Open-mouth Position Research Articles

Functional magnetic resonance imaging of temporomandibular joint disorders.

Fifty-eight temporomandibular joints (TMJs) from 40 patients with TMJ-related symptoms were examined by means of magnetic resonance scans with modified gradient echo sequences and a special double coil. This technique yielded a good spatial resolution of the intra-articular soft tissues, especially the articular disc and the bone structure of the TMJ. In combination with an incremental jaw opener, the disc-condyle complex was analysed in various closed and open mouth positions, depending on the clinical examination. Open mouth movement with differentiation of disc-condyle rotational and translation movement was demonstrated. Disturbances of TMJ motion showed interrupted condylar translation combined with mandibular deviation during open mouth movement (n = 8/58). Early phases of internal derangement of the TMJ with partial anterior disc displacement with (n = 12/58) or without (n = 2/58) reduction, total anterior disc displacement without reduction (n = 10/58), disc deformation (n = 10/58), disc adhesion (n = 2/58), condylar hypermobility (n = 6/58), condylar displacement (n = 8/58), and late phases of internal derangement of the TMJ with osteoarthrosis (n = 14/58) were clearly identified. Bilateral TMJ disorder was found in 72.5 per cent of the patients. By using motion-adapted, semi-dynamic magnetic resonance imaging (MRI), it is possible to improve the understanding of the complexity of TMJ movements.

Detectability of anterior displacement of the articular disk in the temporomandibular joint on helical computed tomographyThe value of open mouth position

Objective. The purpose of this study was to establish the diagnostic reliability of anterior displacement of the articular disk in the temporomandibular joint on helical computed tomography. Study design. Ninety-four consecutive patients were examined through use of both computed tomography and magnetic resonance imaging. On axial computed tomography, anterior disk displacement was defined as the presence of an area of soft tissue density that was semilunar in shape and located in front of the mandibular condyle. Results. With magnetic resonance imaging taken as the diagnostic gold standard in evaluation of articular disk position, the sensitivity, specificity, and accuracy for computed tomography were 91%, 100%, and 97%, respectively, in the closed mouth position and 96%, 99%, and 98%, respectively, in the open mouth position. Conclusions. The detectability on axial helical computed tomography of anterior displacement of the articular disk in the temporomandibular joint in the open mouth position was almost equal to that on magnetic resonance imaging. It is recommended that the open mouth position be added when helical computed tomography is used to evaluate patients with temporomandibular joint disease. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;88: 106-11)

顎関節症における関節円板のＭＲＩによる検討 関節円板の前方転位の程度と復位および臨床所見との関係

To determine the position of the anteriorly displaced articular disc, we examined temporomandibular joints by magnetic resonance imaging (MRI) in 54 patients with unilateral temporomandibular joint dysfunction. MRI was done before conservative therapy in the occlusal and maximal open-mouth position. We drew a straight line connecting the lowest point of the articular eminence (point A) and the highest point of the external acoustic pore (point E) by tracing the sagittal view on MRI. On the standard A-E line, points B', C', and D' were sought by dropping perpendicular lines from the deepest point of the glenoid fossa (point B), the highest point of the condylar head (point C), and the most posterior point of the articular disc (point D). We then determined the sagittal position of the articular disc in the glenoid fossa by measuring the distances AD' and C'D' and sought the correlation between these distances and clinical findings. The results were as follows. 1. The distance AD' in 33 patients with MRI-defined irreversible displacement of the disc was shorter than that in 10 patients with reversible displacement (3.7±1.9mm vs 6.8±2.0mm, p<0.0001). In contrast, the distance C'D' in the former was longer than that in the latter (6.0±1.7mm vs 3.4±1.5mm, P<0.0001). Of 29 discs displaced anteriorly less than 5 mm in distance C'D', 19 (66%) had reversible or no displacement. However, 23 (92%) of 25 discs displaced more than 5 mm in distance C'D' had irreversible displacement. 2. Disc deformity and abnormal signal intensity bands in the condylar head closely correlated with distances AD' and C'D'. In 17 patients without disc deformity, mean AD' and C'D' distances were 9.8± 2.7mm and 0.2± 2.8mm, respectively. In 19 and 18 patients with mild to moderate and severe deformity, the mean AD'(C'D') distances were 5.4±1.8mm (4.5±1.6mm) and 2.7±1.8mm (6.8±1.5mm), respectively. 3. Although distance AD' and C'D' did not correlate with clinical symptoms, the degree of anterior disc displacement correlated with the therapeutic effect of conservative therapy. The mean AD' distance (7.3±3.7mm) in 15 patients with a complete response to conservative therapy was longer than that (3.4±1.4mm) in 5 patients with no improvement. These results indicate that the sagittal position of the articular disc can be determined by MRI and that successful conservative therapy is unlikely if anterior disc displacement extends beyond 5 mm from the top of the condylar head, often resulting in irreversible displacement.

