The thickness of the roof of the glenoid fossa in the temporomandibular joint: relationship to the MRI findings

OBJECTIVES: The purpose of this study was to clarify the relationship between the thickness of the roof of the glenoid fossa (RGF) and magnetic resonance imaging (MRI) findings of temporomandibular joint (TMJ) disorders (TMDs). METHODS: Eighty-seven patients with symptoms and indications of TMD in one or both TMJs were referred for MRI. Cone-beam CT (3DX) was used to measure the thickness of the RGF at its thinnest point. Linear measurements were made three times on the monitor by three separate investigators and the mean values obtained were used for the statistical analyses. RESULTS: The joints were categorised as normal (70 joints), anterior disc displacement with reduction (ADWR; 53 joints) or anterior disc displacement without reduction (ADWOR; 51 joints). The joint disorders were also categorised into the following subgroups: with osteoarthritis (OA) (21 joints), without OA (153 joints), with disc deformation (33 joints), without disc deformation (141 joints), with joint effusion (JE) (61 joints) and without JE (113 joints). The average minimum thickness of the RGF was 0.85 mm for normal joints, 0.90 mm with ADWR, 0.93 mm with ADWOR, 0.99 mm with OA, 0.87 mm without OA, 0.87 mm with disc deformation and 0.89 mm without disc deformation. There was no significant difference between these figures. There was a significant difference in the thickness of the RGF with (0.97 mm) and without (0.84 mm) JE. CONCLUSIONS: These results suggest that RGF thickness is influenced by JE, but is unaffected by disc position and configuration.     

The contribution of frontal tomography to the diagnosis of temporomandibular joint osteoarthritis.

The contribution of frontal tomography to the diagnosis of temporomandibular joint (TMJ) osteoarthritis has been investigated. Ninety-one patients with clinically defined TMJ disorders were examined by simultaneous lateral and frontal TMJ tomograms taken in the intercuspal position. Abnormal findings were observed on frontal tomograms in 31 joints and suspicious findings in 22 joints. On the other hand, there were 41 joints with abnormal findings and 22 joints with suspicious findings on the lateral tomograms. Suspicious or abnormal findings were found on frontal tomograms alone in 14 joints (7.7%) of 14 patients (15.4%). It is concluded that simultaneous lateral and frontal tomography produces a more accurate radiographic diagnosis of TMJ osteoarthritis.     

Air in the temporomandibular joint fossa: CT sign of temporal bone fracture

Temporal bone fractures can be difficult to detect clinically and radiographically. Air is sometimes present in the glenoid fossa of the temporomandibular joint (TMJ) at computed tomography (CT) of acute basilar skull fractures. This study evaluated TMJ fossa air as a sign of temporal bone fracture. Initial CT scans of the head in 114 patients with a diagnosis of basilar skull fracture at discharge were retrospectively reviewed. TMJ fossa air was present in 23 of 114 patients (20.2%) and was bilateral in three patients. Only temporal bone fractures were significantly (P less than .001) associated with TMJ fossa air. Temporal bone fractures were observed at CT in 23 of 26 cases of TMJ fossa air, but in three of 26 cases, TMJ fossa air was the only CT sign of clinically apparent temporal bone fractures. TMJ fossa air is associated with acute temporal bone fracture and may be the only CT sign of an otherwise inconspicuous temporal bone fracture.     

Clinical application of SPHARM-PDM to quantify temporomandibular joint osteoarthritis

The severe bone destruction and resorption that can occur in osteoarthritis of the temporomandibular joint (TMJ) is associated with significant pain and limited joint mobility. However, there is no validated method for the quantification of discrete changes in joint morphology in early diagnosis or assessment of disease progression or treatment effects. To achieve this, the objective of this cross-sectional study was to use simulated bone resorption on cone-beam CT (CBCT) to study condylar morphological variation in subjects with temporomandibular joint (TMJ) osteoarthritis (OA). The first part of this study assessed the hypothesis that the agreement between the simulated defects and the shape analysis measurements made of these defects would be within 0.5 mm (the image's spatial resolution). One hundred seventy-nine discrete bony defects measuring 3 mm and 6 mm were simulated on the surfaces of 3D models derived from CBCT images of asymptomatic patients using ITK-Snap software. SPHARM shape correspondence was used to localize and quantify morphological differences of each resorption model with the original asymptomatic control. The size of each simulated defect was analyzed and the values obtained compared to the true defect size. The statistical analysis revealed very high probabilities that mean shape correspondence measured defects within 0.5 mm of the true defect size. 95% confidence intervals (CI) were (2.67, 2.92) and (5.99, 6.36) and 95% prediction intervals (PI) were (2.22, 3.37) and (5.54, 6.82), respectively for 3 mm and 6 mm simulated defects. The second part of this study applied shape correspondence methods to a longitudinal sample of TMJ OA patients. The mapped longitudinal stages of TMJ OA progression identified morphological variants or subtypes, which may explain the heterogeneity of the clinical presentation. This study validated shape correspondence as a method to precisely and predictably quantify 3D condylar resorption.     

