Long-term haplodeficency of DSPP causes temporomandibular joint osteoarthritis in mice.

BACKGROUND: Extracellular matrix (ECM) protein malfunction or defect may lead to temporomandibular joint osteoarthritis (TMJ OA). Dentin sialophophoprotein (DSPP) is a mandibular condylar cartilage ECM protein, and its deletion impacted cell proliferation and other extracellular matrix alterations of postnatal condylar cartilage. However, it remains unclear if long-term loss of function of DSPP leads to TMJ OA. The study aimed to test the hypothesis that long-term haploinsufficiency of DSPP causes TMJ OA. MATERIALS AND METHODS: To determine whether Dspp+/- mice exhibit TMJ OA but no severe tooth defects, mandibles of wild-type (WT), Dspp+/-, and Dspp homozygous (Dspp-/-) mice were analyzed by Micro-computed tomography (micro-CT). To characterize the progression and possible mechanisms of osteoarthritic degeneration over time in Dspp+/- mice over time, condyles of Dspp+/- and WT mice were analyzed radiologically, histologically, and immunohistochemically. RESULTS: Micro-CT and histomorphometric analyses revealed that Dspp+/- and Dspp-/- mice had significantly lower subchondral bone mass, bone volume fraction, bone mineral density, and trabecular thickness compared to WT mice at 12 months. Interestingly, in contrast to Dspp-/- mice which exhibited tooth loss, Dspp+/- mice had minor tooth defects. RNA sequencing data showed that haplodeficency of DSPP affects the biological process of ossification and osteoclast differentiation. Additionally, histological analysis showed that Dspp+/- mice had condylar cartilage fissures, reduced cartilage thickness, decreased articular cell numbers and severe subchondral bone cavities, and with signs that were exaggerated with age. Radiographic data showed an increase in subchondral osteoporosis up to 18 months and osteophyte formation at 21 months. Moreover, Dspp+/- mice showed increased distribution of osteoclasts in the subchondral bone and increased expression of MMP2, IL-6, FN-1, and TLR4 in the mandibular condylar cartilage. CONCLUSIONS: Dspp+/- mice exhibit TMJ OA in a time-dependent manner, with lesions in the mandibular condyle attributed to hypomineralization of subchondral bone and breakdown of the mandibular condylar cartilage, accompanied by upregulation of inflammatory markers.

A study on volumetric change of mandibular condyles with osteoarthritis using cone-beam computed tomography.

This study aimed to quantitatively assess three-dimensional changes in the mandibular condyle with osteoarthritis using cone-beam computed tomography (CBCT). Pre- and post-treatment CBCT images of temporomandibular joints (TMJs) from 66 patients were used to assess longitudinal changes in condylar volume within individual patients using 3D slicer software. Total volume difference (dV), net increase (dV + , bone deposition), and net decrease (dV- , bone resorption) after treatment were analyzed based on clinical and radiological factors. Condyles with surface erosion at their first visit showed significantly decreased volume after treatment compared to condyles without erosion (p < 0.05). Amounts of bone resorption and deposition were higher in condyles with surface erosion (both p < 0.01). In patients with condylar erosion, the presence of joint pain was associated with a decrease in condylar volume and an increase in net resorption (both p < 0.01). When both joint pain and condylar erosion were present, patients with parafunctional habits showed reduced condylar volume after treatment (p < 0.05). Condylar volume change after treatment was negatively correlated with the duration of pain relief (R = - 0.501, p < 0.05). These results indicate that condylar erosion and TMJ pain could be significant variables affecting TMJ volume changes after treatment. Establishing appropriate treatment strategies is crucial for managing condylar erosion and TMJ pain.

[Imaging in temporomandibular joint disorders]. / Beeldvorming bij kaakgewrichtsstoornissen.

The temporomandibular joint is a unique and complex joint. Various imaging techniques have been developed to properly visualize this complex joint, such as conventional radiology, orthopantomography, CBCT and MRI. Imaging can contribute to the differential diagnosis of temporomandibular joint disorders. Common joint disorders are arthritis and internal derangement. Osseous changes of the temporomandibular joint can be clearly visualized with CBCT. MRI is superior for imaging the internal anatomy of the temporomandibular joint and is preferred in the context of internal derangement.

