Temporomandibular Joint Components Research Articles

The Stress Effects of Mandibular Movements on the Temporomandibular Joint With Sagittal Split Ramus Osteotomy.

The aim of this study was to evaluate the stress changes in the temporomandibular joint (TMJ) after sagittal split ramus osteotomy (SSRO) with finite element analysis (FEA). 5 and 10mm mandibular setback and advancement were applied to models by using SSRO and a control model without osteotomy evaluated. The articular disc was modeled as superelastic, and the stresses on the articular fossa, disc, and condyle were evaluated. The stresses on the cartilage were 1.150 MPa on the 5mm advancement model and 1.506 MPa on the 10mm advancement model. The stresses on the disc were 11.56 MPa on the 5mm advancement model, 7.94 MPa on the 10mm advancement model and the amount were significantly higher than other models. The stress, especially in the cartilage, increased with the amount of advancement. In the setback models, the stresses on the condylar cartilage and the disc were higher than in the control model, and the stress in the condylar cartilage increased with the amount of setback. SSRO increases the stresses in the TMJ components and stresses increase depending on the amount of advancement and setback and may cause the development of joint problems.

Multi-class segmentation of temporomandibular joint using ensemble deep learning

Temporomandibular joint disorders are prevalent causes of orofacial discomfort. Diagnosis predominantly relies on assessing the configuration and positions of temporomandibular joint components in magnetic resonance images. The complex anatomy of the temporomandibular joint, coupled with the variability in magnetic resonance image quality, often hinders an accurate diagnosis. To surmount this challenge, we developed deep learning models tailored to the automatic segmentation of temporomandibular joint components, including the temporal bone, disc, and condyle. These models underwent rigorous training and validation utilizing a dataset of 3693 magnetic resonance images from 542 patients. Upon evaluation, our ensemble model, which combines five individual models, yielded average Dice similarity coefficients of 0.867, 0.733, 0.904, and 0.952 for the temporal bone, disc, condyle, and background class during internal testing. In the external validation, the average Dice similarity coefficients values for the temporal bone, disc, condyle, and background were 0.720, 0.604, 0.800, and 0.869, respectively. When applied in a clinical setting, these artificial intelligence-augmented tools enhanced the diagnostic accuracy of physicians, especially when discerning between temporomandibular joint anterior disc displacement and osteoarthritis. In essence, automated temporomandibular joint segmentation by our deep learning approach, stands as a promising aid in refining temporomandibular joint disorders diagnosis and treatment strategies.

Metabolic profiling of synovial fluid in human temporomandibular joint osteoarthritis.

Temporomandibular joint (TMJ) osteoarthritis (OA) is a common TMJ degenerative disease with an unclear mechanism. Synovial fluid (SF), an important component of TMJ, contains various proteins and metabolites that may directly contribute to OA. The present study aimed to investigate the influence of SF in TMJOA at the metabolite level. Untargeted and widely targeted metabolic profiling were employed to identify metabolic changes in SF of 90 patients with different TMJOA grades according to TMJ magnetic resonance imaging. A total 1498 metabolites were detected. Most of the metabolites were amino acids and associated metabolites, benzene and substituted derivatives, and lipids. Among patients with mild, moderate and severe TMJOA, 164 gradually increasing and 176 gradually decreasing metabolites were identified, indicating that biosynthesis of cofactors, choline metabolism, mineral absorption and selenocompound metabolism are closely related to TMJOA grade. Combined metabolomics and clinical examination revealed 37 upregulated metabolites and 16 downregulated metabolites in patients with pain, of which 19 and 26 metabolites were positively and negatively correlated, respectively, with maximum interincisal opening. A model was constructed to diagnose TMJOA grade and nine biomarkers were identified. The identified metabolites are key to exploring the mechanism of TMJOA. In the present study, a metabolic profile was constructed and assessed using a much larger number of human SF samples from patients with TMJOA, and a model was established to contribute to the diagnosis of TMJOA grade. The findings expand our knowledge of metabolites in human SF of TMJOA patients, and provide an important basis for further research on the pathogenesis and treatment of TMJOA.

Relationships between functional temporomandibular joint space and disc morphology, position, and condylar osseous condition in patients with temporomandibular disorder.

