Temporomandibular Joint

The mobility of the mandible is usually measured interincisally with a millimeter ruler and is known as maximal mouth opening (1±6). Changes in maximal mouth opening may reflect the impact of temporomandibular disorders as well as the therapeutic success of an intervention (7). ...

A 51-year-old woman was referred to us with the chief complaint of swelling and pain in the left preauricular region of 3 months' duration. Computed tomography showed a hypodense ovoid lesion causing erosion of the lateral aspect of the left condyle (Fig. 1). Fine-needle ...

To assess and evaluate morpho-structural alterations of the retrodiscal tissue of the temporomandibular joint (TMJ) that may be seen in chronic trauma of the condylo-meniscal incoordination through magnetic resonance (MR), using T2-weighted TSE sequences. The study included 40 patients, 6 male and 34 female, age range 12-66 years, mean age 28.5 years. According to the Wilkes classification, TMJs of patients were graded as follows: 10 grade 1 TMJs; 28 grade 2, 16 grade 3, and 26 grade 4. Scans were obtained with a 1.5 T MRI unit, and a dedicated surface coil, using T2-weighted TSE sequences (TR 3000-3500, TE 90-100), 2 acquisitions, 256x256 matrix, 3-mm section thickness, with a 0-mm interval, and 2'30" duration for a single acquisition. Scans were obtained both during opening and during closure of the mouth, on 3 planes: sagittal oblique, perpendicular to the condylar long axis; coronal oblique, perpendicular to the anteroposterior axis of the discs; and axial, perpendicula...

Prospective evaluation by magnetic resonance imaging (MRI) and both single photon emission computed tomography (SPECT) and planar bone scintigraphy was undertaken in 31 temporomandibular joints (TMJs) of 21 symptomatic patients. When compared with the results of subsequent arthrography, MRI (0.88) was more sensitive than SPECT (0.76) or planar (0.56) scintigraphy for detection of internal derangement of the TMJ. A diagnostic sensitivity of 0.96 was achieved when the results of either MRI or SPECT was considered evidence of internal joint derangement. Five symptomatic TMJs, clinically thought to be abnormal, were positive on SPECT but showed no evidence of anterior disk displacement at the time of arthrography. In such instances, SPECT may be detecting functionally significant altered joint mechanics that are not evident on anatomic imaging of the TMJ.

Although the majority of teleost fishes possess a fused lower jaw (or mandible), some lineages have acquired a secondary joint in the lower jaw, termed the intramandibular joint (IMJ). The IMJ is a new module that formed within the already exceptionally complex teleost head, and disarticulation of two bony elements of the mandible potentially creates a "double-jointed" jaw. The apparent independent acquisition of this new functional module in divergent lineages raises a suite of questions. (1) How many teleostean lineages contain IMJ-bearing species? (2) Does the IMJ serve the same purpose in all teleosts? (3) Is the IMJ associated with altered feeding kinematics? (4) Do IMJ-bearing fishes experience trade-offs in other aspects of feeding performance? (5) Is the IMJ used to procure prey that are otherwise unavailable? The IMJ is probably under-reported, but has been documented in at least 10 lineages within the Teleostei. Across diverse IMJ-bearing lineages, this secondary...

The aims of this longitudinal study were to perform a comprehensive clinical evaluation of temporomandibular joint (TMJ) and to investigate the association between the clinical and magnetic resonance imaging (MRI) findings in the TMJs of patients with juvenile idiopathic arthritis (JIA). Seventy-five patients with JIA participated in this study. All patients underwent a rheumatological examination performed by a paediatric rheumatologist, a TMJ examination performed by a single dentist and an MRI with contrast of the TMJs. These examinations were scheduled on the same date. The patients were examined again 1 year later. Twenty-eight (37.3 %) patients reported symptoms at the first evaluation and 11 (14.7 %) patients at the second evaluation. In relation to signs, 35 (46.7 %) of the patients presented at least one sign at the first evaluation and 29 (38.7 %) at the second. Intense contrast enhancement of TMJ was significantly associated with disease activity (p < 0.001) at the fir...