[Comparative evaluation of the accuracy of 3D TMJ analysis performed by different methods of processing computed tomograms]. / Sravnitel'naya otsenka tochnosti 3D-analiza elementov visochno-nizhnechelyustnogo sustava, vypolnennogo raznymi sposobami obrabotki komp'yuternykh tomogramm.

OBJECTIVE: The aim of this study. Comparison of the accuracy of segmentation of TMJ elements in different ways and assessment of the suitability of the data obtained for the diagnosis of TMJ dysfunction. MATERIALS AND METHODS: To study the segmentation of the bone elements of the TMJ (articular fossa, head of the LF), 60 computed tomograms of the maxillofacial region of patients were randomly selected in various ways (archival material). In group 1, the results of CT processing by AI diagnostics algorithms (Russia) were collected; in group 2, the results of CT processing based on the semi-automatic segmentation method in the Avantis3D program. The results of CT processing by Avantis3D AI algorithms (Russia) with different probability modes - 0.4 and 0.9, respectively, were selected for the third and fourth groups. Visually, the coincidence of the contours of the LF heads and articular pits isolated using different methods with their contours on all possible sections of the original CT itself was evaluated. The time spent on TMJ segmentation according to CT data was determined and compared using the methods described above. RESULTS: Of the 240 objects, only 7.5% of the cases showed a slight discrepancy between the contours of the original CT in group b1, which was the lowest of all. A slight discrepancy in the TMJ contours to be corrected is characteristic of the semi-automatic method of segmentation by optical density was detected in 50.4% (group 2). The largest percentage of significant errors not subject to correction was noted in the first group, which made it impossible to perform a full 3D analysis of the TMJ, and the smallest in the second and fourth. The magnitude of the error in determining the width of the articular gap in different groups is comparable to the size of one voxel per CT. When segmentation is carried out using AI, the difference between segmented objects is close to zero values. The average time spent on TMJ segmentation in group 1 was 10.2±1.23 seconds, in group 2 - 12.6±1.87 seconds, in groups 3 and 4 - 0.46±0.12 seconds and 0.46±0.13 seconds, respectively. CONCLUSION: The developed automated method for segmenting TMJ elements using AI is obviously more suitable for practical work, since it requires minimal time, and is almost as accurate as other methods under consideration.

Ultrasonographic examination of masticatory muscles in patients with TMJ arthralgia and headache attributed to temporomandibular disorders.

This study used ultrasonography to compare the thickness and cross-sectional area of the masticatory muscles in patients with temporomandibular joint arthralgia and investigated the differences according to sex and the co-occurrence of headache attributed to temporomandibular disorders (HATMD). The observational study comprised 100 consecutive patients with TMJ arthralgia (71 females and 29 males; mean age, 40.01 ± 17.67 years) divided into two groups: Group 1, including 86 patients with arthralgia alone (60 females; 41.15 ± 17.65 years); and Group 2, including 14 patients with concurrent arthralgia and HATMD (11 females; 33.00 ± 16.72 years). The diagnosis of TMJ arthralgia was based on the diagnostic criteria for temporomandibular disorders. The parameters of the masticatory muscles examined by ultrasonography were subjected to statistical analysis. The pain area (2.23 ± 1.75 vs. 5.79 ± 2.39, p-value = 0.002) and visual analog scale (VAS) score (3.41 ± 1.82 vs. 5.57 ± 12.14, p-value = 0.002) were significantly higher in Group 2 than in Group 1. Muscle thickness (12.58 ± 4.24 mm) and cross-sectional area (4.46 ± 2.57 cm2) were larger in the masseter muscle than in the other three masticatory muscles (p-value < 0.001). When examining sex-based differences, the thickness and area of the masseter and lower temporalis muscles were significantly larger in males (all p-value < 0.05). The area of the masseter muscle (4.67 ± 2.69 vs. 3.18 ± 0.92, p-value = 0.004) and lower temporalis muscle (3.76 ± 0.95 vs. 3.21 ± 1.02, p-value = 0.049) was significantly smaller in Group 2 than in Group 1. An increase in VAS was significantly negatively correlated with the thickness of the masseter (r = - 0.268) and lower temporalis (r = - 0.215), and the cross-sectional area of the masseter (r = - 0.329) and lower temporalis (r = - 0.293). The masseter and lower temporalis muscles were significantly thinner in females than in males, and their volumes were smaller in patients with TMJ arthralgia and HATMD than in those with TMJ arthralgia alone. HATMD and decreased masseter and lower temporalis muscle volume were associated with increased pain intensity.