To investigate the correlations between joint space and temporomandibular joint (TMJ) components and the compressive states of the disc and condyle subsequent to joint space changes. A total of 240 TMJs were categorized according to disc morphology, disc position, and condylar osseous condition. The two-dimensional (2D) and three-dimensional (3D) measurements were compared. The functional joint space (FJS) and disc areas on closed- and open-mouth images (DA-C and DA-O) were also calculated, and the joint space was measured in five directions. Different groups of TMJ components were compared. A spring model was used to simulate the effect of condylar displacement on the disc and condyle. Disc morphology was strongly correlated with its position. The measurements were equivalent between 2D and 3D methods. DA-C and FJS differed significantly between groups. The DA-C to FJS ratio differed between the Class 2 and Class 3 groups and between disc displacement groups with and without reduction. Altered disc morphology and position were correlated with significant changes in joint space in the 60°, 90°, and 120° directions. Despite minor discrepancies among condylar osseous conditions, reduced joint space was correlated with bone destruction at the corresponding site. The spring model stimulation revealed that condylar displacement caused elevated stresses on the disc and condyle. Condylar displacement causes joint space alterations while exerting compressive pressure on both the disc and condyle. Proper condylar positioning within the fossa is recommended to ensure sufficient articular disc accommodation.

Evaluation of Rheumatic Diseases Affecting the Temporomandibular Joint: A Cone Beam Computed Tomography Study and Literature Review.

Due to the silent manifestation of temporomandibular joint (TMJ), dentists and rheumatologists may neglect treatment for this joint. The aim of this study was to investigate the TMJ components in patients with various rheumatic diseases and to compare them with a control group based on cone beam computed tomography (CBCT) images. This study comprised an assessment of the CBCT images of 65 patients (130 temporomandibular joints) with various rheumatic diseases (mostly rheumatoid arthritis) affecting the TMJ. Moreover, 65 patients (130 temporomandibular joints) with a similar age and gender distribution were examined as the control group. Pathologies were classified into a total of 12 types for the presence of any osseous changes in the condylar head or articular fossa or for joint space narrowing. Statistical analysis of all data was performed with SPSS version 18. The conformity of continuous variables to a normal distribution was examined by the Kolmogorov-Smirnov test. The Mann-Whitney U test was used to compare the means of two independent groups. The Pearson Chi-square test, Yates correction and Fisher's exact test were used in the analysis of categorical variables. The mean age of the patient and control groups was 50 ± 13 and 48 ± 16, respectively, and no statistically significant difference was found between the patient and control groups in terms of age distribution (p = 0.123). Condylar erosion, condylar flattening, subcondylar sclerosis, osteophytes, subcortical cysts, articular eminence resorption and articular eminence flattening rates were found to be statistically significantly higher in the patient group than in the control group (p < 0.05). Dentomaxillofacial radiologists should examine the bony components of the TMJ in patients with rheumatic diseases, and a multidisciplinary approach involving a dental specialist and rheumatologist is required.

Volumetric differences in temporomandibular joint components in patients with facial asymmetry: A 3D tomographic segmentation study

PurposeTo determine if there are differences in condylar volume, glenoid cavity and joint space between patients diagnosed with facial asymmetry (FA), between affected and contralateral sides and with respect to subjects without FA. MethodsCross-sectional, retrospective study comparing CT/CBCT images from patients with FA diagnosis referred to a private clinic, versus a control group, age and sex matched, of patients requiring orthodontic treatment without FA. The 3D Slicer software was used for the analysis. Bivariate analysis was performed to compare qualitative variables using Chi-square or Fisher tests, and for normal distribution quantitative variables, the t-student test was used. The level of significance was p < 0.05. ResultsThe FA group (n = 138) included: Hemimandibular Elongation (HE) (n = 64), Hemimandibular Hyperplasia (HH) (n = 12), Hybrid Form (HF) (n = 20), Asymmetric Mandibular Prognathism (AMP) (n = 25), Glenoid Cavity Asymmetry (GCA) (n = 9) and Functional Laterognathism (FL) (n = 8). The control group (n = 20) had no FA and no signs or symptoms of temporomandibular dysfunction. The right condylar and glenoid cavity volumes were significantly larger in FA cases. The volumes of the right and left joint space had significant differences only in HE patients. ConclusionCondylar volumes are higher in almost all FA subgroups compared to matched controls. The glenoid cavity volume is larger in FA patients, except for the GCA right and FL left sides. Regarding articular spaces, HE was the only entity with less volume on the contralateral side. The evaluation of structural volume by 3D-CT images helps to diagnose and differentiate FA subgroups.