Gas in the temporomandibular joint: computed tomography findings: Report of 3 cases

In each of 3 patients referred for computed tomographic examinations of the temporomandibular joint, a gas collection was observed in the inferior space of the joint. The gas was observed on the posterosuperior surface of the mandibular condyle in the open mouth position in each patient. Each of 2 patients had saucer-shaped bone resorption of the mandibular condyle adjacent to the gas; 1 patient had no remarkable bone abnormality. A history of temporomandibular joint puncture or facial trauma was denied by all 3 patients.

The validity of clinical examination for diagnosing anterior disk displacement without reduction

Objective. The objective of this study was to evaluate the diagnostic accuracy of patient history and clinical signs as confirmed by magnetic resonance imaging examination for diagnosing anterior disk displacement without reduction. Study Design. A series of 273 consecutive patients with temporomandibular disorders were clinically examined according to well-defined criteria. Patients were first asked if they had a history of clicking. The following clinical characteristics of anterior disk displacement without reduction were then assessed: (1) maximal mouth opening less than 40 mm; (2) deflection of the mandible to the affected side at the maximal mouth opening position; (3) limitation of condylar translation on palpation during maximal mouth opening; (4) preauricular pain during mandibular movements; and (5) crepitation. Bilateral magnetic resonance images were obtained for all patients, and the magnetic resonance imaging interpretation was compared with the clinical examination findings to assess the diagnostic accuracy of the clinical findings. Results. The sensitivity was considerably low in contrast with the relatively high specificity for all six clinical parameters tested. The overall accuracies of the clinical parameters ranged from 71% to 81%. Conclusion. Our results suggest that the predictability of historical or clinical findings to differentiate anterior disk displacement without reduction from other diagnoses is not high.

Radiographic Assessment and Reliability Study of the Craniovertebral Sidebending Test

Background and Purpose: In orthopaedic manual physical therapy, passive intervertebral joint testing of the upper cervical spine is widely used for clinical assessment. However, the test position has not been standardized and tester reliability has not been well established. The purpose of this study is to determine whether patient positioning affects the degree of reliability of passive motion testing and end-feel assessment when passively testing craniovertebral sidebending.Subjects: Ten subjects participated in both the radiographic and clinical assessment portion of this study with mean age of 32.5 +/− 6.9 years.Methods: Open-mouth position radiographs were used to measure passive craniovertebral sidebending at the “erect” neutral and the “physiological” neutral positions. Intertester and intratester reliability were determined on the same group of subjects using six physical therapists to assess end-feel and mobility grades for passive craniovertebral sidebending in five positions.Results: The mean total sidebending motion for C0C2 was 8.3 degrees for the physiological neutral position and 7.2 degrees for the erect neutral position. In the clinical assessment portion of the study, Kappa scores ranged from − .027 to .182 for intertester reliability and from − .022 to .137 for intratester reliability for mobility grade assessment with minimal difference noted between the five test positions. For end-feel assessment, the Kappa scores ranged from − .043 to .119 for intertester reliability and from .01 to .308 for intratester reliability with the physiological neutral position demonstrating the highest intratester reliability.Conclusion and Discussion: The results of the radiographic assessment portion of this study demonstrate greater passive range of motion in the physiological neutral position for the majority of the subjects offering some support for the use of the physiological neutral position as the standard position of the cervical spine for testing passive craniovertebral sidebending motion. However, all the test positions showed poor intertester reliability for the craniovertebral sidebending passive motion test. Follow-up studies are needed that allow testers an opportunity to correlate clinical findings with the passive craniovertebral motion test in order to establish reliability in using this manual assessment procedure.

MRI of the TMJ disc with intravenous administration of gadopentetate dimeglumine.