Effect of the application of digital technology-assisted optimization in the process of adjusting jaw position.

OBJECTIVES: The aim of this study was to demonstrate a novel jaw position adjustment technique derived from digital twins and evaluate the application effect of digital technology-assisted optimization in the process of adjusting jaw position on patients with temporomandibular disorders (TMD). METHODS: A total of 74 patients with TMD who attended the Department of Temporomandibular Joint, West China Hospital of Stomatology, Si-chuan University, between June 2022 and May 2023 were selected. The patient's initial computed tomography (CT) and bilateral temporomandibular joint data obtained by magnetic resonance imaging (MRI) were collected. The 148 joints were divided into the normal disc-condyle relationship (N) group, disc displacement with reduction (DDWR) group, and disc displacement without reduction (DDWoR) group. Assisted by digital technology, the patient's CT data were reconstructed, and a personalized reference plane was established to adjust the jaw position. A three-point bite guiding splint was designed by the adjusted occlusal space and then fabricated by 3D printing technology. It was worn by the patients and then reviewed by MRI. Before and after the adjustment of jaw position, the amount and direction of condyle and disc displacement and the angle between condyle and disc were measured as the evaluation indexes of the effect of the adjustment. The correlation with condylar displacement was evaluated. RESULTS: In the N group, the disc moved backward and downward along the X and Z axes by (-0.60±0.62) and (0.51±0.71) mm, respectively. In the DDWR group, the disc moved backward and upward along the X and Z axes by (-1.33±1.38) and (-0.09±1.31) mm, respectively. In the DDWoR group, the disc moved forward and downward along the X and Z axes by (0.49±1.76) and (1.35±1.76) mm, respectively. The angle between the condyle and the disc decreased after adjustment of the jaw position in all three groups. All patients showed improvement in symptoms after adjustment. CONCLUSIONS: Digital technology-assisted jaw position adjustment can simplify the process, reduce the sensitivity of the technique, and improve patients' disc-condyle structure and symptoms. Therefore, its application in the treatment of patients with TMD is of great clinical significance.

Comparison of condylar position after free fibular flap mandibular reconstruction using computer-assisted and traditional techniques.

OBJECTIVES: To compare the changes in condylar position after mandibular reconstruction with free fibular flap(FFF) and the differences between computer-assisted techniques and traditional methods on CT images. METHODS: Thirty-four patients who underwent mandibular reconstruction with free fibular flap were selected according to the inclusion and exclusion criteria. In the 3D group, virtual surgical planning (VSP) with osteotomy cutting plate and placement guiding plate were used, while the traditional group underwent freehand reconstruction. The CT data of 68 temporomandibular joints (TMJs) were recorded before and immediately after surgery. The condylar position was evaluated by measuring the anterior space (AS), posterior space (PS) and superior space (SS), and the ln (PS/AS) was calculated according to the method proposed by Pullinger and Hollender. RESULTS: In the patients included in the 3D group, the condyle on the ipsilateral side moved slightly backward; however, in the patients in the traditional group, the ipsilateral side moved considerably anteroinferior. No obvious changes on the contralateral side were noted. In the 3D group, 33% of ipsilateral condyles were in the posterior position postoperatively when compared with the preoperative position (13%). In the traditional group, the number of ipsilateral condyles in the anterior position increased from 4 to 10, accounting for 53% postoperatively. Contrary to the traditional group, the 3D group presented less condylar displacement on the ipsilateral side postoperatively. CONCLUSIONS: This study showed a decreased percentage of change in condylar position postoperatively when VSP was used. Virtual surgical planning improved the accuracy of FFF mandibular reconstruction and made the condylar position more stable.