Impact of molar teeth distalization by clear aligners on temporomandibular joint: a three-dimensional study

BackgroundMaxillary molar distalization is a common technique used in the non-extraction treatment of Angle Class II malocclusion that can effectively correct the molar relationship and create spaces for anterior teeth alignment. However, this approach may also impact the temporomandibular joint (TMJ) due to predictable changes in the posterior vertical dimension. Despite its widespread use, Class II malocclusions correction by molar distalization with clear aligners has not been investigated for their effects on the TMJ. Therefore, this study aimed to analyze the impact of sequential molar distalization using clear aligners on the TMJ.MethodsThree-dimensional CBCT scans of 23 non-growing patients (7 males, 16 females; mean age 29.8 ± 4.6 years) with skeletal class I or II malocclusion and a bilateral molar class II relationship treated by sequential upper molars distalization with orthodontic clear aligners (Invisalign, Align Technology, San Josè, Ca, USA). A total of 46 joints were examined before and after molar distalization using Anatomage InvivoDental 6.0.3. Linear and angular measurements of the mandibular joint were measured, including joint parameters, inclination, position, and the dimension of the condyle and articular fossa. In addition, 3D volumetric spaces of the joint were analyzed. All data were statistically analyzed by paired T test to determine the differences between the pre-and post-orthodontic procedures.ResultsNo statistically significant differences were found in all primary effects resulting from maxillary molars distalization by clear aligners on TMJ components measurements and joint spaces between T0 and T1. Meanwhile, statistically significant differences were observed in the linear position of the upper molars and the molar relationship parameter with at least P ≤ 0.05.ConclusionTreatment by sequential upper molars distalization with clear aligners does not lead to significant TMJ parameters changes in condyle and fossa spaces, dimensions, and positions.

Evaluation of temporomandibular joint changes seen in pre-operative and post-operative patients of oral submucous fibrosis using MRI: A prospective study

To evaluate alterations in temporomandibular joint due to immobilisation and re-mobilisation in oral submucous fibrosis patients. The study population included 2 groups, patients and normal – 22 TMJ’s of 11 individuals respectively. MRI was performed on all patients pre-operatively and 5 month post-operatively and also on controls. Disc thickness (anterior, intermediate and posterior zone), disc length, joint space and structural changes in the glenoid fossa and condylar head were assessed in all the MRI scans. The severity of changes in relation to duration of reduced mouth opening was noted. And, finally regeneration potential of the TMJ after remobilizing the jaw, on 5th month POD was observed. All the measurements were tabulated and subjected to statistical analysis. The study showed that there were significant differences in the pre-op and normal. The post treatment values/dimensions were comparatively the same as that of the normal population (except for joint space on right side and disc length on left side, which is negligible). It proves that the treatment makes the condition comparably similar to that of normal dimension over a time period of 5 months, sighting the potential capacity of the TMJ to regenerate and repair. The study revealed statistically highly significant changes in the components of Temporomandibular joint in OSMF patients with varying degrees of restriction in mouth opening when compared to controls, and return of the joint structurally towards recovery at 5 month POD stresses upon the need for an early intervention.

The effect of myotonic dystrophy type 1 on temporomandibular joint and dentofacial morphology: A CBCT analysis.

