|Year : 2021 | Volume
| Issue : 1 | Page : 41-47
Evaluation of morphometric and volumetric measurements of temporomandibular joint structures on patients with disc displacement
Melike Basaran1, Esin Bozdemir2, Sehnaz Evrimler3
1 Department of Dentomaxillofacial Radiology, Faculty of Dentistry, Kutahya Health Sciences University, Kutahya, Turkey
2 Department of Dentomaxillofacial Radiology, Faculty of Dentistry, Suleyman Demirel University, Isparta, Turkey
3 Department of Radiology, Faculty of Medicine, Suleyman Demirel University, Isparta, Turkey
|Date of Submission||29-Apr-2020|
|Date of Acceptance||15-Feb-2021|
|Date of Web Publication||07-Apr-2021|
Dr. Melike Basaran
Department of Dentomaxillofacial Radiology, Faculty of Dentistry, Kutahya Health Sciences University, Kutahya
Source of Support: None, Conflict of Interest: None
Introduction: To evaluate the morphometric and volumetric measurements of the temporomandibular joint (TMJ) structures, of healthy, anterior disc displacement with reduction (ADDWR) and anterior disc displacement without reduction (ADDWoR) joints using magnetic resonance imaging (MRI). Material and Methods: Fifty-two TMJs of 38 patients with TMJ disorders and 26 TMJs of 13 healthy patients were evaluated on MRI images. The disc length and volume, the condylar height, width and volume, and the height and inclination of the articular eminence were measured on MRI. A one-way analysis of variance was used to establish the differences between the values with regard to the ADDWR, ADDWoR, and control groups. The differences in the disc volumes of each group with respect to open and closed mouth position statuses were evaluated using the Bonferroni test. Results: The articular disc mean volume was larger in the control group than the other two groups for both the closed and open mouth positions (P < 0.05). There were statistically significant differences between the control group and the other two groups in terms of the condylar width and disc length (P = 0.00 and P = 0.001, respectively). The mean articular eminence inclination was the lowest in the ADDWoR group and the highest in the control group (P = 0.02). Discussion and Conclusion: Measurements of the disc volume, disc length, condylar width, and articular eminence inclination are associated with disc displacement (DD). Degenerative changes that may cause morphometric and volumetric changes in TMJ structures may be a marker of TMJ DD.
Keywords: Magnetic resonance imaging, mandibular condyle, temporomandibular joint disc, temporomandibular joint disorders
|How to cite this article:|
Basaran M, Bozdemir E, Evrimler S. Evaluation of morphometric and volumetric measurements of temporomandibular joint structures on patients with disc displacement. J Anat Soc India 2021;70:41-7
|How to cite this URL:|
Basaran M, Bozdemir E, Evrimler S. Evaluation of morphometric and volumetric measurements of temporomandibular joint structures on patients with disc displacement. J Anat Soc India [serial online] 2021 [cited 2023 Feb 4];70:41-7. Available from: https://www.jasi.org.in/text.asp?2021/70/1/41/313165
| Introduction|| |
The temporomandibular joint (TMJ) is an articulation between the mandibular condyle and the mandibular fossa and articular eminence. The articular disc is positioned between the condyle and the temporal bone components, and it has a biconcave shape with a thick anterior band, thicker posterior band and thin middle part. In normal disc-condyle relationship, the posterior band is located above the condyle near the 12 o'clock position. In the open mouth position, the thin intermediate zone lies between the condylar head and the articular eminence. TMJ disc displacement (DD) is one of the most commonly seen pathologies in the internal derangement (ID) of the TMJ, and it is defined as an abnormally positioned or displaced disc. The disc can become displaced in any direction but anterior DD is most common type of DD., Magnetic resonance imaging (MRI), which is a radiation-free, noninvasive imaging modality with high tissue contrast, is currently the best imaging method for evaluating the disc and diagnosing DD.,, Many authors have assessed the morphometric characteristics of the TMJ, and they have suggested that DD could lead to changes in the morphology and morphometric characteristics of TMJ.,,,, Although there have been studies evaluating the morphometric and volumetric measurements of the TMJ in patients with DD,,,, there have been few studies that have determined the relationship between the disc volume and DD in the literature., Therefore, the purpose of this study was to evaluate the morphometric and volumetric features of the TMJ structures of healthy, anterior DD with reduction (ADDWR), and anterior DD without reduction (ADDWoR) joints using MRI.
