Academic literature on the topic 'Articular disks position'

This article was designed to report the current status of temporomandibular joint disorders (TMDs) and the therapeutic system on the basis of a series of clinical, biomechanical, histological and biochemical studies in our research groups. In particular, we have focused on the association of degenerative changes of articular cartilage in the mandibular condyle and the resultant progressive condylar resorption with mechanical stimuli acting on the condyle during the stomatognathic function. In a clinical aspect, the nature and prevalence of TMDs, association of malocclusion with TMDs, association of condylar position with TMDs, association of craniofacial morphology with TMDs, and influences of TMDs, TMJ-osteoarthritis (TMJ-OA) in particular, were examined. In a biomechanical aspect, the nature of stress distribution in the TMJ from maximum clenching was analyzed with finite element method. In addition, the pattern of stress distribution was examined in association with varying vertical discrepancies of the craniofacial skeleton and friction between the articular disk and condyle. The results demonstrated an induction of large compressive stresses in the anterior and lateral areas on the condyle by the maximum clenching and the subsequent prominent increases in the same areas of the mandibular condyle as the vertical skeletal discrepancy became more prominent. Increase of friction at the articular surface was also indicated as a cause of larger stresses and the relevant disk displacement, which further induced an increase in stresses in the tissues posterior to the disks, indicating an important role of TMJ disks as a stress absorber. In a histological or biological aspect, increase in TMJ loading simulated by vertical skeletal discrepancy, which has already been revealed by the preceding finite element analysis or represented by excessive mouth opening, produced a decrease in the thickness of cartilage layers, an increase in the numbers of chondroblasts and osteoclasts and the subsequent degenerative changes in the condylar cartilage associated with the expression of bone resorption-related factors. In a biochemical or molecular and cellular aspect, excessive mechanical stimuli, irrespective of compressive or tensile stress, induced HA fragmentation, expression of proinflammatory cytokines, an imbalance between matrix metalloproteinases and the tissue inhibitors, all of which are assumed to induce lower resistance to external stimuli and degenerative changes leading to bone and cartilage resorption. Excessive mechanical stimuli also reduced the synthesis of superficial zone protein in chondrocytes, which exerts an important role in the protection of cartilage and bone layers from the degenerative changes. It is also revealed that various cytoskeletal changes induced by mechanical stimuli are transmitted through a stretch-activated or Ca2+ channel. Finally, on the basis of the results from a series of studies, it is demonstrated that optimal intra-articular environment can be achieved by splint therapy, if indicated, followed by occlusal reconstruction with orthodontic approach in patients with myalgia of the masticatory muscles, and TMJ internal derangement or anterior disk displacement with or without reduction. It is thus shown that orthodontic treatment is available for the treatment of TMDs and the long-term stability after treatment.

The main criterion for diagnosis of dysfunctional conditions of the temporomandibular joint is the visualization of the intra-articular cartilaginous disc. The method of diagnosis, that the most perfectly determines the disorders in the temporomandibular joint, particular the displacement of the menisci, is magnetic resonance imaging. So, the aim of the work was to determine the amplitude of anterior displacements of the menisci in patients suffering from dysfunction of the temporomandibular joint using magnetic resonance imaging. In 20 patients, who underwent magnetic resonance imaging, different amplitudes of the anterior displacements of the meniscus were determined. Patients were divided into groups. The first group included 6 patients who were diagnosed by MRI the anterior displacement of the disc to the center of the articular head. The second group included 4 patients who had anterior displacement of the disc to the center of the articular head by 2/3 of its own length. Ten patients of the third group had a displacement of the meniscus to the center of the articular head by 1/2 of its own length. For the future treatment of TMJ dysfunction, the distance of the pathological displacement of the meniscus determines the degree of occlusion. All patients were prescribed a Michigan-splint occlusal splint in combination with a sling-like head cap at night. The results of the selected treatment were interpreted after 3-6 months. A series of magnetic resonance imaging has described the articular fissures of the temporomandibular joint, articular discs (their shape in frontal projection and on parasagittal sections), posterior ligaments, and lateral pterygoid muscles. Each of the joints was carefully examined in the case when the mouth is closed and open. During the MRI description, the shape of the joint heads and their possible pathological changes were determined. In the position of the closed or open mouth, the positions of each of the discs and their poles relatively to the articular head in centimeters were compared, and the movement of the menisci was described. The sizes of disks of the closed and open mouth were defined. The study protocol also reported the shape and amplitude of the movements of the articular heads. Treatment was planned according to the selected protocol. For the first group of patients diagnosed with anterior meniscus dislocation, treatment was planned by separating the occlusion to the relatively physiological rest of the mandible (2 - 4 mm). The patients of the second group, in which anterior displacements of the disc relatively to the articular head by 2/3, were treated with detachment of the occlusion to contact with the cutting edge of the teeth of the upper and lower jaws. For the third patients’ group with diagnosed anterior displacement of the meniscus by 1/2, treatment was performed with a separation of the bite on 2 - 4 mm above the contact with the cutting edges of the front teeth. The main criterion for recovery is the complete disappearance of symptoms of dysfunction, even without the use of a splint. At the first stage of treatment the task was the following: reconstruction of a myotatic reflex by means of the medical and diagnostic occlusal splint "Michigan-splint" completed with the main slingshot cap. Patients were monitored monthly. The main problems were the following: after a week of using the structure the patients complained of increased salivation, muscle pain and burning, headache, which disappeared after approximately 3 weeks. The main cause of such phenomena is the physiological rearrangement of the muscular reflex, which involves a certain tension in the muscles and irritation of the nerve endings in the muscles due to changes in the usual occlusion. During planned examination, the patients demonstrated supercontacts followed by cap correction. In 3 or 6 months of using the Michigan-splint occlusal splint, patients noted a significant improvement and they didn’t have any complaints. The main criterion for recovery is the complete disappearance of symptoms of dysfunction, even without the use of a splint. Therefore, the next stage of treatment depended on the anatomical and functional changes of TMJ and consolidation of therapeutic effect was been necessary. Therefore, the use of magnetic resonance imaging of the temporomandibular joint to determine the amplitude of the displacements of the discs, ensures the effectiveness of the selected treatment. Prospects for further research include improvement of the MRI protocol and its correlation with definite symptoms, the distance of the vertical separation of occlusal surfaces, and the introduction of the protocol into practical health care.