Myotonic dystrophy type 1 (DM1) is a neuromuscular multisystem disease. Early involvement of facial muscles may produce an extra load on the temporomandibular joint (TMJ) in DM1. This study aimed to investigate the morphological analyses of the bone components of temporomandibular joint (TMJ), and dentofacial morphology in myotonic dystrophy type 1 (DM1) patients by cone-beam computed tomography (CBCT). Sixty-six individuals (33 DM1, and 33 healthy subjects) age ranging from 20 to 69 were included in the study. Clinical examinations of the patients' TMJ regions and evaluation of dentofacial morphology (maxillary deficiency, open-bite, deep palate and cross-bite) were performed. Dental occlusion was determined based on Angle's classification. CBCT images were evaluated regarding mandibular condyle morphology (convex, angled, flat and round) and osseous changes observed in the condyle (normal, osteophyte, erosion, flattening, sclerosis). DM1-specific morphological and bony TMJ alterations were determined. DM1 patients showed a high prevalence of morphological and osseous TMJ changes, and statistically significant skeletal alterations. The analysis of CBCT scans indicated the prevalent condylar shape among patients with DM1 was flat, the main osseous abnormality was flattening, there was a tendency towards skeletal Class II and a posterior cross-bite was frequently detected in DM1 patients. There was no statistically significant difference between the genders on the parameters evaluated in both groups. Adult patients with DM1 presented a high frequency of crossbite, tendency to skeletal Class II and morphological osseous alterations of TMJ. The analysis of the morphological condylar alterations in patients with DM1 may be beneficial in the diagnosis of TMJ disorders. This study reveals DM1-specific morphological and osseous TMJ alterations to provide an appropriate orthodontic/orthognathic treatment planning to patients.

Explainable deep learning-based clinical decision support engine for MRI-based automated diagnosis of temporomandibular joint anterior disk displacement

Background and Objective: MRI is considered the gold standard for diagnosing anterior disc displacement (ADD), the most common temporomandibular joint (TMJ) disorder. However, even highly trained clinicians find it difficult to integrate the dynamic nature of MRI with the complicated anatomical features of the TMJ. As the first validated study for MRI-based automatic TMJ ADD diagnosis, we propose a clinical decision support engine that diagnoses TMJ ADD using MR images and provides heat maps as the visualized rationale of diagnostic predictions using explainable artificial intelligence. Methods: The engine builds on two deep learning models. The first deep learning model detects a region of interest (ROI) containing three TMJ components (i.e., temporal bone, disc, and condyle) in the entire sagittal MR image. The second deep learning model classifies TMJ ADD into three classes (i.e., normal, ADD without reduction, and ADD with reduction) within the detected ROI. In this retrospective study, the models were developed and tested on the dataset acquired between April 2005 to April 2020. The additional independent dataset acquired at a different hospital between January 2016 to February 2019 was used for the external test of the classification model. Detection performance was assessed by mean average precision (mAP). Classification performance was assessed by the area under the receiver operating characteristic (AUROC), sensitivity, specificity, and Youden’s index. 95% confidence intervals were calculated via non-parametric bootstrap to assess the statistical significance of model performances. Results: The ROI detection model achieved mAP of 0.819 at 0.75 intersection over union (IoU) thresholds in the internal test. In internal and external tests, the ADD classification model achieved AUROC values of 0.985 and 0.960, sensitivities of 0.950 and 0.926, and specificities of 0.919 and 0.892, respectively. Conclusions: The proposed explainable deep learning-based engine provides clinicians with the predictive result and its visualized rationale. The clinicians can make the final diagnosis by integrating primary diagnostic prediction obtained from the proposed engine with the patient’s clinical examination findings.

Evaluation of condyle-fossa relationships in skeletal Class I malocclusion with variable degrees of deep overbite and open bite

ABSTRACT Objective To compare the temporomandibular joint (TMJ) position and shape between skeletal Class I subjects with different degrees of deep overbite or open bite and unaffected peers. Methods Cone beam computed tomography (CBCT) images of 90 participants, equally divided into deep bite, open bite, and control groups (DBG, OBG, and CG, respectively), were analyzed. The DBG and OBG were further subdivided into three subgroups based on the severity. Linear and angular measurements were used to determine the positional and morphological characteristics of the TMJ. Results DBG showed significantly larger superior joint space, anterior inclination of the condyle, and articular eminence inclination than CG and OBG. The severity of deep bite and open bite significantly influenced the TMJ position and morphology. Conclusion In severe deep overbite and open bite cases, there were considerable alterations in TMJ components, most likely as a result of functional demands.

