3 mm thickness splint (working condition 2) and on 5 mm thickness splint (working condition 3), respectively. The von Mises stresses in the articular cartilages ,the TMJ disc and bilaminar zone under 3 working conditions were evaluated after the maximum jaw-closing forces were applied to the mandible for 60 s. Results The von Mises stress of left TMJ was bigger than that of right TMJ under each working condition. After wearing the 3 mm thickness splint, the disc was not recaptured, the stress was concentrated at the posterior band and bilaminar zone of the disc, and the stress on bilateral TMJ was significantly increased. After wearing the 5 mm thickness splint, the right disc was recaptured, the maximum stress was located at intermediate zone of the disc, and the von Mises stresses of articular cartilages and bilaminar zone were decreased by about 40%. However, the left disc was not recaptured, and the von Mises stresses of glenoid fossa cartilage and bilaminar zone were only slightly decreased by about 6%. Conclusions Different thicknesses of occlusal splints lead to different stresses and stress distribution patterns in TMJ of patients with ADDwR. The 5 mm thickness stabilization splint can reduce the stress of glenoid fossa cartilage and bilaminar zone in ADDwR patients. Disc recapture is helpful for ADDwR patients to relieve TMJ stress. When using stabilization splints for the treatment of ADDwR patients, on the premise of comfort wearing, a thicker splint can achieve more favorable stress distributions.

A panoramic study of the morphology of mandibular condyle in a sample of population from Basrah City / Estudio panorámico de la morfología del cóndilo mandibular en una muestra de población de la ciudad de Basora

SUMMARY: The study aims to evaluate the morphological variation of mandibular condyle This analysis was composed of 450 digital orthopantomograms taken for routine investigation to assess the morphology of 900 condylar heads. Condylar morphology was classified into four types (oval, bird beak, diamond and crooked finger). Most common occurring shape were evaluated, symmetry of condylar shape and most common combinations of the condylar shapes present in population were assessed. Out of 900 mandibular condyle, type 1(oval) of condyle was the most commonly appearing shape (56 %), followed by type 3 (diamond), type 2(bird beak) and finally type 4 (crooked finger). Symmetry was seen in 74.2 % of the total sample with the oval-oval was the most commonly occurring. Routine use of orthopantomography can assist dentist in assessment of condylar morphology alterations. Oval shape was the most common in all age groups in males and females. More studies on Iraqi population evaluating mandibular condyle are needed to provide standardized values for mandibular anatomical parts.

RESUMEN: El objetivo del presente estudio fue evaluar la variación morfológica del cóndilo mandibular. El análisis se realizó en 450 ortopantomogramas digitales en una investigación de rutina para evaluar la morfología de 900 cabezas condilares. La morfología condilar se clasificó en cuatro tipos (ovalada, pico de pájaro, diamante y dedo torcido). Se evaluó la forma más común de ocurrencia, la simetría de la forma condilar y las combinaciones más comunes en la población. De 900 cóndilos mandibulares, el tipo 1 (ovalado) de cóndilo apareció con mayor frecuencia (56 %), seguido del tipo 3 (diamante), el tipo 2 (pico de pájaro) y finalmente el tipo 4 (dedo torcido). Se observó simetría en el 74,2 % de la muestra total, siendo el óvalo-óvalo el que se presentó con mayor frecuencia. El uso rutinario de la ortopantomografía puede ayudar al dentista a evaluar las alteraciones de la morfología condilar. La forma ovalada fue la más común en todos los grupos etarios en hombres y mujeres. Se necesitan más estudios sobre la población iraquí que evalúen el cóndilo mandibular para proporcionar valores estandarizados para evaluar la anatomía mandibular.

The Influence of Facial Asymmetry on Stress Distributions in Temporomandibular Joints for Patients with Mandibular Prognathism / 医用生物力学

Objective To explore the effects of facial asymmetry on stress distributions in temporomandibular joints (TMJs) for patients with mandibular prognathism. Methods Eight 3D maxillofacial models were established in MIMICS based on cone-beam CT of 4 mandibular prognathism patients with asymmetry and 4 mandibular prognathism patients without asymmetry. Muscle forces and boundary conditions corresponding to the unilateral occlusion (unilateral molar chewing) were applied on the models in ABAQUS. The maximum and the minimum principal stresses of TMJ were chosen for analysis. Results There were significant differences in the maximum and minimum principal stresses at the condyles between the mandibular prognathism patients with and without facial asymmetry under unilateral occlusions (P<0-05). Compared with patients without facial asymmetry, the stresses on the condyle in patients with asymmetry increased by 2-3 times, and the stresses on articular fossa increased by 5-7 times. Among the mandibular prognathism patients with asymmetry, the stresses of the ipsilateral TMJ in patients with temporomandibular disorder (TMD) were significantly higher than those in patients without TMD. Conclusions Facial asymmetry increased the stresses of the articular fossa and condyle in patients with mandibular prognathism. TMD would cause greater stresses in ipsilateral TMJ of the mandibular prognathism patient with asymmetry. Therefore, different treatment strategies should be considered for mandibular prognathism with facial asymmetry.