AbstractTemporomandibular joint (TMJ) disorders can be painful and cause functional limitations and bone changes. Deeper clinical knowledge of the pathologies related to the TMJ has always been hindered by the difficult identification of the causes that limit its movement. Weight-bearing magnetic resonance imaging (WBMRI) can reproduce the articular movement in orthostasis and allows the evaluation of joint movement. WBMRI, compared with other procedures such as double-type condylography and real-time dynamic ultrasound, helps to better identify tissue characteristics of the articular glenoid-condylar surfaces, articular space, disk position on both the open and closed mouth, and the locoregional musculotendinous area. WBMRI also identifies the true position of the articular disk in orthostasis, emphasizing the different joint positions compared with the study carried out in a clinostatic (supine) position.

Abstract Objective: To determine the changes in articular disk position and the temporomandibular joint (TMJ) structure in patients who had an asymmetric setback of the mandible performed by a bilateral sagittal split ramus osteotomy with manual positioning of the condyle. Materials and Methods: Twenty-two patients with skeletal Class III malocclusion being treated at Nara Medical University Hospital were evaluated using clinical examination and pre- and postoperative magnetic resonance images of their TMJs. Results: Changes in articular disk position after asymmetric setback surgery were not statistically significant, although a tendency of anterior displacement in the fossa was noted. The anterior and posterior joint spaces did not show significant changes, whereas the condyle head of the deviated or contralateral side tended to be positioned downward. Conclusion: The asymmetric setback of the mandible with intraoperative manual positioning of the condyle does not significantly change the disk position in the fossa.

ABSTRACT Objective To evaluate and compare articular disk position, condylar position, and joint spaces in Class II vertical, Class II horizontal, and Class I cases. The purpose was to assess the potential for development of temporomandibular disorders (TMDs) in the three groups. Materials and Methods A sample of 75 cases, 25 cases in each group of Class I, Class II vertical, and Class II horizontal, were selected based on inclusion and exclusion criteria. Magnetic resonance imaging (MRI) assessments were made with a 1.5-Tesla basic system with a closed-mouth technique for evaluating articular disk position in the sagittal and transverse planes, condylar position, and joint spaces in the sagittal plane. Philips 3.0 software was used to analyze the MR images. Results There was evidence of alterations in the temporomandibular joint (TMJ) morphology in both Class II vertical and Class II horizontal cases, with maximum discrepancy in Class II vertical cases. MRI evaluation suggested a tendency for antero-medial disk displacement with anteriorly positioned condyles in Class II vertical cases. The discrepancy was milder in the Class II horizontal group. Conclusions Class II vertical cases are more susceptible to the development of TMDs and should be subjected to TMJ evaluation before starting any orthodontic treatment to intercept and prevent a mild asymptomatic TMD from developing into a more severe form. Class II vertical cases should be subjected to MRI evaluation before starting any orthodontic treatment.

This study quantified by, electrovibratography, the amount of mandible protrusion required to decrease significantly temporomandibular joint (TMJ) vibratory energy as an aid in the diagnosis of the recapture of anteriorly displaced disk. Eighteen patients diagnosed as having anterior disk displacement with reduction and TMJ clicking were submitted to electrovibratographic examination at the first appointment and treated with a stabilizing appliance and anterior positioning appliance with 1 to 5 mm protrusion. Vibratory energy was checked in each of these positions. Baseline data were used as control. At the first appointment, the patients had vibrations with more elevated intensities at the middle and late phases of the mouth opening cycle. At only one clinical step, mandible protrusion was obtained with the anterior repositioning appliance, ranging from 1 to 5 mm protusion. At each new position, a new electrovibratographic exam was made. After the 5-mm mandibular projection, only 2 patients presented vibration, with means between 0.6 and 2.8 Hz. Data were analyzed statistically by ANOVA and Tukey's test (alpha=0.05). The outcomes of this study indicate that 3 mm is the minimum amount of mandible protrusion to significantly decrease the TMJ vibratory energy and to recapture the displaced articular disk.