Three-Dimensional Assessment of the Temporomandibular Joint Changes Following Reversed Twin Block Therapy of Patients With Skeletal Class III Malocclusion in Conjunction With the Photobiomodulation Therapy: A Randomized Controlled Clinical Trial.

Background: Despite the positive effect of the photobiomodulation therapy (PBMT) application on animals, the primary role of this technique on the human condyle is still unclear. Several experimental reports have shown the efficacy of PBMT in inducing cellular changes in the temporomandibular joint (TMJ) region during functional treatment of patients with skeletal deformities. Still, the lack of information about its effects on human condyles requires further studies.Objectives: This study aimed to evaluate the effect of PBMT on the TMJ components following Class III treatment with the reversed twin block (RTB) appliance in growing patients. Materials and Method: Forty children (12 females, 28 males) between the age of nine and eleven years with skeletal Class III were assigned randomly to the RTB group with photobiomodulation (RTB+PBMT) or the control group (RTB). The PBMT was applied to the TMJ region using an 808-nm wavelength Ga-Al-As semiconductor laser device with 5 Joules/cm2 energydensity on days 1, 3, 7, and 14 of the first month. Afterwards, the irradiation was conducted every 15 days until the end of the treatment. Cone-beam computerized tomography (CBCT) images were taken before (T1) treatment and following the end of treatment (T2) to assess TMJ and skeletal changes.Results: Condylar volume was significantly increased in the RTB group only by a mean of 287.97 mm3 (p<0.001). The significantly backward and upward condylar movement was observed in the RTB and RTB+PBMT groups (superior joint space (SJS): 0.26 mm, 0.15 mm; posterior joint space (PJS): 0.42mm, 0.11mm, respectively). The RTB group showed the most remarkable changes. Significant improvement of the sagittal maxilla-mandibular relationship was greater in the RTB+PBMT group compared to the RTB group (p=0.02).Conclusion: There were no considerable differences in the condylar position after Class III treatment between the RTB and the RTB+PBMT groups. But a difference in the condylar volume was noticed between the two group.

Effects of cleft lip and palate on temporomandibular joint components: a CBCT study

Introduction: To assess the effects of cleft lip and palate (CLP) on the temporomandibular joint (TMJ) components using cone-beam computed tomography (CBCT). Methodology: This historical cohort study evaluated 20 CBCT scans of the TMJ area of patients with unilateral CLP as the test group and 20 CBCT scans of the TMJ area of non-CLP controls with class I occlusion. The morphological properties and dimensions of the condyle, the thickness of the glenoid fossa and articular eminence, and the articular eminence angle were measured and recorded. The two groups were compared regarding the above-mentioned variables by the Chi-square or t test (alpha=0.05). Results: The left and right axial condylar angles in CLP patients were significantly lower than the corresponding values in the control group by 1.8 degrees in the left and 2 degrees in the right side (p=0.005). The mediolateral condylar dimension at both sides was significantly lower in CLP patients than in the controls (p=0.001). The differences between the two groups were not significant in the anteroposterior condylar dimension, glenoid fossa thickness, and articular eminence thickness (p&gt;0.05). The CLP patients had significantly lower articular eminence angle in the right side (p=0.016) but not in the left side (p&gt;0.05), compared with the controls. Conclusion: Unilateral CLP patients have lower axial condylar angle and mediolateral condylar dimension at both sides, and lower articular eminence angle in the right side than the controls.

Effects of cleft lip and palate on temporomandibular joint components: a CBCT study

Introduction To assess the effects of cleft lip and palate (CLP) on the temporomandibular joint (TMJ) components using cone-beam computed tomography (CBCT). Methodology This historical cohort study evaluated 20 CBCT scans of the TMJ area of patients with unilateral CLP as the test group and 20 CBCT scans of the TMJ area of non-CLP controls with class I occlusion. The morphological properties and dimensions of the condyle, the thickness of the glenoid fossa and articular eminence, and the articular eminence angle were measured and recorded. The two groups were compared regarding the above-mentioned variables by the Chi-square or t test (alpha=0.05). Results The left and right axial condylar angles in CLP patients were significantly lower than the corresponding values in the control group by 1.8 degrees in the left and 2 degrees in the right side (p=0.005). The mediolateral condylar dimension at both sides was significantly lower in CLP patients than in the controls (p=0.001). The differences between the two groups were not significant in the anteroposterior condylar dimension, glenoid fossa thickness, and articular eminence thickness (p&gt;0.05). The CLP patients had significantly lower articular eminence angle in the right side (p=0.016) but not in the left side (p&gt;0.05), compared with the controls. Conclusion Unilateral CLP patients have lower axial condylar angle and mediolateral condylar dimension at both sides, and lower articular eminence angle in the right side than the controls.