The Profile of Oral Lesions in Patients Attending Oral Diagnosis Clinic at the College of Dentistry, University of Basra, Iraq

Objective: Oral health refers to the health of our mouth and ultimately, supports and reflects the health of the entire body. So this study is designed to assess the profile of oral lesions in patients attending an oral diagnosis clinic at a College of Dentistry, University of Basra, Iraq. Patients and methods: The study was conducted in an outpatient clinic of Oral Diagnosis Department, College of Dentistry. Total 13184 patients attended during a period of study from October 2014 to June 2016; among them, 494 patients have oral lesions. The examination was done by an oral medicine specialist. The questionnaire form was filled for each patient. Results: Among the 13184 dental patients, only 494 (3.74%) patients had oral lesions; 232 (47%) were males and 262 (53%) were females. The most frequent age group was 20-39 years for 50.2% of the total examined patients. The most common oral lesions diagnosed by this study were the ulcerative lesions found in 184 (37.2%) patients, while myofascial pain dysfunction syndrome (MFPDS) was found in 113 (22.9%) patients. The ulcerative lesions were more common in males than in females; while MFPDS were more in females than in the males. The most common site affected by oral lesions was Temporomandibular joint (TMJ) found in 115 (23.3%) patients and lower lip affected by oral lesions found in 108 (21.9%) patients; while buccal mucosa affected was found in 71 (14.4%) patients from the total patients. Conclusion: The routine examination of the oral cavity is essential in identifying several oral lesions and this helps to establish early diagnosis and accurate treatment to get a better prognosis, in addition to that it establishes the baseline data in oral diseases for future oral health programs.

Prevalencia y distribución de signos degenerativos en cóndilo de la ATM presentes en radiografías panorámicas en población chilena / Prevalence and distribution of degenerative signs in ATM condyle in panoramic radiographs in a Chilean population

La articulación temporomandibular (ATM), como todas las articulaciones, es afectada por enfermedades inflamatorias o degenerativas, traumatismos, malformaciones, infecciones, quistes y tumores. La artrosis u osteoartrosis (OA) es la enfermedad degenerativa más frecuente de las articulaciones del cuerpo humano, incluyendo la ATM. El propósito de este estudio fue determinar la prevalencia de signos imagenológicos de trastornos degenerativos en el proceso condilar de la ATM, presentes en radiografías panorámicas digitales (RPD) de población chilena. Para ello se realizó un estudio de corte transversal que utilizó 651 radiografías de individuos adultos, en las que se buscó la presencia de los siguientes signos imagenológicos de osteoartrosis: esclerosis, pérdida de la cortical, erosión, osteofitos y quistes endocondrales. La prevalencia de signos radiográficos de OA fue de un 35 % (n=230); donde el 50 % de los individuos con signos de OA fueron mayores de 50 años, mientras la diferencia se distribuyó de forma homogénea en los distintos rangos etáreos. El signo más prevalente fue el osteofito (25 %) y la pérdida de cortical fue la menos observada (3 %). Además, la esclerosis presentó una prevalencia del 6 %, la erosión del 4 % y los quistes endocondrales del 6 %. Por su parte la frecuencia de signos observada en hombres fue mayor, detectándose un aumento en relación directa con la edad independiente del sexo. La radiografía panorámica por su accesibilidad, baja dosis de radiación y constituir un examen de rutina, constituye un medio apropiado para pesquizar hallazgos de signos degenerativos de la ATM.