CT and MR of the temporomandibular joint: comparison with autopsy specimens

CT and MR imaging have been advocated for use in the diagnosis of disorders of the temporomandibular joint. A systematic comparison of these imaging techniques has not been made. We performed direct sagittal CT and sagittal MR on 15 fresh temporomandibular joint autopsy specimens and compared our diagnoses with cryosectional findings in a blinded fashion. We found no statistically significant differences between these procedures in detecting bony abnormalities or disk position. However, a side-by-side comparison between the CT and MR images demonstrated that MR depicted the soft-tissue anatomy of the joint with greater detail than did CT. Thus, MR clearly displayed the disk when it was positioned either superiorly or anteriorly, whereas CT only showed the disk adequately when it was positioned anteriorly. MR further showed the configuration of the disk and the borderlines between the disk and its attachments; these relationships could not be assessed from CT images. This experimental study indicates that MR is superior to CT for depiction of soft-tissue changes, whereas CT is superior in showing osseous abnormalities. Clinical confirmation of these results is necessary before one method can be definitively recommended over the other for clinical studies.     

Effectiveness of bone scans in the diagnosis of osteoarthritis of the temporomandibular joint

Objective

The objective of this study was to evaluate the usefulness of bone scan procedures for the diagnosis of temporomandibular joint (TMJ) osteoarthritis.

Methods

From February 2009 to June 2009, 22 patients (4 males and 18 females) from Seoul National University Bundang Hospital, Republic of Korea, were diagnosed with TMJ disorder. They were examined by clinical examination, plain radiograph and bone scan and were categorized into three groups: normal, internal derangement and osteoarthritis. TMJ uptake ratios and asymmetrical indices were calculated.

Results

There were no significant differences in uptake ratios associated with pain and bone change. However, significant results were obtained when comparing uptake ratios between the osteoarthritis and non-osteoarthritis groups.

Conclusion

It was concluded from this study that bone scans may help to diagnose osteoarthritis when increased uptake ratios are observed.     

Evaluation of the usefulness of the limited cone-beam CT (3DX) in the assessment of the thickness of the roof of the glenoid fossa of the temporomandibular joint

OBJECTIVES: The purpose of this study was to evaluate the usefulness of the limited cone-beam X-ray CT (3DX) (Morita Co., Japan) in measuring the thickness of the roof of the glenoid fossa (RGF) of the temporomandibular joint (TMJ). MATERIALS AND METHODS: Twenty-one TMJs removed at autopsy from 21 cadavers were investigated macroscopically using dissection and 3DX imaging. A Digimatic Outside Micrometer and a 3DX-image tool were used to measure the minimum thickness of the RGF. Multiple measurements were made to identify the thinnest area. Once the thinnest areas had been identified, three linear measurements were made and the average value was used for statistical analysis. RESULTS: The average macroscopic examination measurement was 1.37 mm (range 0.55-3.6 mm) and the average 3DX image measurement was 1.22 mm (range: 0.51-3.0 mm). There was no significant difference between these two groups using the Mann-Whitney U-test (P < 0.05). The Spearman's correlation coefficient by rank between these two groups was r = 0.93(P < 0.001). CONCLUSION: These results suggest that bone thickness measurements of the RGF by 3DX imaging was effective.     

Inflammatory orbital pseudotumor with infratemporal fossa extension mimicking temporomandibular joint dysfunction

Inflammatory orbital pseudotumor is a benign space-occupying lesion of unknown origin that involves all or part of the fatty tissue within the orbit. Occasionally the disease may extend into the middle cranial, the pterygopalatine, and the infratemporal fossa through the various foramina of the orbit, although extension into the infratemporal fossa is very rare. We present a case which extends into the infratemporal fossa through the inferior orbital fissure, resulting in presenting symptoms mimicking temporomandibular joint dysfunction.     

Comparison of computed with conventional tomography in the evaluation of temporomandibular joint disease: a study of autopsy specimens

Autopsy specimens were examined both radiographically and macroscopically to compare direct computed tomography (CT) with conventional tomography (CVT) for their diagnostic yield of the structural bone changes in the temporomandibular joint (TMJ). Fifteen specimens were examined with corrected sagittal and 12 with corrected frontal tomography. Five joints showed bone exposure and/or disc perforation macroscopically and all of them were correctly diagnosed by both CT and CVT (sensitivity 1.0). However, false-positive diagnoses were also made, resulting in values for specificity which were somewhat lower for CT than for CVT. Frontal images did not reveal any additional 'true' findings compared with sagittal CT or CVT. For single areas of the joints the average sensitivity was low, 0.28 for CT and 0.47 for CVT, but the specificity for the joint as a whole was high with both methods (0.91 and 0.94 respectively). We conclude that CVT is superior to CT in the diagnosis of single structural bone changes but comparable for comprehensive diagnosis of TMJ disease.     

