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

Assessment of thickness of roof of the glenoid fossa in dentate, edentulous, and partially edentulous subjects using cone beam computed tomography (CBCT) - a retrospective study

OBJECTIVES

Studies have inferred a direct association between Temporomandibular joint disorders (TMD) and the integrity of the structures associated with it such as the Glenoid fossa thereby necessitating the requirement to measure the thickness of this oft ignored entity. This study was carried out to assess the thickness of the glenoid fossa roof in dentulous, edentulous, and partially edentulous subjects using archival Cone beam computed tomography (CBCT) images.

METHOD

Analysis of CBCT data of 120 joints from 60 adult subjects without signs and symptoms of TMD was carried out. The scans were grouped based on the dental status as dentulous, edentulous, and partially edentulous and additionally into two sets as those below and above 40 years of age. The distance between the superior and inferior cortices of the glenoid fossa was measured indicating the thickness of the roof of the glenoid fossa in the coronal and sagittal planes, by three independent observers. Analysis of Variance (ANOVA) and Tukey's post hoc test were used to compare the association between the mean thickness of the glenoid fossa and the dentition status. A p ≤ 0.05 was considered to be significant.

RESULTS

There was no significant association between the mean thickness of the glenoid fossa and the dentition of the study participants of all three groups, when assessed by the three observers, except the mean thickness on the right side in the sagittal section as measured by one observer. A thicker fossa was observed in edentulous subjects when compared to dentulous participants, and the difference was statistically significant (p = 0.035).

CONCLUSION

The thickness of the roof of the glenoid fossa demonstrated no association with the dental status of the study participants and no age or sex related differences were noted.

Interaction effect of tegmen tympani and superior semicircular canal statuses on the thickness of the roof of the glenoid fossa: a cross-sectional descriptive study

PURPOSE

Homogeneous development of temporal bone structures is explained by their ontogenic origin; tegmen tympani (TT) and superior semicircular canal (SSC) are related with the glenoid fossa at the temporomandibular joint (TMJ). Therefore, our objective was to determine a possible relationship between TT status (dehiscence or integrity) and the roof of the glenoid fossa (RGF) thickness; SSC status has also been considered.

METHODS

This cross-sectional descriptive study was conducted in two tertiary hospitals on 95 patients (109 ears) presenting hypoacusia, facial palsy, vertigo, tinnitus, and other single or combined symptoms, and submitted to a thin-section multidetector-row computed axial tomography (CT) scan.

RESULTS

A significant interaction effect of TT × SSC statuses on RGF thickness was found (p = 0.049). A significant difference in RGF thickness was found only for SSC integrity status between TT integrity and TT dehiscence (p = 0.004). The TT dehiscence increased the risk for RGF dehiscence 12.047 times (p = 0.002).

CONCLUSIONS

There is an interaction effect of the statuses of both TT and SSC on the thickness of the RGF, instead of an independent effect of the TT status. When RGF dehiscence is found, TT and SSC statuses should be assessed, to discard associated dehiscences.

Comparison between Glenoid Fossa Roof Thickness in TMD and non-TMD Patients, a CBCT Study

Statement of the Problem

Various pathologic conditions can affect the thickness of the roof of glenoid fossa (RGF). The relationship between the RGF thickness and temporomandibular joint disorder (TMD) is not explicitly investigated. Considering the changes in RGF thickness, as a radiographic sign for TMD diagnosis, the phenomenon may necessitate specific treatment and may influence the treatment course and results.

Purpose

This research was designed to examine the relationship between TMD and RGF thickness changes compared to non-TMD group.

Materials and Method

In this cross sectional analytic research CBCT images of 70 TMD patients (140 joints) and 70 non-TMD individuals (140 joints) as control group were evaluated for thickness of RGF and presence of discontinuity in RGF. The distance between superior and inferior cortex of glenoid fossa was measured as RGF thickness. Inability to follow the course of cortex in any given image was considered as discontinuity. T-test, Chi-square and odds ratio (OR) were used for statistical analysis. In this study, p< 0.05 was considered meaningful.

Results

The mean thickness of RGF in our non-TMD samples was 1.12 mm. RGF thickness was significantly increased in TMD patients compared non-TMD group (p= 0.00). This value was also greater in males. On the other hand, TMD patient showed a higher incidence of discontinuity in RGF, in comparison with non-TMD patients (p= 0.006).

Conclusion

The increased thickness of RGF can be considered as a sign of TMD, which may help in diagnosis of TMD. It seems that there is a direct relationship between TMD and discontinuity of RGF.

Correlation between temporomandibular joint morphometric measurements and gender, disk position, and condylar position

OBJECTIVE

The aim of this study was to correlate the morphometric measurements of the temporomandibular joint, including condylar size, joint space, and articular eminence size, with gender, disk position, and condylar position by using magnetic resonance imaging.