A Three-branch Jointed Feature and Topology Decoder guided by game-theoretic interactions for temporomandibular joint segmentation.

Segmentation of the temporomandibular joint (TMJ) disc and condyle from magnetic resonance imaging (MRI) is a crucial task in TMJ internal derangement research. The automatic segmentation of the disc structure presents challenges due to its intricate and variable shapes, low contrast, and unclear boundaries. Existing TMJ segmentation methods often overlook spatial and channel information in features and neglect overall topological considerations, with few studies exploring the interaction between segmentation and topology preservation. To address these challenges, we propose a Three-Branch Jointed Feature and Topology Decoder (TFTD) for the segmentation of TMJ disc and condyle in MRI. This structure effectively preserves the topological information of the disc structure and enhances features. We introduce a cross-dimensional spatial and channel attention mechanism (SCIA) to enhance features. This mechanism captures spatial, channel, and cross-dimensional information of the decoded features, leading to improved segmentation performance. Moreover, we explore the interaction between topology preservation and segmentation from the perspective of game theory. Based on this interaction, we design the Joint Loss Function (JLF) to fully leverage the features of segmentation, topology preservation, and joint interaction branches. Results on the TMJ MRI dataset demonstrate the superior performance of our TFTD compared to existing methods.

Provider assessment of the temporomandibular joint in Juvenile idiopathic arthritis: a retrospective analysis from the CARRA database.

BACKGROUND: Temporomandibular joint (TMJ) involvement is an often underrecognized complication of juvenile idiopathic arthritis (JIA) that can cause decreased mandibular growth, altered facial morphology, and orofacial pain. It is estimated that the TMJ is affected in 30-45% of children with JIA. Standardized physical examination and imaging evaluations are important in accurately assessing active TMJ arthritis and sequalae. Little is known about the rate at which providers evaluate TMJ involvement in their clinical practice. METHODS: Data were obtained from the Childhood Arthritis and Rheumatology Research Alliance (CARRA) Registry. Data fields related to assessment for TMJ arthritis were added in 2019. Patients were included in the study if they had a diagnosis of JIA and had data recorded between January 2020 and August 2021. Standard descriptive statistics were used to describe demographic and clinical features. RESULTS: A total of 17,761 visits were reviewed for a total of 7473 patients with JIA. A total of 52.7% of patients had maximal mouth opening (MMO) recorded as finger breadths or total incisal distance (TID). Only 8% had TID measured. A total of 5.0% had MRI with contrast performed. A total of 939 patients had a diagnosis of TMJ arthritis. Of these, 28.5% had an MRI documented, 83% had an MMO documented, and 40% had TID measured. Few patient-level characteristics were statistically related to having MMO assessed. MRI was more likely to be obtained in older and in female patients. MMO was recorded at a given visit > 80% of the time at 17 sites, and it was recorded < 1% of the time at 8 sites. MRIs were infrequently performed at all sites, with 27 sites having no MRIs obtained and only 7 sites having an MRI obtained at > 10% of visits. CONCLUSIONS: MMO is not consistently measured in patients with JIA, and it is rarely measured quantitatively. Similarly, TMJ MRIs are rarely obtained in patients with JIA. Site of care is more associated with TMJ assessments than patient-level characteristics. These data suggest that provider education is needed to improve the assessment of the TMJ in patients with JIA to enable earlier recognition and prevent long-term complications.

Quantitative and qualitative condylar changes following stabilization splint therapy in patients with temporomandibular joint disorders with and without skeletal lateral mandibular asymmetry: a cone beam computed tomographic study.

