Normal Temporomandibular Joint Research Articles

The effects of TMJ symptoms on skeletal morphology in orthodontic patients with TMJ disc displacement

Objective. The aim of this study was to investigate the effects of temporomandibular joint (TMJ) symptoms on skeletal morphologies of orthodontic patients with TMJ disc displacement (DD). Materials and methods. The sample consisted of 197 women seeking orthodontic treatment. The subjects were divided into two groups according to the presence of TMJ symptoms: the presence and absence of TMJ symptoms. Each group was sub-divided into three groups based on magnetic resonance images of bilateral TMJs: bilateral normal disc position (BN), bilateral disc displacement with reduction (DDR) and bilateral disc displacement without reduction (DDNR). Seventeen variables from lateral cephalograms were analyzed by two-way analysis of variance to identify differences in skeletal morphologies with respect to TMJ symptoms and TMJ DD status. Results. Patients with TMJ DD were more likely to have short ramus height, short mandibular body length and backward positioning of the ramus and mandible. These skeletal morphologies became more severe as TMJ DD progressed to DDNR. However, the skeletal morphologies associated with TMJ DD were not significantly different between symptomatic and asymptomatic patients. As a result, patients with TMJ DD had backward positioning and clockwise rotation compared to those with bilateral normal TMJs, irrespective of the presence of TMJ symptom. Conclusions. This study suggests that TMJ DD is associated with altered skeletal morphology, but TMJ symptoms do not significantly influence the relationships between TMJ DD and skeletal morphology.

Chewing movements altered in the presence of temporomandibular joint internal derangements

Aims:The objectives were to find specific factors that are mathematically distinct between the chewing timings, movement pattern shapes, variability, and movement velocities of: (1) normal asymptomatic subjects and (2) a group of subjects with verified temporomandibular joint (TMJ) internal derangements.Methodology:Left- and right-sided chewing movement recordings of 28 subjects (34·5±14·0 years) were randomly selected from a large database of patients exhibiting verified unilateral or bilateral TMJ internal derangements. The chewing movements of an age- and gender-matched control group of 20 asymptomatic subjects (32·5±11·6 years, P>0·60) with verified normal TMJ function were also recorded. Means and standard deviations of the opening, closing, turning point, terminal chewing position, and velocity patterns were calculated. A two-tailed Student’s t-test with unequal variances was used to compare the parameters between the two groups (alpha = 0·05).Results:The dysfunctional group functioned significantly slower and with greater variability than the control group. The vertical dimension was consistently smaller in the dysfunctional group (P<0·00001). The terminal chewing position was significantly less precise in the dysfunctional group (vertical: P<0·002 and lateral: P<0·037). The maximum lateral width was significantly less (P<0·0071), and the peak and the average velocities were significantly lower (P<0·00001 for both) in the dysfunctional group.Conclusions:This group of dysfunctional subjects exhibited significantly slower, smaller, and more variable chewing patterns than the control group. The functional pattern of mastication appears to be significantly altered in the presence of an internal derangement of the TMJ.

Transcriptional regulation of proteoglycan 4 by 17β‐estradiol in immortalized baboon temporomandibular joint disc cells

Temporomandibular joint disorders (TMDs) affect a significant portion of the population of the USA, with the majority of those seeking treatment being women of childbearing age. Owing to this striking sexual dimorphism it has been postulated that sex hormones play a role in the maintenance of normal temporomandibular joint (TMJ) function. Proteoglycan 4 (PRG4) is a secreted lubricating molecule required for maintaining low frictional levels within articular joints; however, its role in the TMJ is not well characterized. In this study we describe the development of immortalized baboon cells isolated from specific regions of the TMJ disc and their use in the investigation of PRG4 expression and localization patterns in the TMJ. We identified conserved estrogen response elements within the 5' flanking region of the PRG4 gene of several species, and found that treatment of baboon TMJ disc cells with estrogen led to reduced PRG4 promoter activity and reduced expression of PRG4 mRNA in vitro. The observed negative regulation of PRG4 by estrogen could lead to increased friction and degradation of joint components over time. This study, for the first time, provides evidence of the regulatory potential of estrogen on PRG4 gene expression and suggests a novel etiology for the gender disparity observed among TMD patients.