The temporomandibular joint (TMJ), like all joints, is affected by inflammatory or degenerative diseases, traumatisms, malformations, infections, cysts and tumors. Osteoarthrosis (OA) is the most common degenerative disease of the joints of the human body, including the temporomandibular joint. The purpose of this study was to estimate the prevalence of imaging signs of degenerative disorders in the TMJ condyle, present in digital panoramic radiographs in Chilean population. A cross-sectional study was conducted using 651 radiographs of adult individuals. The presence of the following imaging signs of osteoarthrosis was recorded: sclerosis, cortical loss, erosion, osteophytes and endochondral cysts. The prevalence of radiographic signs of OA was 35 % (n = 230); where 50 % of the individuals with signs of OA were older than 50 years, while the difference was distributed homogeneously in the different age ranges. The most prevalent sign was osteophyte (25 %) and cortical loss was the least observed (3 %). In addition, sclerosis presented a prevalence of 6 %, erosion of 4 % and endochondral cysts of 6 %. On the other hand, the frequency of signs observed in men was greater, detecting an increase in direct relation with age independent of sex. The data of this study allows us to conclude that the prevalence of OA in the studied population was 35 % with a higher representation in men and older people. Both the value of the prevalence of OA and that corresponding to each sign are affected by the modality of radiographic analysis and methodological considerations.

Ruidos articulares en pacientes rehabilitados con prótesis parcial removible / Articular noise in patients rehabilitated with removable partial dentures

Resumen: Los ruidos articulares constituyen junto a las restricciones mandibulares, los signos clásicos de los trastornos temporomandibulares (TTM) que pueden ir acompañados por sintomatología dolorosa. Su etiología multifactorial reconoce estrés emocional, traumatismo, dolor profundo, actividad parafuncional y problemas oclusales. El objetivo de este estudio descriptivo transversal fue determinar la frecuencia y tipos de ruidos articulares y su relación con las clases de Kennedy y la presencia o ausencia de sintomatología dolorosa. Se realizó exploración táctil y auscultación de la articulación temporomandibular (ATM) a 50 pacientes concurrentes a la Cátedra Clínica de Prótesis I curso. La incidencia de ruidos articulares fue del 48%: clics simples 48.15%, clics recíprocos 25.9%, pop 18.5%, y crepitaciones 7.4%. La anamnesis mostró presencia de dolor en un 14%. La coincidencia de ambos signos (dolor y ruido) coincidió en un 25%. Se presentó la alta incidencia de clics simples relacionada con la clase II de Kennedy.

Abstract: Mandibular noises, along with mandibular restrictions, constitute classical signs of temporomandibular joint disorders (TMJD) which can be accompanied with painful symptomatology. Its multifactorial etiology encompasses emotional stress, trauma, deep pain, parafunctional activity and occlusal problems. The aim of the present transversal and descriptive study was to determine frequency and types of articular noises and their relationship with Kennedy's classes, as well as presence or absence of painful symptomatology. A total of 50 patients attending the course of prosthesis clinical chair 1 were examined, they were subjected to tactile exploration and temporomandibular Joint (TMJ) auscultation. Frequency of articular noises was 48%, simple clicks 48.15%, reciprocal clicks 25.9%, pops 18.5% and crepitations 7.4%. Clinical history revealed presence of pain in 14% of cases. Coincidence of both signs (pain and noise) occurred in 25%. High incidence of simple clicks related to Kennedy's class II was observed.

The clinical effects of upper articular cavity injection with hyaluronate combined with Twin-block in the treatment of temporomandibular joint clicks / 实用口腔医学杂志

Objective: To observe the clinical effects of upper articular cavity injection with hyaluronate(HA) combined with Twinblock in the treatment of temporomandibular joint(TMJ) clicks. Methods: 60 patients with TMJ clicks were divided into 3 groups(n = 20) and were treated by articular cavity injection combined with Twin-block(group 1),Twin-block only(group 2) and injection of sodium hyaluronate gel(group 3) respectively. The effects were evaluated and compared before and after treatment by both doctors and patients. Results: The effective rate of group 1,2 and 3 was 95％,and 65％ respectively(P ＜ 0. 05). After treatment the TMJ clicks were almost dispeared in group 1,remitted in group 2 and slightly remitted in group 3. Conclusion: The articular cavity injection of HA combined with Twin-block is more effective in the treatment of TMJ clicks than Twin-block or articular cavity injection of HA.