Purpose: Determination of the volume and sequence of radiation studies in the treatment of patients with displacement of the articular disc of the temporomandibular joint (TMJ)and myofascial pain disorders. Material and methods: The study included 48 patients with displacement of the articular disc of the TMJ and myofascial pain disorders. Clinical criteria for articular displacement were confirmed by MRI and CBCT. Studies of the function of the masticatory muscles were carried out at the Synapsis electromyograph. All patients underwent complex treatment, including relaxation of the masticatory muscles and relief of pain using injections of botulinum toxin in the actual masticatory, temporal and lateral pterygoid muscles (LPM), followed by repositioning split therapy. For the introduction of muscle relaxant in LPM, we have developed and applied external periarticular injection access to LPM. The method is based on reaching the zone of joint attachment of the upper and lower heads of the LPM with MRI navigation. Surveillance continued for up to 12 months with MRI monitoring of the position of the articular disc. Results: The stages of treatment of SJS of the TMJ with control use of MRI and CT, as well as a method for the administration of botulinum toxin under MRI navigation, have been developed. The first stage included CT and MRI of the temporomandibular joint, the second stage – injections of botulinum toxin into the masticatory muscles using the developed periarticular access to the LPM with MRI navigation, as well as CBCT with a splint to control the new (established) position of the lower jaw; the third and fourth stages included continuation of the reduction splint therapy, correction of the splint, observation for 3-6 months with control CBCT after 6 months to assess the position of the mandible without splint. Achieved an increase in the posterior and upper temporomandibular joint distances and the correct position of the lower jaw. Conclusion: Performing radiation studies on time at certain stages of treatment, differing in their content and volume, provided a complete diagnosis, planning treatment measures and monitoring the results.

O objetivo do trabalho consiste em avaliar a relação entre o posicionamento dos discos articulares durante a dinâmica dos movimentos mandibulares e o levantamento dos dados clínicos com especial ênfase à dor e sua localização preferencial em um grupo de 74 pacientes sintomáticos sendo 51 do gênero feminino e 23 do gênero masculino, entre 19 a 78 anos de idade, portadores de manifestações compatíveis à processos de degeneração interna das articulações temporomandibulares e as correspondentes imagens por meio de imagens em ressonância magnética em norma sagital. As imagens foram adquiridas com a utilização de aparelho com potência de campo magnético de 1.5 Tesla e bobina de superfície dupla para captação de sinais, segundo protocolo indicado para aquisição multiplanar, com ênfase na série definada como densidade de prótons (DP), que foram posteriormente manipuladas numa estação de imagem independenteworkstation - de alta resolução utilizando-se ferramentas eletrônicas em 4 situações de amplitude de abertura bucal (repouso, 10mm; 20mm; 30mm) para ambos os lados. As análises foram realizadas por dois observadores em tempos distintos e transferidas para tabelas de identificação para elaboração das análises estatísticas. Objetivou-se destacar a importância deste método de imagem como base para o diagnóstico de distúrbios destas articulações, pois em muitas situações as informações clínicas obtidas durante a anamnese não foram ao encontro dos dados imaginológicos. Os dados obtidos foram dispostos em tabelas e gráficos os quais permitiram concluir que não houve vínculo entre os fenômenos de dor e a topografia dos discos e observou-se carência de vínculo dos fenômenos de dor localizada com a correspondente morfologia dos discos.
The objective is to assess the relationship between the positioning of articular discs during the dynamics of the mandibular movements and the lifting of the clinical data with particular emphasis on pain and its location preference in a group of 74 symptomatic patients, 51 females and 23 male, between 19 to 78 years. Pacients presents events aliable with internal degeneration processes of temporomandibular joints and related images through a standard sagittal MRI. The images were acquired with the use of apparatus with power magnetic field of 1.5 Tesla and double surface coil to signals capture, according protocol set out to purchase multiplanar aquirer, with emphasis on the series defined as density of protons (PD), which were then handled at a high resolution self-image workstation - using the electronic tools in 4 cases of oral extent of openness (rest, 10mm, 20mm, 30mm) for both sides. The analyses were performed by two observers at different times and transferred to identification tables focusing statistical analyses. The aim was to highlight the importance of this method of image as a basis for the diagnosis of these joints disorders, because in many cases the information obtained during the clinical history does not meet the imaging data. The data were arranged in tables and graphs which showed that there was no link between the phenomena of pain and topography of the disks and there was lack of linkage of the phenomena of pain located with the corresponding morphology of the disks.