Fiberscope Assisted Videolaryngoscope Intubation in the Surgical Treatment of TMJ Ankylosis.

Temporomandibular ankylosis is characterized by the formation of a bony mass which replaces normal temporomandibular joint (TMJ) articulation. Anaesthetic management in these patients requires expertise and dependable intubation technique that allows successful intubation due to anticipated difficulty in accessing the airway. A novel technique of endotracheal intubation is used for the successful airway management during the surgical treatment in patients with TMJ ankylosis with the assistance of fiberscope and GlideScope(®) videolaryngoscope. GlideScope(®) videolaryngoscope is a recently introduced system for tracheal intubation that has a dedicated video camera encased into a laryngoscope blade and provides better panoramic view than the conventional laryngoscopes. This technique avoids complications such as trauma to soft tissue structures surrounding the glottis during the passage of the tube over the fiberscope. It gives a clear view of the tube and its cuff position during intubation. It also abbreviates the time required for intubation which is a crucial determinant in this subset of patients owing to the difficult airway associated with paediatric age group.

Residents' journal review

Residents' journal review

Magnetic resonance imaging-verified temporomandibular joint disk displacement in relation to sagittal and vertical jaw deformities

This retrospective study was designed to analyze the relationships between temporomandibular joint (TMJ) disk displacement and skeletal deformities in orthodontic patients. Subjects consisted of 460 adult patients. Before treatment, lateral cephalograms and TMJ magnetic resonance imaging (MRI) were recorded. Subjects were divided into six groups based on TMJ MRI according to increasing severity of TMJ disk displacement, in the following order: bilateral normal TMJs, unilateral disk displacement with reduction (DDR) and contralateral normal, bilateral DDR, unilateral disk displacement without reduction (DDNR) and contralateral normal, unilateral DDR and contralateral DDNR, and bilateral DDNR. Subjects were subdivided sagittally into skeletal Class I, II, and III deformities based on the ANB (point A, nasion, point B) angle and subdivided vertically into hypodivergent, normodivergent, and hyperdivergent deformities based on the facial height ratio. Linear trends between severity of TMJ disk displacement and sagittal or vertical deformities were analyzed by Cochran–Mantel–Haenszel test. The severity of TMJ disk displacement increased as the sagittal skeletal classification changed from skeletal Class III to skeletal Class II and the vertical skeletal classification changed from hypodivergent to hyperdivergent. There were no significant differences in the linear trend of TMJ disk displacement severity between the sexes according to the skeletal deformities. This study suggests that subjects with skeletal Class II and/or hyperdivergent deformities have a high possibility of severe TMJ disk displacement, regardless of sex.

Conservative treatment modalities for patients with temporomandibular joint(TMJ) disorders

In the management of temporomandibular joint(TMJ) disorders, dental practioner should conduct the reversible, conservative, and inexpensive treatment modalities prior to the irreversible and invasive treatment. That is to say, behavioral, pharmacologic, and physical therapy should be conducted firstly, and then the occlusal appliance therapy could be considered. If patients do not react to these conservative treatments, we have to consider surgical treatments. If the accurate diagnosis is confirmed by intimate history taking, clinical and imaging examinations, we can rehabilitate the normal TMJ function and relieve the clinical symptoms with only conservative treatments in most TMJ disorder cases.