Recovery of Post-Traumatic Temporomandibular Joint after Mandibular Fracture Immobilization: A Literature Review

Considered as one of the most common traumatic injuries of the maxillofacial region, mandibular fractures remain among the complex causes of temporomandibular joint disorders (TMDs). Due to the complexity of the temporomandibular joint, the management of TMDs represents a challenge in real-life practice; although many treatment modalities have already been proposed, ranging from conservative options to open surgical procedures, a consensus is still lacking in many aspects. Furthermore, despite continuous improvement of the management of mandible fractures, the duration of immobilization and temporary disability is not reduced, and the incidence of complications remains high. The aim of the present study is to (i) review anatomophysiological components of temporomandibular joint; (ii) review concepts of temporomandibular joint fractures; and (iii) describe methods of the recovery of the temporomandibular joint after mandibular fracture immobilization.

Evaluation of condylar changes in relation to various malocclusions

Introduction: Variability in the size and shape of mandibular condyles among individuals of different sexes and ages may appear as a remodeling process to accommodate malocclusion. Hence, the aim of this study was to assess whether or not associations exist between different types of malocclusions and morphological modifications of the mandibular condyle. Materials and Methods: A systematic literature search was conducted on the Medline database via PubMed interface and supplemented by a manual search via Google Scholar to identify more articles reporting the subject of the review. A combination of controlled vocabulary was used in the search strategy and the final update was stopped on January 2021. The risk of bias was assessed based on the Newcastle–Ottawa Scale. Results and Discussion: Considering the preestablished inclusion and exclusion criteria, 20 articles were retained with 2607 human subjects (967 males/1299 females and 341 not specified, age: 4–60 years). Eighty percent of the selected articles reported associations between malocclusion and morphological changes of the condylar head. Sagittal plane malocclusions produce more changes to the temporomandibular joint components (head of condyle and joint space) (71.93%), while vertical malocclusions lead to the most severe manifestations. Conclusions: Cone-beam computed tomography is the most useful tool for the assessment of osseous morphology of mandibular head condyles and detection of cortical erosion (21.7%). Associations between morphological changes of the condylar head and specific types of malocclusions were proven. However, there is still a need for more clinical studies.

Initial radiological signs of dentofacial deformity in juvenile idiopathic arthritis

Juvenile idiopathic arthritis (JIA) is the most common rheumatic disease in childhood and the temporomandibular joint (TMJ) is often involved. TMJ arthritis in growing individuals can cause deformation of facial skeleton (dentofacial deformity) and TMJ components (TMJ deformity). Treatment outcome hinges on early initiation of anti-inflammatory treatment and orthopaedic treatment with dental splints. The aim of the present study was to characterize the radiological signs of dentofacial deformity in patients with a JIA-induced need for orthopaedic treatment. We retrospectively studied 96 patients with JIA and 20 non-JIA controls to identify the initial radiological signs of JIA-induced dentofacial deformity leading to initiation of orthopaedic treatment. We found that initial radiological signs of dentofacial deformities were subtle and characterized by minor mandibular asymmetry and occlusal plane steepening. Radiological findings of TMJ deformity associated with initial dentofacial deformity were frequent and characterized by condylar articular surface flattening (OR 8.42), condylar subcortical cyst (OR 5.94), condylar surface erosion (OR 5.38) and condylar deviation in form (OR 25.39). Radiological signs of TMJ deformity were also documented in TMJs considered “healthy” during initial clinical and radiological examination. This study presents new knowledge of importance for early diagnosis of dentofacial deformity in JIA. Early diagnosis of dentofacial deformity is important as treatment outcome is greatly influenced by timely initiation.