BACKGROUND: Temporomandibular disorders (TMDs) encompass pain and dysfunction in the jaw, muscles, and adjacent structures. This study aimed to explore the quantitative (condylar position, morphology) and qualitative (bone mineral density (BMD)) therapeutic outcomes following a stabilization splint (S.S.) therapy in adult patients diagnosed with TMD (Arthralgia) with/without lateral mandibular asymmetry (MA) using cone beam computed tomography (CBCT). METHODS: In this retrospective clinical study, 60 adult TMD patients who received S.S. therapy were enrolled and allocated into the TMD group (TMDG) and TMD with MA group (TMD + MAG). The diagnosis was made according to the Diagnostic Criteria for TMD (DC/TMD) AXIS I. MA was measured from the mid-sagittal plane to the Menton point. CBCT was used to scan the temporomandibular joints pre- (T0) and post- (T1)-treatment for three-dimensional analysis. Intra- and intergroup statistical comparisons were performed using the Wilcoxon signed ranks and the Kruskal‒Wallis test. RESULTS: For quantitative comparisons, there was a statistically significant difference between T0 and T1 in the joint spaces of TMD + MAG (anterior, superior, posterior, and coronal lateral on the deviated side as well as in the superior, coronal medial joint space of the contralateral side). Morphologically, the deviated side had a narrower condylar width, reduced condylar height, and a steeper eminence angle. In contrast, the contralateral side tended to have a greater condylar length. For qualitative measurements, BMD also showed statistical significance between T0 and T1 in the majority of the condyle slopes (AS, SS, PS, and LS on the deviated side and in AS and MS on the contralateral side) of TMD + MAG. Additionally, only the AS and PS showed significance in TMDG. CONCLUSION: Multiple joint space widening (AJS and CMS) and narrowing (SJS, PJS, and CLS) could characterize the deviated side in TMD + MA. Factors like narrower condylar width, reduced condylar height, and steeper eminence angle on the deviated side can worsen TMD + MA. Proper alignment of the condyle-disc position is essential for optimal function and load distribution, potentially affecting bone mineral density (BMD). MA plays a prominent role in disturbing bone densities. S.S. therapy shows more evident outcomes in TMD + MAG (on the deviated side compared to the contralateral side) than the TMDG.

Association Between Articular Eminence Structure and Joint Spaces in Temporomandibular Joints with Anterior Disc Displacement.

BACKGROUND AND AIMS: The association among the joint spaces, articular eminence morphology, and disc displacement is not well documented in the literature. This study aims to evaluate and compare the joint spaces and the articular eminence structure (eminence height [Eh] and inclination [Ei]) using cone-beam computed tomography (CBCT) of temporomandibular joints (TMJs) with anterior disc displacements and joints with normal disc position. METHODS: The study groups consisted of 75 TMJs of 39 patients. The disc status of TMJs was diagnosed with magnetic resonance imaging, and the measurements were performed on CBCT. Three groups, that is, normal disc position (NDP) group, anterior disc displacement with reduction (ADDWR) group, and anterior disc displacement without reduction (ADDWoR) group, were established. Anterior, superior, posterior joint spaces (AJS, SJS, and PJS, respectively), articular Eh, and articular Ei were measured. Statistical Package for the Social Sciences version 22 was used for statistical analysis. Shapiro-Wilk test was used to check the normality of data. Intergroup comparisons of categorical variables were assessed with Fisher-Freeman-Halton test. For comparison of continuous variables parameters, Mann-Whitney U test and Kruskal-Wallis test were used. Statistical significance level was determined as P < 0.05. RESULTS: Significant differences were not found in intergroup comparisons for PJS. However, the difference between groups was found to be significant for AJS, SJS, Eh, and Ei. Intergroup comparisons were performed for these parameters. No significant difference was found between the NDP group and the ADDWR group for AJS, SJS, Eh, and EI. The mean AJS, SJS, Eh, and Ei values in ADDWoR were found to be significantly lower compared to the corresponding values in both NDP and ADDWR groups. CONCLUSION: Decreased AJS and SJS when TMJ is evaluated with CBCT may be an indicator of ADDWoR. Authors suggest that narrowed articular Ei and reduced articular Eh can be one of the predisposing factors for anterior disc displacement.

Investigation of the accuracy of dynamic condylar position: A model study.