In vivo measurement of the 3D kinematics of the temporomandibular joint using miniaturized electromagnetic trackers: technical report

The aim of this study was to evaluate the use of miniaturized electromagnetic trackers (1 × 0.5 × 0.5 cm) fixed on teeth of the maxilla and mandible to analyse in vivo the 3D kinematics of the temporomandibular joint (TMJ). A third sensor was fixed to the forehead, and a fourth sensor was used as a stylus pointer to detect several anatomical landmarks in order to embed a local frame on the cranium. Temporomandibular opening/closing, chewing, laterotrusion and protrusion were examined. The prime objective within this study was to rigidly attach electromagnetic minisensors on teeth. The key for a successful affixation was the kevlar interface. The distances between the two mandibular affixed sensors and between the two maxillar affixed sensors were overall smaller than 0.033 cm for position and 0.2° for attitude throughout the temporomandibular motions. The relative motions between a forehead sensor and the maxilla affixed sensor are too big to suggest a forehead sensor as an alternative for a maxilla affixed sensor. The technique using miniaturized electromagnetic trackers furthers on the methods using electromagnetic trackers on external appliances. The method allows full range of motion of the TMJ and does not disturb normal TMJ function.

Application of magnetic resonance T2 mapping in the temporomandibular joints

The objective of this study was to apply magnetic resonance (MR) T2 mapping to the normal temporomandibular joint (TMJ) disk and to determine its T2 character. Fourteen volunteers with 28 healthy TMJs were selected for this study. MR T2 maps of all of the disks were acquired. The global disk area and 6 zonal regions of interest (ROIs) of superior, inner, and inferior layers and anterior, middle, and posterior bands were defined for each disk. T2 values of the global disk and each zonal ROI were calculated. Comparisons of the T2 values among the 3 layers and among the 3 bands were performed using the general linear model. The T2 value for the whole disk was 40.21 ± 2.95. The T2 values of the superior (39.42 ± 3.73) and inferior layers (40.11 ± 3.29) were significantly higher than the inner layer (37.28 ± 3.54) (P < .05). The T2 values of the anterior (36.96 ± 3.43) and posterior bands (36.01 ± 3.72) were significantly lower than the middle band (41.04 ± 5.51) (P < .05). Preliminary determinations of T2 values for the bands and layers of normal TMJ disks were calculated.

Contrast-enhanced MRI of normal temporomandibular joints in children--is there enhancement or not?

To determine the degree of contrast enhancement of normal TM joint (TMJ) in children and to provide reference data for patients with JIA. A total of 100 dynamic contrast-enhanced MRI of 46 children from 1.6 to 18 years (median 9.1 years), who underwent the examinations for reasons other than TMJ disease, were retrospectively analysed in accordance with our local ethics committee. Time-intensity curves of the mandibular condyle and the soft tissue of the joint were assessed in relation to pre-contrast images and to muscle tissue. After contrast injection the soft tissue of all joints showed a rapid initial increase of signal intensity (SI) followed by a slow increase, with the maximum after 6 min (end of the scan). Maximum SI in the joint tissue was on average 73% higher than pre-contrast, 53% higher than in the condyle and 20% higher than in an adjacent muscle. However, in 15% of measurements post-contrast SI of the muscle was higher than that of the joint tissue. The enhancement curve of the bone marrow in the condyle showed a peak by 2 min post-contrast. Contrast enhancement is a normal finding in the soft tissue and the condyle of the TMJ in children and adolescents. This should be taken into account when assessing the TMJ of children with JIA. As the relative enhancement of joint in comparison with muscle tissue proved to be variable, subtraction analysis of pre- and post-contrast T1 weighted images seems to provide a better basis for visual assessment.