In a 4-year period, 40 compact aluminum oxide ceramic implants fixed with titanium plates and screws were used: 24 for the correction of mandibular defects, 9 for temporomandibular joint replacement, and 7 for augmentation of facial contour. During the 1 to 4 years following the operations, it was not necessary to remove any aluminum oxide joint or implant used for contour correction. In 5 of the 24 cases of mandibular reconstruction, however, it was necessary to remove the ceramic. In 3 cases, this was due to recurrence of the tumor, and in 2 cases the cause was dermal necrosis.

Centric relation (CR) has been considered a maxillomandibular position of choice for some dental and prosthetic procedures. Although regarded as a fully reproducible relation, there is great controversy about its clinical use and recording technique, especially in patients with signs and symptoms of temporomandibular disorders (TMD). This study aimed at evaluating the effectiveness of a training program on intra- and interexaminer agreement when determining the clinical record of the CR position. Forty individuals constituted the sample, divided into symptomatic (TMD) and asymptomatic groups. Three previously calibrated examiners performed the initial assessment and the second evaluation after 30 days in a blind design, using Dawson s bilateral manipulation technique with and without an anterior stop. The amount of frontal and sagittal deviations in relation to intercuspal position, the presence of pain and discomfort during manipulation, and the first occlusal contact in CR were an...

The aim of this study was to develop a three-dimensional finite element model of the mandible, including its TMJ. The model consisted of 7942 nodes and 41,010 elements, which were obtained from a convergence test, done to minimize the result error. It included cancellous and cortical bone, periodontal ligament, masticatory muscles (masseters, temporalis, lateral and internal pterygoids), teeth and the articular disk. All characteristics such as dental, mandibular, and muscle geometry were obtained from a computerized tomography (CT) of a living person. CT sections were scanned and digitized with a CAD software program. After images were adequately assembled, a vertical tracing was done which allowed the definition of a three-dimensional mesh. Modeling of teeth was carried out independently and the periodontal ligament was later included, limiting the alveolar area. Muscles were modeled based on flat-scale photographs and total muscle force was distributed in multiple vectors. The ar...

A nonfluoroscopic temporomandibular joint arthrographic technique is contrasted with a more widely employed fluoroscopically guided technique. The nonfluoroscopic technique uses a posterior approach to joint injection, as contrasted with the lateral injection approach of the fluoroscopically guided technique. The advantages of the nonfluoroscopic technique are less radiation dose to the patient, less expensive and less sophisticated imaging equipment, and less potential for neurovascular trauma. The fluoroscopic technique offers greater control of the procedure, less patient and operator time, and the capability for a dynamic videofluoroscopic study. Both techniques appear to be safe and efficacious. Differences in anatomy, imaging modalities, patient radiation exposure, and potential complications are also discussed as part of this comparison.

BAOMS has requested that guidelines be formulated for the replacement of the temporomandibular joint (TMJ). This is an expensive and technique sensitive method of TMJ reconstruction and in the current climate warrants an agreed approach. The following document states the indications and contraindications for this technique as discussed and agreed amongst surgeons currently carrying out this procedure in the UK.

 An exceptional case of a duplicate Meckel’s cartilage in a human fetus, with a C-R length of 57 mm, is studied. Another small cartilage, isolated from Meckel’s, of rounded morphology, was observed in a small region between the temporomandibular joint and the middle ear. This cartilage was only present on the right side.

