Size, shape and age-related changes of the mandibular condyle during childhood

CT data analysis of temporomandibular joint morphology in patients with Open-mouth breathing

OBJECTIVE

This study aims to investigate the correlation between open-mouth breathing and temporomandibular joint morphology by examining CT data in patients.

METHODS

From January to December 2022, 31 patients with open-mouth breathing and 20 with normal breathing were chosen from those attending the Stomatological Hospital of Chongqing Medical University. We compared condylar measurements among normal breathers (NB), pre-operative open-mouth breathers (Pre-OB), and post-operative open-mouth breathers (Post-OB) to identify statistically significant differences.

RESULTS

Upon comparing the measurement parameters of the NB with the Pre-OB, we found significant statistical differences in the bilateral condylar height, depth of the articular fossa, anterior joint space, and the anterior inclined plane length of the condyle (p < 0.05).Further examination of the Pre-OB, when considering duration of open-mouth breathing, revealed pronounced differences in the condylar mediolateral diameter, fossa depth, anterior joint space, condylar height, and the condyle's horizontal angle (p < 0.05).Regarding the A/N ratio, it showed no significant correlation with the preoperative oral breathing group. Lastly, compared with Pre-OB, Post-OB highlighted a distinct statistical increase in the anterior slope length of the condyle (p < 0.05).

CONCLUSION

A discernible correlation between open-mouth breathing and condylar morphology exists. Continuous open-mouth breathing contributes to adaptive changes in the condylar morphology. Although limited post-operative data suggests that halting open-mouth breathing doesn't immediately result in condylar modifications, a relationship between the two phenomena remains evident.

BMP2 rs1005464 is associated with mandibular condyle size variation

This study aimed to evaluate the association between single nucleotide polymorphisms (SNPs) in endochondral development-related genes and mandibular condyle shape, size, volume, and symmetry traits. Cone-beam Computed Tomographies and genomic DNA from 118 individuals were evaluated (age range: 15-66 years). Data from twelve 3D landmarks on mandibular condyles were submitted to morphometric analyses including Procrustes fit, principal component analysis, and estimation of centroid sizes and fluctuating asymmetry scores. Condylar volumes were additionally measured. Seven SNPs across BMP2, BMP4, RUNX2 and SMAD6 were genotyped. Linear models were fit to evaluate the effect of the SNPs on the mandibular condyles' quantitative traits. Only the association between BMP2 rs1005464 and centroid size remained significant after adjusting to account for the false discovery rate due to multiple testing. Individuals carrying at least one A allele for this SNP showed larger condylar size than common homozygotes GG (β = 0.043; 95% CI: 0.014-0.071; P value = 0.028). The model including BMP2 rs1005464, age and sex of the participants explained 17% of the variation in condylar size. Shape, volume, and symmetry were not associated with the evaluated SNPs. These results suggest that BMP2 rs1005464 might be associated with variation in the mandibular condyles size.

Orthognathic surgery effects on temporomandibular joint compressive stresses

INTRODUCTION

This study tested orthognathic surgery effects on temporomandibular joint (TMJ) compressive stresses.

METHODS

Pre- (T1) and post-surgery (T2) cone-beam computed tomography images were collected from consenting subjects aged ≥15 years. Anatomical data were used to measure surgical changes in anteroposterior mandibular position and occlusal plane angle (FH-OP), estimate condylar loading areas (mm2 ) and calculate T1 and T2 TMJ and jaw muscle forces (N) during canine biting via numerical modelling. Analysis of covariance tested for sex and biting angle differences in T2 - T1 TMJ compressive stresses (TMJ force/loading area, MPa). Principal component analyses identified jaw muscle forces that accounted for changes in T2 - T1 TMJ loads. Regression analyses tested the correlations between surgical changes in mandibular position, FH-OP, TMJ loads and muscle forces.

RESULTS

Of 148 cases screened, 28 females and 16 males provided complete records. Condylar loading areas were significantly smaller (P = .024) for females vs males (124 ± 5 vs 144 ± 7 mm2 ). T2 - T1 differences in TMJ compressive stresses varied by surgical change, biting angle and sex. Overall, the largest increases in TMJ compressive stresses post-surgery were for females with mandibular setbacks where FH-OP angle decreased. T2 - T1 changes in jaw muscle forces had moderate (ipsilateral, λ = 4.59; η2  = 0.071) to large (contralateral, λ = 1.49; η2  = 0.31) effects on TMJ loads.

CONCLUSIONS

T2 - T1 differences in TMJ compressive stresses during canine biting were affected by surgical changes in mandibular position and occlusal plane angle, biting angle and sex. Surgical changes altered jaw muscle forces for the same biting conditions and, thus, affected TMJ loads and compressive stresses.

Association Between Gender, Age, and Skeletal Class With Mandibular Condyle Morphology: A Retrospective Study

OBJECTIVES

This study aimed to examine the impact of demographic variables on mandibular condyle morphology, a critical factor in orthodontic treatment and maxillofacial surgery. The investigation focuses on the relationship between gender, age, and skeletal class with the morphological dimensions of the condyle, utilizing panoramic radiography as a diagnostic tool.