ASSESSMENT OF FIVE OBLIQUE RADIOGRAPHIC PROJECTIONS OF THE CANINE TEMPOROMANDIBULAR JOINT

Investigation of temporomandibular joint (TMJ) disease requires a clear diagnostic image, which can be challenging to obtain using conventional radiography. The aim of this study was to compare five different oblique radiographic views with the head in lateral recumbency, assessing the clarity of visualization of the normal TMJ anatomy. The views under investigation were the laterorostral-laterocaudal oblique at a 10° and 20° rotation of the head ("nose-up" view), laterorostral-laterocaudal oblique with a rostrocaudal X-ray beam angulation of 10° and 20°, and a parallax view with the beam centered over C2 and collimated to include the TMJ region, using the divergence of the X-ray beam to project the TMJs separately on the radiograph. The views were performed on both TMJs of thirty canine cadavers and were graded independently by experienced and inexperienced observers. Grading was performed on the mandibular fossa, condylar process, joint space, retroarticular process, and the overall TMJ, and was based on a four-point scale. Mean grades for each component and for the overall joint were compared for each observer and each projection. Mean grades were significantly (P < 0.05) higher for the "Nose-up" projections than the angled beam or parallax projections, as was interobserver agreement, and both observers showed significantly higher (P < 0.05) mean grades for the 20(o) "Nose-up" angulation than the 10(o) "Nose-up" angulation. These results suggest that a latero 20(o) rostral-laterocaudal oblique gives the best representation of the anatomy of the TMJ of the dog of the projections assessed, and should be considered when investigating clinical cases of TMJ disease.

Computational synovial dynamics of a normal temporomandibular joint during jaw opening

Synovial fluid in the temporomandibular joint (TMJ) acts as a lubricant and shock absorber, facilitating smooth jaw movements by reducing friction and cushioning the articular cartilage and other tissues in the TMJ. This study investigated the flow pattern of synovial fluid in the articular cavity during jaw opening. The upper TMJ compartment in a healthy individual was studied by computed tomography arthrography, and the intra-articular pressures were measured during jaw opening. The compartment was reconstructed in three dimensions, and finite volume fluid dynamic modeling was used to analyze the pattern of fluid flow and pressure distribution during jaw movements. In a closed-jaw position, the upper joint compartment assumed a dumbbell shape. During the jaw opening process, the anterior portion of the upper compartment decreased gradually until it disappeared completely when the jaw was opened. As the jaw opened, the posterior space enlarged gradually. During jaw opening, the pressure in the anterior space of the upper compartment was higher than that in the posterior space. The model indicated that synovial fluid circulated anticlockwise, forming local vortices in both anterior and posterior spaces. During jaw opening processes, the three dimensional configuration of a normal upper TMJ compartment changed as the joint disc moved, with the synovial fluid circulating in an anticlockwise direction and local vortices forming.

Trps1 is necessary for normal temporomandibular joint development

Mutation of the human TRPS1 gene leads to trichorhinophalangeal syndrome (TRPS), which is characterized by an abnormal development of various organs including the craniofacial skeleton. Trps1 has recently been shown to be expressed in the jaw joints of zebrafish; however, whether Trps1 is expressed in the mammalian temporomandibular joint (TMJ), or whether it is necessary for TMJ development is unknown. We have analyzed (1) the expression pattern of Trps1 during TMJ development in mice and (2) TMJ development in Trps1 knockout animals. Trps1 is expressed in the maxillo-mandibular junction at embryonic day (E) 11.5. At E15.5, expression is restricted to the developing condylar cartilage and to the surrounding joint disc progenitor cells. In Trps1 knockout mice, the glenoid fossa of the temporal bone forms relatively normally but the condylar process is extremely small and the joint disc and cavities do not develop. The initiation of condyle formation is slightly delayed in the mutants at E14.5; however, at E18.5, the flattened chondrocyte layer is narrowed and most of the condylar chondrocytes exhibit precocious chondrocyte maturation. Expression of Runx2 and its target genes is expanded toward the condylar apex in the mutants. These observations underscore the indispensable role played by Trps1 in normal TMJ development in supporting the differentiation of disc and synoviocyte progenitor cells and in coordinating condylar chondrocyte differentiation.

Analysis of the cytokine profiles of the synovial fluid in a normal temporomandibular joint: Preliminary study