OBJECTIVES: To evaluate dynamic condylar positions by integrating mandibular movement recording data and cone-beam computed tomography (CBCT) and to investigate its accuracy via dynamic model experiments. METHODS: A polyvinyl chloride skull model was utilized. A robot arm was used to operate the mandible to perform mouth opening, closing, protrusion, and lateral movements. A recording device, worn on the skull, was used to record the dynamic process and an optical position tracking (OPT) system was used to simultaneously trace the movements. A self-developed software module was used to evaluate the dynamic condylar position by integrating the dynamic tracing data and a virtual skull model derived from CBCT images. Errors were defined as differences between the dynamic coordinates of six landmarks around the condylar area derived from the software module (test) and OPT system (gold standard). RESULTS: The condylar position errors were 0.76 ± 0.31, 0.55 ± 0.15, and 0.68 ± 0.23 mm for mouth opening, bilateral, and protrusion movements, respectively. Furthermore, the errors for small, moderate, and large mouth opening movements were 0.62 ± 0.19, 0.69 ± 0.29, and 0.94 ± 0.31 mm, respectively. The errors for all movements, except for large mouth opening, were significantly less than 1 mm (P < 0.05). The error was not different from 1 mm in the large mouth opening movement (P > 0.05). CONCLUSIONS: Our developed method of achieving dynamic condylar position by integrating mandibular movement recording data and CBCT images is clinically reliable. CLINICAL SIGNIFICANCE: This study proved the reliability of evaluating dynamic condylar position using a commercial dynamic recording instrument and CBCT images.

A detunable wireless resonator insert for high-resolution TMJ MRI at 1.5 T.

MRI is essential for evaluating and diagnosing various conditions affecting the temporomandibular joint (TMJ) and surrounding structures, as it provides highly detailed images that enable healthcare professionals to assess the joints and surroundings in great detail. While commercial MRI scanners typically come equipped with basic receive coils, such as the head receive array, RF coils tailored for specialized applications like TMJ MRI must be obtained separately. Consequently, TMJ MRI scans are often conducted using the head receive array, yet this configuration proves suboptimal due to the lack of specialized coils. In this study, we introduce a simple, low-cost, and easy-to-reproduce wireless resonator insert to enhance the quality of TMJ MRI at 1.5 T. The wireless resonator shows a significant improvement in signal-to-noise ratio (SNR) and noticeably better imaging quality than the head array alone configuration in both phantom and in vivo images.

Age and Gender-related Morphometric Assessment and Degenerative Changes of Temporomandibular Joint in Symptomatic Subjects and Controls using Cone Beam Computed Tomography (CBCT): A Comparative Analysis.

BACKGROUND: The temporomandibular joint diseases have been associated with various predisposing factors. Joint spaces, articular eminence height and inclination, and the shapes of the condylar and glenoid fossa have all been shown to vary in temporomandibular joint diseases (TMD) patients. Advanced imaging techniques like cone beam computed tomography (CBCT) have been employed to estimate these parameters. AIMS AND OBJECTIVES: The aim of the current study was to investigate the condylar morphology, condylar and glenoid fossa shapes, and assessment of joint spaces, such as anterior, posterior, superior, lateral, and medial spaces, through CBCT slices in coronal and sagittal planes and compare them between the control group and TMD group. MATERIALS AND METHODS: A cross-sectional study was planned where 80 joints in 40 patients were assessed for the above parameters; group I consisted of healthy patients, and group II included those with temporomandibular joint diseases (TMDs). The articular eminence height and inclination were assessed on the midsagittal section. The condylar changes and shapes of the glenoid fossa and condyles, as well as the joint spaces, were assessed on the selected coronal and sagittal sections. RESULTS: The condylar fossa had a triangular shape in the TMJ group and an oval shape in the control group. The results were highly significant (P = 0.000**). A highly significant difference in morphological parameters, such as AJS, PJS, SJS, MJS, LJS, articular eminence height, and inclination, was found between the two groups (P = 0.000**). The association of morphological parameters, such as AJS, PJS, SJS, MJS, LJS, and articular eminence height and inclination were compared with condylar and glenoid fossa shapes, where the association of superior joint space and articular eminence inclination was observed. A highly significant difference was noted between the two groups with regard to all the parameters with P=0.00*. CONCLUSION: The articular eminence inclination, as well as the superior joint space, were found to be associated with the glenoid and condyle fossa shapes in the TMJ group. These observations would, therefore, help in the early diagnosis of temporomandibular joint diseases.