| Material and Methods|| |
This prospective study was approved by the 98,227 project number by the clinical research ethics committee of the university hospital, and the participants signed approved consent forms. Fifty-two TMJs of 38 patients (6 males and 32 females) with Temporomandibular disorders (TMD) and 26 TMJs of 13 healthy patients (7 males and 6 females) were evaluated in the present study. All patients included in this study were clinically examined according to the Research diagnostic criteria for TMD axis I protocol. As a result of clinical examination, patients between 18 and 40 years' old who presented at least two positive clinical TMD symptoms underwent MRI examinations and then patients who detected anterior DD on MRI images included in the TMD group. Patients who had no clinical TMD symptom and normal disc-condyle relationship on MRI images were included in the control group. The exclusion criteria were as follows: Systemic or inflammatory joint diseases, congenital deformities or syndromes, trauma, maxillofacial bone fractures, or surgeries in the TMJ area.
Magnetic resonance imaging examination
The MRI examinations were performed using a 1.5 T MRI scanner (Siemens Magnetom Avanto; Siemens Medical Systems, Erlangen, Germany). Each subject was placed in a supine position, with the sagittal plane perpendicular to the horizontal plane and the Frankfort plane parallel to the scanner gantry. A bite block (Dental Mouth Prop Bite Block; Shangai Carejoy Medical Co., Guangzhou, China) was used to stabilize the maximal mouth opening and minimize motion artefacts in the open mouth position. The osseous structures of the TMJ were evaluated using a 0.9-mm section thickness 3D flash T1-weighted sequence (repetition time [TR]: 21 ms, echo time [TE]: 4.95 ms, matrix: 224 × 156 pixels, voxel size: 0.9 mm × 0.9 mm × 0.9 mm, field of view: 200 mm). The articular disc was evaluated using a 1.2-mm section thickness three-dimensional proton-density (PD) weighted sequence (TR: 1200 ms, TE: 39 ms, matrix: 256 × 228 pixels, voxel size: 0.6 mm × 0.6 mm × 1.3 mm, field of view: 165 mm). OsiriX MD v. 7.5.1 software (2016; PixmeoSarl, Bernex, Switzerland) was used for the diagnostic evaluation and the linear and volumetric measurements. MRI images were examined by a radiologist with 10 years' experience, and the patients divided into three groups: ADDWR, ADDWoR, and control. ADDWR was considered the posterior band of the disc was located anteriorly to the condylar head in the closed mouth position and have normal position during the mouth opening. ADDWoR was diagnosed the disc was positioned anteriorly to the condyle both in the closed and in open mouth positions.,, Control group was accepted normal disc position to the condyle in the closed and open mouth position. All measurement was made by a dentomaxillofacial radiologist with 5 years' experience.
Disc length and disc volume
The most anterior (A) and most posterior (B) points of the disc and the midpoint of the intermediate zone (C) were noted on the sagittal PD-weighted images. The disc length was calculated as the sum of the AC and BC distances. The disc volume was measured for 5 consecutive sequences by drawing the borders of the disc in the open and closed mouth positions on the sagittal PD-weighted images [Figure 1].
|Figure 1: Drawing of the disc borders on five consecutive sagittal magnetic resonance imaging sections on the open mouth position (a-e) and three-dimensional image of the disc (f)|
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Condylar height, condylar width and condylar volume
Two circles were drawn internally in order to determine the condylar long axis on the sagittal T1-weighted images. O1 was a tangent circle that was drawn between the condylar neck and the condylar head. O2 was a tangent circle that was drawn on the narrowest region of the condylar neck. γ was the axis of the condylar neck passing through the center of the two circles. A line was drawn perpendicular to the γ, which passed from the lowest part of the sigmoid notch as the horizontal axis (x), and the line parallel to the x and tangent to the top of the condylar head was designated x'. The condylar height was calculated as the distance between x and x' (H). The condylar width was calculated by measuring the distance between the most medial and lateral points of the condyle, where the condyle was widest on the coronal T1-weighted images. The condylar volume was measured from the sigmoid notch to the top of the condyle, while drawing the borders of the condyle on the axial T1-weighted images [Figure 2].