The purpose of this study was to compare the cytokine profiles of the synovial fluid from the temporomandibular joint (TMJ) spaces of normal individuals and temporomandibular disorder (TMD) patients. Thirty-four patients with planned orthognathic surgery did not present abnormalities of the TMJ on magnetic resonance images and radiographs and did not show the symptoms identified by the Research Diagnostic Criteria for TMD (RDC-TMD); as a result, they were assigned to the control group. Twenty-two patients who sought treatment for TMD during the same period were assigned to the TMD group. Synovial fluid was collected from superior TMJ spaces, and cytokine expression was analysed by an enzyme-linked immunosorbent assay (ELISA). Significant differences were tested using Fisher's exact test (p<0.05). Granulocyte Macrophage Colony stimulating Factor (GM-CSF), interferon (INF), interleukin (IL)-1β, IL-2, IL-6, IL-8, IL-10 and tumour necrosis factor (TNF)-α were detected in the TMD group, whereas no cytokines were detected in the control group. The most prevalent cytokines in the TMD group were IL-1β, IL-6 and GM-CSF. IL-4 and IL-5 were not detected in either the TMD group or in the control group. None of the cytokines that were detected in patients with TMD were found in the articular spaces of normal individuals.

Aquaporin 1 expression in human temporomandibular disc

Aquaporins (AQPs) are a family of hydrophobic membrane channel proteins. The expression of several AQP isoforms has been investigated in different human tissues, including the orofacial region. However, information on the role and localization of AQP1 in joints is limited, and no data are available on aquaporins in the normal temporomandibular joint (TMJ) disc. Sixteen human TMJ discs without degenerative changes were taken from fresh cadavers to investigate the presence and distribution of AQP1 by immunohistochemistry. The aim of the study was to gain additional insights into the biomolecular composition of aquaporins and their role in homeostasis of the TMJ. Porcine TMJ discs were also studied by Western blotting for comparison. Scattered AQP1 immunoexpression was detected in human disc cells, documenting its constitutive expression, but differences amongst the three disc regions were not significant. AQP1 expression was demonstrated in porcine TMJ disc by Western blotting. Our findings suggest that AQP1 is normally expressed in the TMJ disc and confirm a role for it in the maintenance of TMJ homeostasis. Further studies are needed to elucidate expression patterns of aquaporins in diseased TMJ discs.

Closed Reduction of Laterally Displaced Fracture/Dislocation of the Mandibular Condylar Process in a Child

This is a unique case of isolated lateral fracture/dislocation of the condylar process in a 3-year-old child injured on an escalator. Immediate closed reduction under general anesthesia successfully restored condylar height and premorbid dental occlusion. Maxillomandibular fixation was not used because mandibular mobilization was encouraged. Clinical follow-up confirmed maintenance of normal dental occlusion and temporomandibular joint function.

Cone-beam computed tomography to detect erosions of the temporomandibular joint: Effect of field of view and voxel size on diagnostic efficacy and effective dose

In this study, we examined the influence of field of view (FOV) and voxel size on the diagnostic efficacy of cone-beam computed tomography (CBCT) scans to detect erosions in the temporomandibular joint (TMJ). The sample consisted of 16 TMJs containing natural or artificially created erosions and 16 normal TMJs. CBCT scans were obtained with 3 imaging protocols differing in the FOV and the size of the reconstructed voxels. Two oral and maxillofacial radiologists scored the scans for the presence or absence of erosions. Diagnostic efficacies of the 3 imaging protocols were compared by using receiver operating curve analysis. For each TMJ imaging protocol, we used thermoluminescent dosimetry chips to measure the absorbed dose at specific organ and tissue sites. Effective doses for each examination were calculated. Areas under the receiver operating characteristic curves were 0.77 ± 0.05 for the 6-in FOV, 0.70 ± 0.08 for the 9-in FOV, and 0.66 ± 0.05 for the 12-in FOV. The diagnostic efficacy of the 6-in FOV, determined by the area under the curve, was significantly higher than that of the 12-in FOV (P≤0.05). Effective doses for bilateral TMJ evaluation were 558 μSv for the 6-in FOV, 548 μSv for the 9-in FOV, and 916 μSv for the 12-in FOV. The diagnostic efficacy of CBCT scans for the evaluation of erosive changes in the TMJ is highest for the 6-in FOV and lowest for the 12-in FOV.