STUDY DESIGN

Overall, 93 patients were evaluated (31.2% males and 68.8% females; age 18-81 years; mean age 41 years). Condylar size (D1), joint space (D2), and eminence size (D3) were measured. Correlations with gender, disk position, and condylar position were calculated.

RESULTS

A statistically significant correlation was found between D2 and gender, with the joint space being significantly larger in the male group (P = .05). There were correlations between D2 and the position of the disk and the position of the condyle (P ≤ .05).

CONCLUSIONS

The results indicate a correlation between male gender and larger joint space. In addition, we found that the joint space size influences the articular disk and condyle position, which can cause disk displacement.

Radiologic correlation between the thickness of the roof of the glenoid fossa and that of the bony covering of the superior semicircular canal

OBJECTIVES

Dehiscence of the superior semicircular canal (SSC) has been associated with alteration of the temporomandibular joint, although data explaining this association are lacking. The present study examined the correlations between the presence of dehiscences and thickness of the bone covering the SSC and the roof of the glenoid fossa (RGF).

STUDY DESIGN

Computed tomography was used in a cross-sectional analysis of the presence of dehiscences and thickness of the bone overlying the SCC and RGF in 156 temporal bones of 78 patients. The correlations of the presence of dehiscences in the SSC and ipsilateral RGF and the thickness of bone covering the SSC and RGF were analyzed by using the χ² or Fisher's exact test. The relationship between the thickness of the bone overlying the SCC and RGF was analyzed by using the Spearman correlation coefficient and the Kruskal-Wallis test. The relationship between the thickness of the RGF and the covering of the SCC and patient age and gender was analyzed with the general linear model.

RESULTS

Significant correlations were found between the presence of dehiscences and thickness of the bone overlying the SSC and RGF (P < .001).

CONCLUSIONS

There is a morphologic relationship between the structure of the SSC and RGF.

Usefulness of MRI-CBCT image registration in the evaluation of temporomandibular joint internal derangement by novice examiners

OBJECTIVE

To assess whether novice examiners can more reliably determine temporomandibular joint (TMJ) disk derangements with the use of fused images of magnetic resonance imaging and cone beam computed tomography (MRI-CBCT) compared with MRI images alone.

STUDY DESIGN

Thirty dental students with minimal exposure to TMJ imaging received a 30-minute calibration session in which TMJ diagnostic imaging and the normal anatomy of the TMJ internal derangement were explained. The students evaluated the disk positions of 16 TMJs in two sets of images (MRI images alone and MRI-CBCT images) randomly and independently. The disk positions evaluated by two experienced radiologists were used for comparison.

RESULTS

The internal consistency among all students improved from an unacceptable consistency (α = 0.40) with MRI images alone to a good consistency (α = 0.84) with MRI-CBCT images. The agreement in evaluation between the students and the radiologists improved from a poor agreement with MRI images alone (k mean = 0.07 ± 0.12) to a moderate agreement with MRI-CBCT images (k mean = 0.55 ± 0.25). This improvement in the agreement was significant (P < .001).

CONCLUSIONS

The use of fused MRI and CBCT images to visualize the TMJ in a single display significantly improved the examiners' reliability and accuracy of assessment of disk positions. The improvement of novice readers in assessing the disk positions highlights the potential use of MRI-CBCT image fusion as an educational tool.

MRI analysis of the relationship between bone changes in the temporomandibular joint and articular disc position in symptomatic patients

OBJECTIVES

The aim of this study was to investigate bone changes in the condyle, articular eminence and glenoid fossa in relation to the position of the articular disc.

METHODS

148 temporomandibular joints (TMJs) of 74 symptomatic patients who underwent MRI were evaluated. The position of the disc was classified as either normal (N), disc displacement with reduction (DDwR), disc displacement without reduction (DDwoR) and posterior displacement (PD). Bone changes were investigated in the condyle and temporal components of the TMJ and classified as osteophytosis, sclerosis or erosion.

RESULTS

There were no bone changes in the glenoid fossa of the temporal bone. Of the total number of TMJs studied, 94 (63.5%) were N, 34 (23%) presented DDwoR, 19 (12.8%) presented DDwR and 1 (0.7%) presented PD. The bone changes in the condyle and posterior aspect of the articular eminence were associated with the position of the disc. The bone changes in the anterior aspect of the articular eminence were not associated with the position of the disc.

CONCLUSION

In cases of DDwoR, bone changes in the condyles were more common. The combination of erosion and osteophytosis in the condyle and the bone changes of the posterior aspect of the articular eminence were associated with disc position.

Evaluation of the usefulness of magnetic resonance imaging in the assessment of the thickness of the roof of the glenoid fossa of the temporomandibular joint

OBJECTIVE

The aim of this study was to evaluate the usefulness of magnetic resonance imaging (MRI) in measuring thickness of the roof of the glenoid fossa (RGF) of the temporomandibular joint (TMJ).