The purpose of this study was to ascertain whether MR imaging with intravenous administration of gadopenetate dimeglumine (Gd-DTPA) is useful in the demonstration of the temporomandibular joint (TMJ) disc. Sagittal T1-weighted MR images of 50 TMJs (25 patients) were obtained using a 0.5-T system both before and after intravenous injection of Gd-DTPA. The authors depicted the TMJ in which intravenous injection of Gd-DTPA improved visulization of the disc. Intravenous injection of Gd-DTPA increased intensity in the retrodiscal space, the pterygoid venous plexus, as well as joint effusion by diffused Gd-DTPA. The technique improved visualization of 10 (50%) of 20 normal discs and 20 (67%) of 30 anterior disc displacements in closed-mouth position, and also 23 (74%) of 31 normal discs and 12 (63%) of 19 anterior disc displacements in open-mouth position. There were 12 TMJs (24% of the 50 TMJs) in which equivocal findings became highly diagnostic. The incidence in marked contrast effect was higher in TMJs with severe internal derangement than in those with normal or mild internal derangement (p < 0.005). Using a 0.5-T MR imager, T1-weighted imaging with intravenous injection of Gd-DTPA showed more anatomic details than imaging without the contrast agent.

Diagnostic potential of pseudo-dynamic MRI (CINE mode) for evaluation of internal derangement of the TMJ

In addition to the patient's history and a thorough clinical investigation, magnetic resonance imaging (MRI) of the temporomandibular joint (TMJ) has been introduced to complete the findings for the diagnosis of internal derangement of the TMJ. However, ‘dynamic information’ is desirable to help us to understand the mechanism of internal derangement. This information is given for example by electronic axiography recording systems. The lack of any ability to assess joint function dynamically in MRI is a point of criticism. Using a computer-driven pseudodynamic MRI system (CINE-mode) ‘dynamic information’ should be now available. In this investigation 21 patients with TMJ disorders were examined using both conventional static MRI and CINE mode. For the diagnosis of an anterior displaced disc with or without reduction in 18 cases (86%) it was only necessary to consider two static MRIs: a closed mouth position and a maximal open mouth position. Comparison showed there was no advantage in using CINE mode. Contrast and resolution of the static MRIs were shown to be better and so additional findings such as joint effusion and disc deformation could be diagnosed on static MRIs with greater certainty. Only in three (14%) cases was the dynamic information from CINE mode useful for the diagnosis of the displacement of the disc.

Intracranial reduction of an intact mandibular condyle displaced into the middle cranial fossa

Although displacement of the condyle intracranially is a relatively rare event, 1 this type of injury should be suspected when there is a history of the following : 1) severe trauma to the chin ; 2) limitation of opening ; 3) inability to close into occlusion ; 4) deviation of the chin toward the side of the suspected injury ; 5) occlusion only on the side of the suspected injury ; 6) cerebrospinal fluid (CSF) leak from the ear of the involved side ; 7) difficulty in interpreting condylar position on plain radiographs.6 The rarity of this injury, compared with subcondylar fractures, is related to the anatomy of the condylar neck, which is relatively weak compared with the rather dense posterior slope of the mandibular fossa. 2 Predisposing factors include : a thin condylar neck, 3 increased pneumatization of the temporal bone, lack of posterior teeth, or an open mouth position on impact. 4,5 Neurologic signs such as loss of consciousness, nausea, evidence of CSF leak, paresis of facial muscles, or deafness may indicate intracranial violation with resultant injury or edema. 6 Because of fibers from the inferior retina passing along the geniculocalcarine tract (Meyer's loop) within the temporal lobe, a contralateral superior quadrantanopsia may ensue. Damage to vascular structures may cause a temporal lobe hematoma, resulting in clinical symptoms of lethargy, restlessness, or combativeness soon after the initial injury. Within a few hours of the formation of the hepatoma, focal neurologic signs may develop. These usually begin with weakness in the face and progress to hemiparesis by about the third day. Pupillary dilitation occurs late in the clinical course of an expanding hematoma. 7 It is recommended that patients undergo a computed tomography (CT) scan of the head and a neurosurgical consult be obtained in a case when there is clinical suspicion of intracranial injury.