Aquaporin 1 expression in human normal temporomandibular disc

The aquaporins (AQPs) are a family of hydrophobic membrane channel proteins that are expressed in many epithelial, endothelial and other tissues and that participate in many physiological and pathological processes. In particular aquaporin-1 (AQP1), a member of this family proteins, is expressed by the masseter and infrahyoid muscles, meckel’s cartilage and submandibular gland. Literature data on the role and the localization of AQP1 in articular joints are very poor, and none providing data on the normal temporomandibular joint (TMJ) disc. Accordantly, the present paper prompted this immunohistochemical and western blotting investigation, on the presence and distribution of AQP1 in human TMJ discs without any degenerative changes, in order to elucidate further aspects of the TMJ homeostasis system and disc tribology. Twelve TMJ discs, were obtained bilaterally from six cadavers and they were processed for immunohistochemical and Western Blot analysis. The results showed an AQP1 immunoexpression in few fibroblasts-like cells and fibrochondrocytes of normal human TMJ discs demonstrating a constitutive expression of this protein. No difference between the disc regions was seen in normal specimens. Western blot analysis of disc samples confirm the physiological AQP1 expression. In this view it appears reasonable a physiological expression of AQP1 by TMJ fibrocartilage cells and interpretable as a physiological mechanism of tissue homeostasis. Further future interesting studies could be conducted to elucidate the full AQPs profile in TMJ pathological disc investigating their change of the expression patterns during TMJ disc diseases.

Temporomandibular joint and 3.0 T pseudodynamic magnetic resonance imaging. Part 2: evaluation of articular disc obscurity

This study examined the relationship between temporomandibular joint (TMJ) dysfunctions and obscurity grades of interpreted anterior and posterior borders of the articular disc (Da and Dp, respectively) by 3.0 T pseudodynamic MRI. Da and Dp were classified into seven obscurity grades, and the Dp contour was classified into three types. The grades, types and TMJ function were compared by 3.0 T pseudodynamic MRI. Unobscured Da images at condylar positions posterior to the articular eminence were associated with normal TMJ function (P = 0.046 < 0.05). Unobscured Dp images at condylar positions anterior to the articular eminence were associated with normal TMJ function (P = 0.033 < 0.05). In addition, unobscured Dp images following flap insertion were associated with normal TMJ function (P = 0.043 < 0.05). There was no statistical relationship between Dp contour types and TMJ movement, but any change observed in the Dp contour during mouth opening was associated with abnormal TMJ function (P = 0.040 < 0.05). Grading of Da and Dp obscurity based on how well the areas were defined in the images, identifying the condylar positions in relation to the glenoid fossa and articular eminences, and observing the changes in Dp contour types were useful for diagnosing TMJ abnormalities.

Condylar volume and surface in Caucasian young adult subjects

BackgroundThere have been no quantitative standards for volumetric and surface measurements of the mandibular condyle in Caucasian population. However, the recently developed cone-beam computed tomography (CBCT) system allows measurement of these parameters with high accuracy.MethodsCBCT was used to measure the condylar volume, surface and the volume to surface ratio, called the Morphometric Index (MI), of 300 temporo-mandibular joints (TMJ) in 150 Caucasian young adult subjects, with varied malocclusions, without pain or dysfunction of TMJs.ResultsThe condylar volume was 691.26 ± 54.52 mm3 in males and 669.65 ± 58.80 mm3 in, and was significantly higher (p< 0.001) in the males. The same was observed for the condylar surface, although without statistical significance (406.02 ± 55.22 mm2 in males and 394.77 ± 60.73 mm2 in females).Furthermore, the condylar volume (693.61 ± 62.82 mm3 ) in the right TMJ was significantly higher than in the left (666.99 ± 48.67 mm3, p < 0.001) as was the condylar surface (411.24 ± 57.99 mm2 in the right TMJ and 389.41 ± 56.63 mm2 in the left TMJ; t = 3.29; p < 0.01). The MI is 1.72 ± 0.17 for the whole sample, with no significant difference between males and females or the right and left sides.ConclusionThese data from temporomandibular joints of patients without pain or clinical dysfunction might serve as examples of normal TMJ's in the general population not seeking orthodontic care.