|Figure 2: Drawing of the condyle borders on axial magnetic resonance imaging sections (a-e) and three-dimensional image of the condyle (f)|
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Articular eminence height and articular eminence inclination
The articular eminence height was measured as the perpendicular distance between the lowest point of the articular eminence and the highest point of the fossa on the sagittal T1-weighted images. The articular eminence inclination was measured by using the top-roof line method that was the angle between the Frankfort horizontal plane and the plane passing through the highest point in the roof of the glenoid fossa and the lowest point at the crest of the articular eminence on the sagittal T1-weighted images.,
The Statistical Package for the Social Sciences (SPSS 17.0 for Windows; SPSS Inc., Chicago, IL, USA) was used for the statistical analyses, and a P < 0.05 was considered to be statistically significant. According to the statistical power analysis, when considering the ratios in the ADDWR, ADDWoR, and control groups, with 95% power, at least 9 observations were required from each of these three groups. A one-way analysis of variance was used to establish the differences in the disc length, condylar height, width and volume and the articular eminence inclination, and height values with respect to the ADDWR, ADDWoR, and control groups. The differences in the disc volumes in each group with respect to the open and closed mouth position statuses were tested using the Bonferroni test. All measurements were repeated after a month, and the intraclass correlation coefficients were calculated for the intra-observer agreement. The values were interpreted as poor (<0.40), moderate (0.40–0.59), good (0.60–0.74), and excellent (≥0.75).
| Results|| |
Fifty-two TMJs with DD and 26 healthy TMJs were evaluated in this study. Most of the participants were women (84.2%), and the mean age was 26.7 ± 7 years. In the TMJs with DD, the disc volume (both in the open mouth and closed mouth positions), disc length, condylar width, and articular eminence inclination were statistically different than those values in the healthy TMJs (P < 0.05) [Table 1]. There was an association between the control group and the other two groups in terms of the disc length and condylar width (P = 0.00 and P = 0.001, respectively). In addition, there was a statistical difference between articular eminence inclination of the control and the ADDWoR group (P = 0.02) [Table 2].
|Table 1: The means of morphometric and volumetric measurements of temporomandibular joint structures in with disc displacement and healthy temporomandibular joints|
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|Table 2: Comparison of the morphometric and volumetric measurements of temporomandibular joint structures among the groups|
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The mean disc volume was greater in the control group both in the open and closed mouth positions. Moreover, the mean disc volume was greater in the open mouth position than closed mouth position in all the groups [Table 3]. There was a statistical association between disc volume and the control group and the other two groups in the closed mouth position and among the three groups in the open mouth position [Table 4].
|Table 3: The disc volume means in closed and open mouth position in the three groups|
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|Table 4: Comparison of disc volume means among the groups in closed and open mouth position|
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The intra-observer agreement was high when evaluating the reliability of the morphometric and volumetric measurements. The intraclass correlation coefficient was the highest (0.98) in the condylar volume measurements, and it was the lowest (0.92) in the disc volume measurements in the closed mouth position.
| Discussion|| |
An accurate description of the TMJ morphometry is critical to better understand the structure and function of the TMJ for the evaluation, diagnosis, and treatment of TMD. The morphometric parameters of the condyle, articular eminence and disc, have been investigated in many studies using the different types of imaging techniques. In this study, the disc volume and length of the articular disc and condyle, height and inclination of articular eminence were measured in the patients with and without DD.
MRI is an imaging technique that best shows the articular disc. However, the detection of TMJ osseous abnormalities using MRI has exhibited contradictory results. Some authors have concluded that MRI is limited in the detection of osseous changes,, there are also studies that demonstrated high sensitivity and specificity in detecting., MRI may be considered an adequate examination for the assessment of bone so that further examinations (e.g., computed tomography) that may expose patients to ionizing radiation are not required.
TMD is more common in females, but there is no consensus on the reason why. It has been found that women seek TMD treatment four to seven times more often than men, and that there may be gender or psychosocial differences in the appropriateness of seeking assistance for pain problems. Krogstad et al. reported no gender differences in the somatic complaints or anxiety in patients with TMD. Endogenous female reproductive hormones, such as estrogen, may potentially contribute to the TMD etiology. Moreover, in this study, the number of female participants was more, as in many other TMJ studies.,,,,
Both the progression and severity of degenerative bone changes in the mandibular condyle and fossa increase with age. Manfredini et al. reported a mean age of 32.7 years in patients with DD without degenerative changes, whereas the mean age of the patients with inflammatory/degenerative changes was 52.4 years. Therefore, patients aged between 18 and 40 years old were included in this study to minimize the effects of age-related degenerative changes in the bones.