The effects of Herbst two phase treatment on temporomandibular joint position analyzed by CBCT / 实用口腔医学杂志

Objective:To assess the effects of Herbst two phase treatment on temporomandibular joint(TMJ) position analyzed by CBCT.Methods:15 patients of permanent dentition with class Ⅱ malocclusion combined with mandibular retrusion were treated by Herbst appliance as the 1st phase,then the 4 1st premolars of each patient were extracted,the fixed appliance of edgewise was applied as the 2nd phase of treatment.CBCT examination was carried out at the following stages:2 weeks before Herbst treatment(T1),at the start of the treatment when Herbst appliance was placed(T2),immediately after Herbst appliance was removed(T3) and immediately after the edgewise appliance was removed(T4).The InvivoDental software was used to calculate the joint space of TMJ from the three -dimensional CBCT images.The acquired data were then statistically analyzed.Results:During T1-T2-T3 stages,the anterior joint space was decreased and then increased,superior joint space and posterior joint space were increased and then decreased.During T3-T4 stages,the superior joint space and posterior joint space decreased further,but anterior joint space did not change.No significant difference was found in the anterior joint space,superior joint space and posterior joint space between T1 and T4 stage.Conclusion:At the start of treatment with Herbst appliance,the condyle is displaced in an anterior and inferior direction.At the end of functional treatment,especially the end of two phase treatment,the condyle is drawed back nearly to the original position.

The effects of recombinant human interleukin-1 receptor antagonist on the cartilage repair in rat temporomandibular joint with osteoarthritis / 实用口腔医学杂志

Objective:To investigate the effects of recombinant human interluekin-1 receptor antogonist (rhIL-1Ra) on the cartilage repair in rat temporomandibular joint(TMJ) with osteoarthritis(OA).Methods:Collagenase-Ⅱ was injected into bilateral TMJs of 24 adult rats for the induction of bilateral TMJOA,1 week after injection,5μg rhIL-1Ra(diluted in 0.05 ml normal saline) was injected into each right TMJ and the left joint received the same amount of normal saline injection as the control.12 animals were sacrificed at 2and 4 weeks after the first injection respectively.HE staining,immunnohistochemical method and RT-PCR examination were conducted.Mankins scere was used to evaluate the TMJOA degree.1 adult SD rat was used as healthy control,and sacrificed at 2 weeks of the experiment.Results:The TMJs of both sides showed typical OA-related cartilage degradation 2 week after IL-1Ra treatment,the Mankin~ score of the IL-1Ra treated and control joints was 1.33±0.52 and 2.00±6.63 (P＞0.05),4 week after treatment that was 3.00± 0.63 and 6.50 ± 0.84 (P＜0.05),respectively.Lower expression of ADAMTS-4 and ADAMTS-5 was observed in the treated joints than in the controls (P＜0.05).Conclusion:Intra-articular injection of IL-1Ra into TMJ can alleviate the cartilage lesion,the mechanism may lie in the inhibition of the expression of ADAMTS-4 and ADAMTS-5.

Analysis on relevant factors in 3D finite element modeling of the temporomandibular joint / 医用生物力学

The biomechanical studies on the temporomandibular Joint（TMJ）are of great importance to understand the origin and progression of TMD disorders. The finite element method can be used to analyze stress/strain distribution patterns in the TMJ tissues after application of force or deformation. However, due to the delicate and complicated anatomical structures of TMJ, modeling research were always time-consuming, expensive and non-repeatable. To explore a more rapid and accurate method for establishment of 3D finite element model of TMJ, the relevant factors such as geometric similarity, biomechanical environment simulation for improving the accuracy of TMJ finite element modeling were summarized.

Sodium hyaluronate injection for the treatment of anterior disc displacement without reduction in the temporomandibular joint: A CBCT evaluation / 实用口腔医学杂志

Objective:To provide imaging evidence for the treatment of anterior disc displacement without reduction by the injection of sodium hyaluronate into temporomandibular joint (TMJ).Methods:40 patients with anterior disc displacement without reduction were injected 3 times with sodium hyaluronate into the TMJ.Patient's TMJ and clinical symptoms were examined 3,9 and 12 months after treatment.The clinical parameters of Fricton's Craniomandibular Index(Fricton index),maximal mouth opening(MMO),pain intensity of a visual analog scale(VAS) and CBCT radiographic data of 48 TMJs from 40 patients were analysed.Results:The CBCT images showed that at 9 and 12 months follow-up the surface of the condylus became smooth,the density of the cortical bone and the adjacent subcortical bone increased and osteophyte in condylar head decreased(P =0.026,P =0.001).As for disc displacement without osteoarthritts,9 months after treatment condylus were moved forward(P =0.038).VAS and Fricton index were reduced(P ＜0.05),MMO was increased (P ＜ 0.05).3-12 months after treatment,there was no statistical difference of Fricton index (P ＞ 0.05).Conclusion:Injection of sodium hyaluronate into TMJ can remodel the condylar bone surface but cant make condyle back to the middle of acetabulum.