Magnetic resonance imaging of the temporomandibular joint Value of pseudodynamic images

Magnetic resonance fast scanning technique (gradient recalled acquisition at steady state) has been reported to be useful when evaluating the dynamics of the temporomandibular joint and also to be accurate for determining the disk position. Yet in our clinical experience gradient recalled acquisition at steady state images have frequently been inferior to proton density images for diagnosis of temporomandibular joint internal derangement. The first aim of this study was to compare gradient recalled acquisition at steady state images with proton density images for diagnosis of disk position. The second aim was to identify what additional information could be gathered from gradient recalled acquisition at steady state images when compared with static proton density images. We obtained unilateral images from 20 patients with signs and symptoms of temporomandibular joint internal derangement and from 20 asymptomatic volunteers. Multiple gradient recalled acquisition at steady state images were obtained during mouth opening and closing and proton density images were obtained at the closed and open mouth positions. The results showed that the gradient recalled acquisition at steady state images were in accordance with the proton density images in 32 joints (80%) and were false negative in 8 joints (20%). Six of the joints with false-negative gradient recalled acquisition at steady state images showed sideways disk displacement, and two showed partial anterior disk displacement. Gradient recalled acquisition at steady state images, on the other hand, provided information about movement pattern and also demonstrated impingement of the joint structures on the muscles anterior to the joint at maximal mouth opening. It was concluded that gradient recalled acquisition at steady state images cannot replace proton density images for diagnosis of disk position but they can provide supplementary information for evaluation of joint function.

顎関節内障クローズドロックに対する保存療法のＭＲＩによる評価

This study used 1.5 Tesla magnetic resonance imaging (MRI) to evaluate the positional and morphological changes of the disc and condyle in patients with closed lock treated nonsurgically. A total of 20 joints (19 patients) which were successfully unlocked by nonsurgical treatment were studied. Nonsurgical treatment was gradually applied a fbllows: 1. mandibular manipulation, 2. anterior splint assisted manipulation, 3. pumping manipulation, 4. stabilization splint therapy. The joints were evaluated by MRI in the closed-and open-mouth positions before and after treatment. Posttreatment MRI was also performed with the splint in place. Each imaging procedure was made in the same sagittal plane.After treatment, 19 patients experienced significant improvement in pain, range of motion, and mandibular dysfunction. Post-treatment MRI revealed that only one joint was normal. Six joints had anterior disc displacement with reduction (DWR), and 13 joints had anterior disc displacement without reduction (DNR). Evidence of disc repositioning with the splint in place was seen in 4 joints in the DWR group. Disc mobility increased with improved condylar translation in 19 joints. Disc deformity progressed in 10 joints of the DNR group.These results suggest that successful treatment for internal derangement with closed lock may require an increase in the mobility of the disc, regardless of disc position.

Magnetic resonance evaluation of the temporomandibular joint disc position and configuration.

Although magnetic resonance imaging (MRI) is the modality of choice for evaluation of TMJ disc position, it is sometimes difficult to determine when it is displaced or reduced. The MR images of 273 Patients with a clinical diagnosis of TMJ disorders were assessed for disc position and configuration. Most (90-97%) of the slightly anteriorly displaced discs were reduced to the normal position in the open-mouth position. However, the greater part (76%) of the distorted discs was completely displaced anteriorly and without reduction. Since no distorted discs were found in the normal disc position, we conclude that discs are distorted after displacement.

Clinical symptoms of open lock position of the condyle: Relation to anterior dislocation of the temporomandibular joint

Nine cases of open lock position of the condyle of the temporomandibular joint (TMJ) are reported. In two patients recurrent dislocation of the TMJ was diagnosed clinically, and four had previous episodes of anterior dislocation. An arthrotomographic examination revealed that the condyles of the affected TMJs were located anterior to the anterior bands of the disks at an open-mouth position. An arthrographic fluoroscopic examination showed that the anterior bands mechanically obstructed the anteriorly displaced condyles from posterior movement into the articular fossae to various degrees at open-mouth position. One cause of anterior dislocation of the TMJ is thought to be fixation of the condyle in the open lock position resulting from a disturbance of a neuromuscular mechanism. In the two patients with dislocation, occlusal treatment eliminated muscular symptoms and the dislocations completely disappeared.

Incremental hydraulic jaw opener for MR imaging of the temporomandibular joint.