The effect of tooth loss on the temporomandibular joint space: A CBCT study.

OBJECTIVE: The tooth loss has a significant impact on the positioning of the condyle in the glenoid fossa and joint spaces of the temporomandibular joint (TMJ). The aim of this study was to assess the association between tooth loss and TMJ spaces using cone beam computed tomography (CBCT) images. MATERIALS AND METHODS: This retrospective investigation involved the evaluation of CBCT images of the bilateral TMJs in a cohort of 111 individuals, comprising 68 males and 43 women. The dentition of the patients was categorized into three categories, including A (65.4%), B (19.1%), and C (16.4%), based on the Eichner index. Anterior, superior, and posterior joint spaces were then measured in sagittal views. The Kruskal-Wallis test and Mann-Whitney test were employed to identify significant differences among the three Eichner groups. RESULTS: The findings of the present study suggested that there was no statistically significant variation in the anterior joint space among different Eichner groups within the general population (p = .781). Nevertheless, the superior and posterior joint spaces exhibited statistically significant alterations, as indicated by p-values of .039 and .010, respectively. It was detected that condyles were positioned inferiorly and posteriorly in group C when compared to groups A and B. CONCLUSION: The present study indicated that greater loss of tooth-supporting zones is associated with posterior and inferior displacement of condyles. Understanding these relationships helps emphasize how crucial it is to replace missing teeth to enhance occlusion support and, in turn, stop the progression and further deterioration of temporomandibular disorders.

Imaging Evaluation of the Temporomandibular Joint.

This article describes the anatomy and function of the temporomandibular joint (TMJ), provides an overview of the various imaging modalities available for evaluating the TMJ, and discusses a variety of miscellaneous diseases that affect the TMJ.

Reliability of landmark identification for analysis of the temporomandibular joint in real-time MRI.

BACKGROUND: Real-time magnetic resonance imaging (rtMRI) is essential for diagnosing and comprehending temporomandibular joint (TMJ) movements. Current methods for tracking and analysis require manual landmark placement on each acquisition frame. Therefore, our study aimed to assess the inter- and intra-rater reliability of placing cephalometric landmarks in frames from a dynamic real-time TMJ MRI. MATERIAL AND METHODS: Four real-time MRIs of the right TMJ were taken during mandibular movement at ten frames per second. Seven dentists identified ten landmarks on two frames (intercuspal position-ICP-and maximum mouth opening-MMO) twice at a two-week interval, yielding 112 tracings. Six typical cephalometric measurements (angles and distances) were derived from these landmarks. The reliabilities of landmarks and measurements were evaluated using distance-based (dbICC), linear mixed effect model intraclass correlation (lmeICC), and standard ICC. RESULTS: The average inter-rater reliability for the landmarks stood at 0.92 (dbICC) and 0.93 (lmeICC). The intra-rater reliability scores were 0.97 and 0.98. Over 80% of the landmarks showed an ICC greater than 0.98 (inter-rater) and over 0.99 (intra-rater). The lowest landmark ICC was observed for the orbitale and the oblique ridge of the mandibular ramus. However, the cephalometric angle and distance measurements derived from these landmarks showed only moderate to good reliability, whereas the reliability in the frames with ICP was better than those with MMO. Measurements performed in the ICP frame were more reliable than measurements in the MMO frame. CONCLUSION: While dentists reliably localize isolated landmarks in real-time MRIs, the cephalometric measurements derived from them remain inconsistent. The better results in ICP than MMO are probably due to a more familiar jaw position. The higher error rate of the TMJ measurements in MMO could be associated with a lack of training in real-time MRI analysis in dentistry.

The linear intra-articular motions of the temporomandibular joint in individuals with severe forward head posture: A cross-sectional study.