Clinical analysis of 10 cases with traumatic extra-articular ankylosis of temporomandibular joint / 实用口腔医学杂志

The data of 10 cases of traumatic extra-articular ankylosis of temporomandibular joint(TMJ),including the type of trauma and the type of ankylosis,pathology,treatment method,prognosis,and so on were collected and analyzed.A reference of diagnosis and treatment is provided.

Construction of a 3D finite element model of temporomandibular joints including the musculoskeletal system / 医用生物力学

Objective To discuss the feasibility of constructing a 3D finite element model of the temporomandibular joint (TMJ) including the musculoskeletal system based on imaging and anatomy, and to provide new ideas of modeling for TMJ biomechanical researches. Methods CT images of the skull, MRI images of masticatory muscles and bilateral TMJ from No.23 Chinese virtual human in the second generation were collected and imported in batches into Mimics in format of DICOM for 3D reconstruction. Then the model was integrated and optimized by Geomagic Studio, and the TMJ capsule and articular cartilage were also constructed. After the material properties of TMJ tissues were defined, a 3D finite element model of TMJ including the musculoskeletal system was finally constructed by ANSYS. Results The 3D finite element model of TMJ with the musculoskeletal system was constructed, including TMJ disc, articular cartilage, TMJ capsule, maxilla (including zygoma and nasal), mandible, sphenoid, temporal bones (including part of parietal), maxillary teeth, mandibular teeth, temporalis muscles, masseter muscles, medial/lateral pterygoid muscles, temporomandibular ligaments, sphenomandibular ligaments and sylomandibular ligaments. Conclusions Based on CT and MRI images and anatomy, the 3D finite element model of TMJ including the musculoskeletal system can be precisely and feasibly constructed by Mimics, Geomagic Studio and ANSYS. This model can restore the biomechanical environment of the TMJ, provide new ideas of modeling for biomechanical researches on the TMJ, and offer the simulation platform for visualization treatment of TMJ disease in clinic.

Diseño de un dispositivo como herramienta diagnóstica en trastornos témporomandibulares / Design of a device as a diagnostic tool for temporomandibular joint disorder

En la práctica odontológica se puede evidenciar una insatisfacción, de los profesionales de la odontología, al solo contar con una imagen diagnóstica de una radiografía panorámica y lo inaccesible que resulta adquirir otros equipos que puedan aportar información para estudiar las afecciones en la Articulación Témporo Mandibular (ATM). Esta investigación orientada al diseño de un dispositivo receptor de imagen que asemeja un arco facial y un audífono, el cual, a su vez posee cámaras para la obtención de imágenes. A su vez, apoyado por un software (matlab) que interpreta los cambios de la imagen como una línea de desplazamiento, arrojando valores que son llevados a formar parte de un diagnóstico, en el estudio de desórdenes témporomandibulares. Este proyecto se enmarco en la modalidad de proyecto factible, con enfoque tecnicistas. Se utilizó una encuesta como técnica de recolección de datos y como instrumento se uso un cuestionario estructurado con preguntas dicotómicas. El estudio se aplico a docentes de la asignatura Oclusión y Rehabilitación Protésica, del Departamento de Prostodoncia y Oclusión de la Facultad de Odontología de la Universidad de Carabobo. Se evidencio que la mayoría de los docentes manifestaron poca confianza en los métodos diagnósticos existentes, ya que no ofrecen imágenes dinámicas y son poco accesibles a la población. Además, se encontró que el 100% está de acuerdo que el desarrollo del dispositivo antes mencionado. Se encuentra que este dispositivo seria innovador y cómodo, además de encontrarse una amplia motivación hacia su aplicación...

The purpose of this research is to develop a design of a receiver device supported by software that interprets the changes in an image as a displacement line of the TMJ. This research aims to present a device as a diagnostic tool for the témporomandibular joint disorder to the professors of the Faculty of dentistry in Carabobo University. This project was delimited as a workable project with a technicist approach where it is used a survey, as data collection technique and a structured questionnaire with dichotomous questions, as instrument. The study was applied to the professors of occlusion and prosthetic rehabilitation subject of the Faculty of dentistry in Carabobo University having 15 professors. It was found that most of the professors manifest a lack of confidence on the methods to study the TMJ disorders, due to it is unable to show the condylar dynamics and are also expensive for most of the population. Plus, it was evidenced that 100% were agree on develop of the device mentioned before, It´s described as comfortable, being motivated for the application..