Relationship between patient characteristics, mandibular head morphology and thickness of the roof of the glenoid fossa in symptomatic temporomandibular joints

OBJECTIVE: The purpose of this clinical study was to investigate the minimum thickness of the roof of the glenoid fossa (RGF) of grossly normal temporomandibular joints (TMJ) and to correlate this with patient gender, age and the morphological classification of the mandibular head. METHODS: The study was performed on 191 TMJs from 109 patients (25 male and 84 female, age range 3-79 years, mean age 28.1 years) who visited Nihon University Dental Hospital, Japan with suspected TMJ disorders. The patients underwent cone beam computed tomography (3DX CT) to enable observation of the morphological features of the mandibular head. The minimum thickness of the RGF was measured using frontal section images acquired by CT. The morphology of the mandibular heads was classified according to the method of Yale and colleagues. Mean linear measurements were used for statistical analyses of patient gender, age and mandibular head morphology. RESULTS: The average minimum thickness of the RGF was 0.79 mm. No significant difference in thickness was found between male and female patients. In addition, no differences were recorded as a result of variation in age or mandibular head morphology. CONCLUSIONS: These results indicate that RGF thickness is not significantly correlated with gender, age, or mandibular head morphology, at least in this cohort of patients.     

Imaging of the temporomandibular joint: An update

Imaging of the temporomandibular joint (TMJ) is continuously evolving with advancement of imaging technologies. Many different imaging modalities are currently used to evaluate the TMJ. Magnetic resonance imaging is commonly used for evaluation of the TMJ due to its superior contrast resolution and its ability to acquire dynamic imaging for demonstration of the functionality of the joint. Computed tomography and ultrasound imaging have specific indication in imaging of the TMJ. This article focuses on state of the art imaging of the temporomandibular joint. Relevant normal anatomy and biomechanics of movement of the TMJ are discussed for better understanding of many TMJ pathologies. Imaging of internal derangements is discussed in detail. Different arthropathies and common tumors are also discussed in this article.     

Routine tomography of the temporomandibular joint.

Routine lateral tomography of the temporomandibular joint has resulted in a three-fold increase in the detection of positive findings. The technique is easily accomplished, eliminates the problem of superimposition of unwanted structures, permits a true lateral view of the condyle and condylar fossa, and allows small articular surface abnormalities to be identified. Although the entrance skin dose to the patient's face in the beam is about two times greater per exposure than that for our previous conventional open and closed lateral views, we believe that the increased dose is reasonable and the resulting improved diagnostic accuracy outweighs this disadvantage.     

Theoretical presuppositions in the precise tomographic study of the temporomandibular joint

In order to eliminate typical projective distortions of lateral or standard oblique tomography of the temporo-mandibular joint, authors suggest a preliminary evaluation of the long condylar axis inclination by means of axial radiograph. This method allows to personalize, for each side, the slope of X-ray beam to perform an effectual oblique tomography.     

Diaphyseal aclasis affecting the temporomandibular joint.

Diaphyseal aclasis is a rare disorder of bone development in which multiple, cartilagenous exostoses develop and enlarge mainly on the ends of long bones. It has also been described in the vertebral column where it may give rise to spinal cord compression but has not previously been reported as occurring in the jaws. A case is reported in which a patient known to suffer from diaphyseal aclasis at many other anatomical sites displays temporomandibular joint changes which are highly suggestive of the disease now manifesting in the jaws. The presentation, investigations and treatment are described and the literature concerning previous cases of diaphyseal aclasis is reviewed.     

Thickness of the roof of the glenoid fossa and condylar bone change: a CT study

OBJECTIVES: The aim of this study is to investigate the relationship between the thickness of the roof of the glenoid fossa in the temporomandibular joint (TMJ) and the existence and types of condylar bone change. MATERIALS AND METHODS: Helical CT was used to measure the thickness of the roof of the glenoid fossa at its thinnest part in 37 orthodontic patients with temporomandibular disorders. Condylar bone changes were classified into four types: no bone change (24 joints); flattening (19 joints); osteophyte formation (13 joints); and erosion (18 joints). RESULTS: The roof of the glenoid fossa was significantly thicker in joints with bone change than in joints with no bone change (Mann-Whitney U-test, P<0.05). There was also a significant difference in relation to the type of condylar bone change: the thickness of the roof of the glenoid fossa in the erosion group was significantly greater than in the no bone change (P<0.01), flattening (P<0.05) and osteophyte formation (P<0.05) groups (Kruskal-Wallis and Games-Howell tests). CONCLUSION: Compensative bone formation in the roof of the glenoid fossa might help to withstand the increased stress in the TMJ accompanying condylar bone change, especially erosion.