BACKGROUND: The cervical vertebrae and the temporomandibular joint (TMJ) may be linked through their common muscles. OBJECTIVES: The aim of the present study was to compare the linear intra-articular motions of the TMJ between individuals with the normal craniocervical posture (CCP) and severe forward head posture (FHP). DESIGN: Cross-sectional study. METHODS: Volunteers (N = 38) were equally assigned to either the severe FHP group or the normal CCP group according to their craniovertebral angle (CVA). The CVA angles greater than 49° were considered as the normal CCP while angles between 44 and 40° were regarded as the severe FHP. The TMJ was imaged at the closed, median, and maximum open positions of the mouth using an ultrasound machine with a 7.5 MHz linear transducer in the sitting position. The best-fitting curve in the contour registration method was employed to measure displacement of the mandibular condyle on the transverse and vertical axes. RESULTS: The forward displacement of the mandibular condyle in the severe FHP group was significantly (p-value = 0.037) reduced compared to the normal CCP group at maximum open position of the mouth, while no significant difference was revealed at closed (p-value = 0.937) or median open (p-value = 0.699) positions. The perpendicular displacement of the mandibular condyle exhibited no significant (p-value>0.107) difference between groups at any mouth position. DISCUSSION: The current study demonstrated, for the first time, that severe FHP may impact the intra-articular motion of the TMJ. This study presumed that individuals with severe FHP may encounter a force imbalance in the anterior-posterior direction.

Diagnostic accuracy of MRI-CBCT fused images in assessment of clinically diagnosed internal derangement of the temporomandibular joint.

OBJECTIVES: To evaluate the diagnostic accuracy of Fused (MRI)-CBCT images in the assessment of internal derangement of the temporomandibular joint. METHODS: MRI and CBCT images of the TMJ were evaluated bilaterally in 10 patients with clinically diagnosed internal derangement. Image fusion was performed using Amira 3D Software (version 5.4.3, Thermo Fisher Scientific Inc.). RESULTS: The AUC index for MRI-CBCT fused images was 0.83, which was significantly different from the null hypothesis value of 0.5. This was confirmed by inter-examiner reliability index of 0.87, which is statistically significant. CONCLUSION: MRI-CBCT fused images can significantly improve the accuracy and inter-examiner reliability in the evaluation of clinically diagnosed cases with internal derangement.

Comparison of CBCT radiation doses with conventional radiographs in TMJ imaging using Monte Carlo simulations.

Three-dimensional imaging methods are widely used for evaluation of bony changes of temporomandibular joint (TMJ). Besides, lateral and posterio-anterior TMJ projections in both closed- and open-jaw positions for each temporomandibular joint are used as two-dimensional diagnostic tools. The purpose of the present study was to compare effective and mean organ absorbed doses of plain radiography techniques with those of different modalities of cone beam computed tomography (CBCT) scanning of an adult's temporomandibular joint. PCXMC 2.0 software was used to calculate mean organ and effective doses. A NewTom CBCT device (Newtom 5G XL; QR systems; Verona, Italy) was simulated at 360° rotation using a 6 × 6 cm2 FOV in standard and high-resolution modes. Lateral and posterio-anterior TMJ plain projections were simulated according to recommendations of the manufacturer of the Planmeca ProMax® 2D S3 device. Doses for both projections were simulated with Monte Carlo methods and the International Commission on radiological protection adult reference computational phantoms. The highest mean organ absorbed doses occurred in bone surfaces, salivary glands, and skull for posterio-anterior TMJ and lateral TMJ, and for CBCT scanning in all examinations. The effective doses of posterio-anterior and lateral TMJ plain radiographs were found to be higher than those of the Standard Mode-Eco Scan CBCT. Therefore, the lowest effective dose was calculated in Standard Mode-Eco Scan CBCT. It is concluded that NewTom 5G XL Standard Mode-Eco Scan CBCT can be used instead of plain radiographs (lateral and posterio-anterior TMJ) in temporomandibular joint imaging as it allows visualizing the three-dimensional structure of the temporomandibular joint as an advantage.