Contemporary Imaging Modalities for Temporomandibular Joint

There are different imaging methods used in the evaluation of bone structure, disc, ligaments and muscles that make up Temporomandibular Joint (TMJ). The aim of this review is give information about choice of suitable imaging methods for TMJ diseases from past to present. In the past, conventional radiographs have often been used for TMJ imaging, but nowadays magnetic resonance imaging is the gold standard for soft tissue imaging and disc position determination. Another new technology, ultrasonography can be used for disc displacement, effusion, diagnosis of intraarticular defects. Cone beam computed tomography, it is used for the evaluation of cortical and trabecular structure of bone components of TMJ, developmental anomalies and traumatic injuries affecting TMJ, pathological changes such as osteophyte, erosion, fractures, ankylosis, glenoid fossa-condyle relationship. Nowadays, in parallel with the developing technology, a single imaging method is not used for TMJ imaging and evaluation is performed with several imaging methods. Imaging methods should be selected by evaluating the factors such as radiation dose, contribution to diagnosis and treatment plan, easy applicability.

Risk Factors Associated With Poor Outcomes Following Temporomandibular Joint Discectomy and Fat Graft

Temporomandibular joint (TMJ) discectomy is performed for patients with degenerative joint disease with an unsalvageable disc, but with a salvageable condylar head and glenoid fossa. The purpose of this study was to estimate the incidence and risk factors associated with poor postoperative outcomes following TMJ discectomy and abdominal fat grafting. A retrospective cohort study was conducted on patients who underwent TMJ discectomy. Included in this study were patients who had complete data sets with a minimum of 1-year follow-up. Potential risk factors included demographics, preoperative findings (mouth opening, pain levels, previous TMJ surgery), operative findings (disc degeneration, state of TMJ components), and postoperative outcomes (pain levels, mouth opening). Failed outcomes were those who had return of pain postoperatively, no improvement in mouth opening following TMJ discectomy, and/or those who progressed to TMJ total joint replacement (TJR). Statistical methods included Kaplan-Meier curves and Cox proportional hazards regression time to event analyses. This study included 129 patients who had undergone 132 TMJ discectomies. Most patients were female (89.9%), with a mean age of 43.2 years, standard deviation 14.2. The success rate for discectomy was 75.2% and the conversion rate of TMJ discectomy to TJR was 11.7%. A total of 32 patients (24.8%) experienced return of pain. The median time to return of pain or second surgery was 94.4 months (95% CI=88.3 to 101.8). No risk factors were statistically significant, although mouth opening improvement of less than 10% was associated with higher risk of poor outcome (P=.77). The findings of this study suggest that lower improvement in mouth opening at 1 year following surgery is likely to result in failure of the TMJ discectomy procedure although the result was not statistically significant. This outcome may ultimately necessitate a TJR.

Magnetic Resonance Imaging and Cone Beam CT Image Registration for Osseous and Soft Tissue Abnormalities of Temporomandibular Joint: A Systematic Review

Abstract Introduction Proper diagnosis of temporomandibular disorders (TMDs) is paramount for proper management. Cone beam computed tomography (CBCT) provides additional information about osseous components of TMJ, but diagnosis of soft tissue abnormalities is still a challenging issue for the clinicians. To overcome this, magnetic resonance imaging (MRI) and CBCT registration has shown to be a new promising technique that combines key features of both images into one single fusion image. The purpose of this systematic review was to compile available literature regarding the usefulness of CBCT and MRI-CBCT fusion imaging in proper diagnosis of temporomandibular joint (TMJ) abnormalities. Materials and Methods Computerized literature search from January 2010 to 2020 using five databases: PubMed (MEDLINE) database (National Library of Medicine, NCBI), Cochrane Database, Scopus, Embase, and Science Direct was conducted by use of medical specific headings (MeSH) keywords. Results Only 10 articles met the inclusion criteria. Eight articles showed that CBCT accurately detected osseous components of TMJ but has low reliability in diagnosing soft tissue articular disc disorders. Relationship between hard and soft tissues were clearly visualized in fused images. Conclusion MRI-CBCT image registration is a reliable diagnostic tool for simultaneous evaluation of osseous and soft tissue abnormalities of TMJ and in future more studies should be encouraged to validate its accuracy for TMJ analysis.