Dynamic MRI study on temporomandibular joint and biomechanical analysis / 医用生物力学

Objective To establish a three-dimensional (3D) dynamic model of temporomandibular joint (TMJ) based on data collected from the TMJ movement with multi-level two-dimensional (2D) dynamic magnetic resonance imaging (MRI) and make biomechanical analysis. Methods GE Signa 1.5T TwinSpeed superconductive magnetic resonance scanner was used. TMJs of 2 asymptomatic male volunteers were chosen to be examined with MRI. All the images were imported to the Mimics software. 3D dynamic model of the TMJ was built, and the relationship between the magnitude of mouth opening and the disc transverse diameter was analyzed using linear fitting. Results The 3D dynamic model of TMJ was successfully established. The disc-condyle relationship and the dynamic morphological change of the TMJ disc were showed clearly in this model. The linear fitting equations were y=-0.03x+14.44 (R2=0.591) and y=-0.061x+13.48 (R2=0.306) from volunteers 1 and 2, respectively. A linear trend was observed regarding the relationship between mouth opening position and articular disc transverse diameter. The contact of the condyle surrounded by the TMJ disc varied inversely with the magnitude of mouth opening; the longitudinal diameter of TMJ disc changed along with the magnitude of mouth opening. In the process of mouth opening, the thickest longitudinal diameter of the joint disc was at the middle part of post-zone. The most remarkable changes of the longitudinal diameter of TMJ disc were found at the outer part of the post-zone and the inner part of the mid-zone. Conclusions The 3D dynamic model of TMJ was built successfully to observe the TMJ movement dynamically with 2D dynamic MRI. The model showed the disc-condyle relationship intuitively and precisely, and could be used as an alternative method to make up for the shortage of the 2D static MRI.

Effects of disc displacement on stress distributions in temporomandibular joint / 医用生物力学

Objective To investigate stress distributions on temporomandibular joint (TMJ) with different disc displacements through numerical simulation. Methods A three-dimensional finite element model of normal TMJ including the mandible, teeth, discs and articular cartilage was established according to CT images of a volunteer with asymptomatic joints. Base on the model, four corresponding models with the anterior, posterior, lateral and medial displacement of the disc were developed. Contact elements were considered to simulate the interaction between the discs and articular cartilages of the condyle and the temporal bone. Cable elements were used to simulate the ligaments and attachments of the disc. The muscle forces and boundary conditions corresponding to the centric occlusions were applied on the models. Results The maximum compressive stress occurred at the intermediate zone due to the anterior displacement of the disc, which was as high as 3.23 MPa. The stresses in the model with the posterior, lateral and medial displacements of the disc were higher than the model with the anterior displacement of the disc and healthy TMJ model. The stresses at the back of the articular eminences in four models with disc displacements were much higher than those in healthy TMJ model. However, the effects of disc displacements on the stresses of the condyles were not obvious. Conclusions Disc displacements could cause higher stresses in the discs and at the back of the articular eminences, especially in the model with the posterior, lateral and medial displacements of the disc, which was likely to cause damage to TMJ structure and function.

Improvement of a 4-Channel Spiral-Loop RF Coil Array for TMJ MR Imaging at 7T

PURPOSE: In an attempt to further improve the radiofrequency (RF) magnetic (B1) field strength in temporomandibular joint (TMJ) imaging, a 4-channel spiral-loop coil array with RF circuitry was designed and compared with a 4-channel single-loop coil array in terms of B1 field, RF transmit (B1+), signal-to-noise ratio (SNR), and applicability to TMJ imaging in 7T MRI. MATERIALS AND METHODS: The single- and 4-channel spiral-loop coil arrays were constructed based on the electromagnetic (EM) simulation for the investigation of B1 field. To evaluate the computer simulation results, the B1 field and B1 + maps were measured in 7T. RESULTS: In the EM simulation result and MRI study at 7T, the 4-channel spiral-loop coil array found a superior B1 performance and a higher B1 + profile inside the human head as well as a slightly better SNR than the 4-channel single-loop coil array. CONCLUSION: Although B1 fields are produced under the influence of the dielectric properties of the subject rather than the coil configuration alone at 7T, each RF coil exhibited not only special but also specific characteristics that could make it suited for specific application such as TMJ imaging.

A clinical study on temporalis myofascial flap for adult temporomandibular joint ankylosis