STUDY DESIGN

Minimum RGF thickness in 95 TMJs of 59 patients with temporomandibular disorders were measured and compared on both sagittal-section MRI and cone-beam computed tomography (CBCT). RGF thickness on MRI was also compared with MRI, CBCT, and arthrographic findings.

RESULTS

Minimum RGF thickness was greater on MRI (1.46 mm) than on CBCT (0.90 mm). Spearman's correlation coefficient by rank for these 2 types of measurements was 0.63. RGF thickness on MRI differed significantly between those with and without degenerative joint changes (1.69 vs 1.32 mm; P < .01) and between those with and without disk displacement (1.58 vs 1.35 mm; P = .04), but showed no associations with disk deformity, joint effusion, or disk perforation.

CONCLUSIONS

MRI is useful in measuring RGF thickness from diagnostic as well as radiation protection standpoints.

The influence of secondary reconstruction slice thickness on NewTom 3G cone beam computed tomography-based radiological interpretation of sheep mandibular condyle fractures

OBJECTIVE

The objective of this study was to examine the diagnostic accuracy of the different secondary reconstruction slice thicknesses of cone beam computed tomography (CBCT) on artificially created mandibular condyle fractures.

METHODS

A total of 63 sheep heads with or without condylar fractures were scanned with a NewTom 3G CBCT scanner. Multiplanar reformatted (MPR) views in 0.2-mm, 1-mm, 2-mm, and 3-mm secondary reconstruction slice thicknesses were evaluated by 7 observers. Inter- and intraobserver agreements were calculated with weighted kappa statistics. The receiver operating characteristic (ROC) curve analysis was used to statistically compare the area under the curve (AUC) of each slice thickness.

RESULTS

The kappa coefficients varied from fair and to excellent. The AUCs of 0.2-mm and 1-mm slice thicknesses were found to be significantly higher than those of 2 mm and 3 mm for some type of fractures.

CONCLUSION

CBCT was found to be accurate in detecting all variants of fractures at 0.2 mm and 1 mm. However, 2-mm and 3-mm slices were not suitable to detect fissure, complete, and comminuted types of mandibular condyle fractures.

In vivo morphometric analysis of inflammatory condylar changes in rat temporomandibular joint

OBJECTIVE

Injection of complete Freund's adjuvant (CFA) into the temporomandibular joint (TMJ) causes acute swelling around the joint and subsequent morphological alterations in the condyle. We aimed to evaluate changes in the three-dimensional architecture of the condyle induced with CFA.

MATERIALS AND METHODS

The CFA was injected into the unilateral TMJ of rats and morphological changes in the condyle were assessed repeatedly for 14 days by in vivo micro-CT.

RESULTS

Osseous abnormalities of condyle were first observed at 3-5 days after CFA injection on the tomographic images, and the condylar deformation became more obvious thereafter. Among 12 condyles examined at 14 days postinjection, osteophytosis was observed in all of the specimens and bone erosion coexisted in five condyles. None of the saline-treated condyles showed architectural changes. Significant changes were detected in the mesiolateral and rostrocaudal widths of the CFA-treated condyles at 10-14 days postinjection (P < 0.01). The extent of both condylar bone formation and resorption was greater in the CFA-injected TMJs than in saline-injected TMJs (P < 0.05).

CONCLUSION

These results indicate that CFA causes dynamic morphological changes in the condyle and that our experimental approach will provide new insights into the subacute inflammatory processes in the TMJ.

Diagnostic accuracy of microcomputed tomography for osseous abnormalities in the rat temporomandibular joint condyle

OBJECTIVES

Our aim was to investigate the diagnostic accuracy of in vivo micro-CT for osseous abnormalities of the rat temporomandibular joint (TMJ) condyle, using macroscopic observations as the "gold standard".

METHODS

A 30 TMJ arthritis model was prepared by injecting inflammatory complete Freund's adjuvant (CFA) into one side of the TMJ cavities of rats. The TMJ condyles were then imaged using micro-CT. The samples were macroscopically evaluated for osseous abnormalities, including erosions, osteophytes, flattening and concavity. The micro-CT images were independently assessed for abnormalities using the same criteria. Images in three planes were produced using the micro-XYZ technique with the micro-CT equipment.

RESULTS

According to the macroscopic observations, 26 of the 60 rat condyles showed osseous abnormalities. The micro-XYZ images detected abnormalities in 25 of the condyles. The condyle diagnostic accuracy of micro-CT was 0.98, the sensitivity was 0.96 and the specificity was 1.0.

CONCLUSIONS

Good diagnostic results were obtained using micro-CT. It is therefore an effective technique for the evaluation of osseous abnormalities in the rat TMJ condyle.