Deformation of the disc increases and the disc loses its normal position with increased severity in DD.,, Cai et al. followed patients with anterior DD without treatment and the disc was more anteriorly displaced and became shorter after the follow-up. Furthermore, it was reported that the discs tended to become shorter in the ADDWoR group than in the ADDWR group. In accordance with previous studies, the highest mean disc length was found in the control group in this study, and there was a significant association between the control group and the other two groups.
Based on the studies reporting that there could be changes in the TMJ with DD, the hypothesis of this study, there may be a relationship between DD and the disc volume. Consequently, the mean disc volume was the highest in the control group and the lowest in ADDWoR group in both mouth positions. Moreover, the mean disc volume was increased in all the groups in the open mouth position when compared with the closed mouth position. Barbieri et al. found statistically significant differences between migraine patients and controls regarding the articular disc volume; however, they detected higher disc volume in DD groups than normal disc group. While the disc was expanding between the articular eminence and the condyle in the open mouth position in the ADDWR and control groups, the disc maintained its position anterior to the condyle in the ADDWoR group. Because the disc was located anterior to the condyle, the disc morphology maintained its form in the open mouth position in the ADDWoR group. The lesser disc length and disc position at the anterior of the condyle may have been the reason for the lowest disc volume in the ADDWoR group.
Degenerative changes in the condyle and articular eminence can be observed in patients with ID progression, and these changes are an indication that the ID has progressed.,, Cai et al. and Hu et al., found that the condylar height is decreased in joints with ADDWoR and DD might be accompanied by degenerative changes in the condyle. Although it was observed that the condylar height changed with DD in this study, there was no association between condylar height and among the groups. These differences may have occurred due to the different sample sizes among the studies. The lowest mean condylar width was found in the ADDWoR group in this study, which was similar to the findings of previous studies that examined the relationships between the morphometric features of the mandibular condyle and DD showed that DD was associated with narrower condyles., At a late stage of DD, disc deterioration may occur more frequently, and also bone degeneration, facial skeletal changes as the result of condylar bone loss and diminished mandibular growth secondary to DD have been reported., Therefore, our results are consistent with those reported previously, which confirm that DD can cause condylar degenerative changes.
The condylar volume may be affected by the remodelling and flattening of the condyle that can occur with DD progression because DD is commonly occur with osteoarthritis. During the course of osteoarthritis, progressive bony erosion and remodelling in the bone occur repeatedly. The repetitive condition between osseous remodelling and degenerative changes tend to change size of the condyle., In accordance with the mentioned condition, the lowest condylar volume was found in the ADDWoR group in this study, but there were no significant differences among the groups. Ahn et al. also established that the lowest condylar volume in the ADDWoR group, as well as significant differences in both the total condylar and trabecular volumes on computed tomography images. The causes of differences between the results may have been the different sample sizes and volumetric analysis programs between the studies.
The top-roof line and best-fit line methods are two different methods used to measure the articular eminence inclination and the best-fit line method is used to establish the actual condylar path; whereas the top-roof line method better shows the morphology of the articular eminence. Similar to this study, there were statistical differences with regard to the articular eminence inclination in the studies that used the top-roof line method., There is no consensus among the authors on the relationship between the articular eminence morphometry and TMD. While some authors have suggested that the inclination and flattening of the articular eminence was related to TMD,,, others have reported that the articular eminence inclination has no association., Sümbüllü et al. reported that the articular eminence height was higher in the TMD group, but there was no association. Similar to previous study, the mean articular eminence height was the lowest in ADDWoR group, and there was no statistical difference among the groups in this study. The articular eminence steepness has been examined in several studies, and the results of these studies have been controversial. Several studies have reported that a steeper articular eminence should cause ID,, while others have suggested that the articular eminence steepness decreased in the progressive ID cases., The articular eminence inclination mean was the highest in the control group and the lowest in the ADDWoR group in this study. According to these results, similar to the condyle, flattening and decreased inclination of the articular eminence might occur because of the modifications of osseous components during the osteoarthritis and during the adaptation of those components to DD progression., These discrepancies among the studies may be attributed to the different measurement methods, imaging modalities, and sample sizes.
| Conclusion|| |
The greatest limitation in this study was the low sample size. However, based on the results of this study, DD is effective in changing the morphometric and volumetric features of the condyle, articular disc, and articular eminence.
The authors kindly thank to Dr. Özgür Koşkan for assistance in the statistical analysis.
Financial support and sponsorship
This study was supported by Scientific Research Center of Suleyman Demirel University (4991-DUI-17).
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4]