Transcranial radiographs are frequently used to assess condyle-fossa relationships. However, their validity in representing condyle position has been questioned. Intermethod comparisons were performed between methods assessing condyle position by subjective evaluation and by linear and area measurement of the interarticular space. Linear measurement of the subjective closest anterior and posterior interarticular space and subjective evaluation were the mutually preferred methods in both transcranial radiographs and tomograms. Statistically significant correlations were shown (p less than 0.05) for condyle position between pairs of clinical transcranial radiographs and linear tomograms of the same temporomandibular joints. However there was a qualitative concordance in assessed posterior concentric and anterior positions in only 80% of the pairs, and a full concordance in the degree of condylar displacement was found in only 60% of the cases. Although still clinically helpful, the us...

This article studied the relationship among respiratory, masticatory and cervical muscles and the factors that contribute for TMD. It consists in a review of studies approaching dysfunctional breathing and TMD, enclosing mouth breathing syndrome, anxiety, respiratory mechanics changes, diaphragmatic muscular dystonia and overuse of accessory inspiratory muscles. It also stresses the importance of breathing evaluation and the multiprofessional intervention in

To evaluate the use of preoperative computed tomographic angiography (CTA) and selective embolization as an ancillary tool for the treatment of patients with temporomandibular joint (TMJ) ankylosis. The present study was a case series of subjects with bilateral TMJ ankylosis who had undergone preoperative CTA and surgical release with immediate reconstruction. The indications for CTA were either an intimate association between the vessels and the ankylotic mass on the facial computed tomography (CT) scan or a history of multiple previous TMJ operations. In cases in which intimate anatomic association was present between the branches of the maxillary artery and the ankylotic masses, preoperative selective embolization was performed. All subjects underwent a standard approach to ankylosis release with immediate reconstruction and were followed up for up to 6 months postoperatively. The demographic and operative variables were recorded for each subject. Five subjects (mean age, 36.4 years; 3 females) with bilateral TMJ ankylosis underwent release and had undergone preoperative CTA for vascular assessment. Three subjects underwent preoperative embolization. The total operating time ranged from 5.9 to 10.3 hours. The intraoperative blood loss ranged from 150 to 3,750 mL. One patient who had undergone unilateral embolization required an intraoperative transfusion because of bleeding on the nonembolized side. No adverse cardiac, renal, or neurologic events developed secondary to the blood loss. In all 5 subjects, the preoperative maximal incisor opening was less than 15 mm, increased to more than 35 mm intraoperatively, and was 30 mm or more at 6 months or longer of follow-up. In select cases, CTA can be a useful adjunct in the treatment of patients with TMJ ankylosis.

Accuracy of techniques for recording the orientation of the maxillary arch to the articulation of the temporomandibular joints has been reported. The variability contributed by the dentist and the equipment within a technique may also contribute to technical error. This study investigated the variability of a group of dentists who used an arbitrary ear-face-bow instrument to mount a maxillary cast. The same maxillary cast on a single experimental subject was mounted on an articulator with a common arbitrary ear-face-bow instrument. This cast was equipped with 4 reference points for the measurement of changes of spatial orientation of the cast, which were determined through coordinate measurements with a machinist's microscope. A repeated measures analysis of variance was used to determine statistically significant changes in spatial orientation with a Wilks' Lambda test to compare mean values. A confidence interval of 95% demonstrated that any dentist might expect a range of...

Temporomandibular joint (TMJ) dysfunction is a common condition that is best evaluated with magnetic resonance (MR) imaging. The first step in MR imaging of the TMJ is to evaluate the articular disk, or meniscus, in terms of its morphologic features and its location relative to the condyle in both closed- and open-mouth positions. Disk location is of prime importance because the presence of a displaced disk is a critical sign of TMJ dysfunction. However, disk displacement is also frequently seen in asymptomatic volunteers, so that other findings may be required to help make the diagnosis. These findings include thickening of an attachment of the lateral pterygoid muscle, rupture of retrodiskal layers, and joint effusion and can serve as indirect early signs of TMJ dysfunction. It is important for the radiologist to detect early MR imaging signs of dysfunction, thereby avoiding the evolution of this condition to its final stage, an advanced and irreversible phase that is characterize...