Magnetic resonance (MR) imaging in the open- and closed-mouth positions is the method of choice for visualizing the temporomandibular joint (TMJ). To analyze the TMJ in response to various degrees of mouth opening, the authors constructed a hydraulic incremental jaw opener. This apparatus enables obtaining of reproducible and stable positions of TMJ articulation. With modified gradient pulse sequences, the technique yields good spatial resolution of joint anatomy, including that of the articular disk. The application of a cine program allows cinematographic display of TMJ motion, which in conjunction with static open- and closed-mouth views can be useful in the diagnosis of TMJ dysfunction. The authors used the incremental jaw opener to examine the disk-condyle complex at each open-mouth position, with particular attention to extreme open-mouth positions.

A standardized method of X-ray CT for sagittal splitting osteotomy of the mandibular ramus

A useful standardized method of X-ray computed tomography (CT) was proposed for the preoperative examination of sagittal splitting osteotomy of the mandibular ramus. In our assessment conducted for cases of mandibular prognathism operated on by a modified technique, the most informative CT image of the mandibular ramus was provided by the scans between the upper and lower dentitions in the open mouth position at which the scan-plane angulation was given as parallel to the dentition in each jaw. These sections enabled preoperative assessment on the mesio-lateral thickness of the marrow space and the positional relationship between the ramal cortices and the mandibular canal together with other geography of the ramal bone structure. Using these CT images, the plane of sagittal osteotomy is predictable. A technique for obtaining standardized CT slice is proposed in this report.

Findings of mandibular movement and the position of the mandibular condyles during maximal mouth opening

An investigation with respect to position of the mandibular condyles in relation to maximal vertical mouth opening was undertaken. For this purpose, 51 subjects of different nationalities were examined. None of the 51 persons had a TMJ disorder. The mobility of the mandible in different directions was clinically measured. With the use of two different reference lines (Methods A and B), the amount of the movement of the condyle from closed to maximal mouth opening position was measured in the sagittal plane on lateral tomograms. All of the measurements were recorded, and the means, SD, and range of variation were calculated. Statistical analysis was subsequently performed. The clinical results are comparable to those of other previous clinical studies. As seen in the lateral tomograms, the condyle in 41 out of 51 subjects moved beyond the articular eminence during maximal mouth opening. It was occasionally situated higher than the eminence. In only ten subjects, the condyle reached only the top of the articular eminence during maximal mouth opening. A moderate degree of dependency and correlation was found between maximal vertical movement of the mandible and the amount of movement of the right and left condyles from closed to maximal open position of the mouth, as seen in tomograms. None of our subjects had any sign of luxation despite the position of the condyle beyond the articular eminence with maximal mouth opening. Therefore, the diagnosis of condylar luxation cannot be established by radiologic investigation alone.

Three-dimensional computed tomographic analysis of the normal temporomandibular joint

Ten temporomandibular joints, obtained from three asymptomatic patients and two cadavers, were examined by three-dimensional computed tomography. The osseous components of the condylar process of the mandible and the glenoid fossa of the temporal bone were well visualized. The meniscus was visualized in both the closed- and the open-mouth positions. Advantages and disadvantages of the technique are discussed.

A method of localisation and fixation for mid-facial osteotomies

A preliminary report on a method of localisation and fixation for mid-facial osteotomies is described. The method depends on the localisation of the mandible in a predetermined open-mouth position, so allowing surgery to be performed with an oral tube. The method offers advantages in terms of surgical safety and accuracy. It is theoretically applicable to a wider range of osteotomies than the Le Fort II procedure described here.

The Differential Diagnosis of Traumatic Lesions of the Spine

My part in this symposium is to discuss certain aspects of the roentgenology of the spine. This paper will not consider fractures or dislocations but rather conditions of the spine not due to an individual trauma, which, nevertheless, may be mistaken for the results of an injury. Non-traumatic dislocation at the atlanto-axial joint is a definite entity (4). This condition occurs in young people and usually accompanies an infection in the throat and in the cervical lymph nodes. It may be present in the course of a rheumatic fever. It occurs in the absence of trauma. Because of the torticollis present, it may be difficult to get satisfactory roentgenograms. The dislocation is a rotatory one and may be hard to demonstrate by the usual open-mouth position for this region. Laminagraphs are often of considerable help. Englander (11) recommends the basal view of the skull in order to show the relation between the atlas and axis. In most of these cases there is a definite separation between the posterior surface ...