METHODOLOGY

A retrospective analysis was conducted on 150 panoramic radiographs from individuals stratified into six groups according to gender and skeletal class. Skeletal classes were determined using Steiner and McNamara cephalometry. The Kodak Carestream software (Rochester, NY: Carestream Health) was employed to measure condylar height, width, and morphology. Statistical evaluations included ANOVA, correlation assessments, and multivariate binary logistic regression to discern the differences and associations among the variables studied.

RESULTS

The findings revealed notable differences in condylar dimensions between genders across different skeletal classes, with males typically presenting larger condylar dimensions than females. The data also showed a moderate positive correlation between condyle height and width. Round-shaped condyles were the most common form found, with significant gender differences observed in certain skeletal classes. Additionally, logistic regression analysis identified significant associations between gender, age, and condylar width and shape.

CONCLUSIONS

The study concludes that demographic factors, such as gender and age, significantly affect mandibular condyle morphology. These factors should be carefully considered in clinical evaluations using panoramic radiography to enhance the precision of diagnoses and the effectiveness of subsequent orthodontic and maxillofacial treatments. The results provide valuable insights for healthcare professionals in regions where more advanced imaging techniques may not be readily available.

MRI of the temporomandibular joint in children with juvenile idiopathic arthritis: protocol and findings

Contrast-enhanced magnetic resonance imaging (MRI) is the technique of choice for diagnosis and monitoring of temporomandibular joint (TMJ) disorders in patients with juvenile idiopathic arthritis (JIA), as it is able to visualize both soft tissue and osteochondral changes. Approximately 40% of children with JIA develop inflammatory and chronic osteochondral changes observable on imaging, which if left untreated can lead to significant facial growth impairment, including facial asymmetry and retrognathia. MRI of the TMJ plays a paramount role in diagnosis and treatment monitoring in JIA since early signs of TMJ involvement are difficult to detect clinically and with physical examination. Findings of TMJ arthritis may be classified into acute and chronic domains. Early or acute manifestations include joint effusion, bone marrow edema, synovial thickening, and increased joint enhancement. With disease progression, there are characteristic osteochondral changes, including deformity of the mandibular condyle with shortening of the mandibular ramus, bone erosions, and disk abnormalities. In this pictorial essay, we describe a consensus MRI protocol for the study of the TMJ and illustrate the degree of normal and pathological MRI findings using currently available MRI scoring systems of the TMJ developed for JIA.

Cone beam computed tomography in the assessment of TMJ deformity in children with JIA: repeatability of a novel scoring system

BACKGROUND

The temporomandibular joint (TMJ) is frequently involved in juvenile idiopathic arthritis (JIA). Diagnostic imaging is necessary to correctly diagnose and evaluate TMJ involvement, however, hitherto little has been published on the accuracy of the applied scoring systems and measurements. The present study aims to investigate the precision of 20 imaging features and five measurements based on cone beam computed tomography (CBCT).

METHODS

Imaging and clinical data from 84 participants in the Norwegian study on juvenile idiopathic arthritis, the NorJIA study, were collected. Altogether 20 imaging features and five measurements were evaluated independently by three experienced radiologists for intra- and interobserver agreement. Agreement of categorical variables was assessed by Fleiss', Cohen's simple or weighted Kappa as appropriate. Agreement of continuous variables was assessed with 95% limits of agreement as advised by Bland and Altman.

RESULTS

"Overall impression of TMJ deformity" showed almost perfect intraobserver agreement with a kappa coefficient of 0.81 (95% CI 0.69-0.92), and substantial interobserver agreement (Fleiss' kappa 0.70 (0.61-0.78)). Moreover, both "flattening" and "irregularities" of the eminence/fossa and condyle performed well, with intra- and interobserver agreements of 0.66-0.82 and 0.55-0.76, respectively. "Reduced condylar volume" and "continuity" of the fossa/eminence had moderate intra- and interobserver Kappa values, whereas continuity of the condyle had Kappa values above 0.55. Measurements of distances and angles had limits of agreement of more than 15% of the sample mean.

CONCLUSIONS

We propose a CBCT-based scoring system of nine precise imaging features suggestive of TMJ deformity in JIA. Their clinical validity must be tested.

Age-related variations in position and morphology of the temporomandibular joint in individuals with anterior openbite and crossbite: a multi-cross-sectional comparative study

BACKGROUND

This study aimed to compare the age-related positional and morphological characteristics of the temporomandibular joint (TMJ) between individuals with anterior openbite or crossbite and controls.

METHODS

This multi-cross-sectional comparative study analysed cone-beam computed tomography images of 750 participants, equally divided into the openbite, crossbite, and control groups (OBG, CBG, and CG, respectively). Each group was further divided into five subgroups (8-11 years, 12-15 years, 16-19 years, 20-24 years, and 25-30 years). Measurements of the TMJ included the position of the condyles in their respective fossae and morphology of the condyles and fossae. Data were submitted to statistical analysis. The study adhered to the STROBE Statement checklist for reporting of cross-sectional studies.

RESULTS

Condyles were positioned more posteriorly with increasing age in all groups, and the condylar position was more posterior in the OBG than in the CBG. The articular eminence inclination increased with age in all the groups. There were significant differences in the articular eminence inclination among the three major groups at the age of > 15 years, and the condylar path was flatter in the CBG than in the OBG.

CONCLUSIONS

Age-related morphological and positional characteristics of the TMJ differed considerably among OBG, CBG and CG. Contrary to CBG, OBG was found to have relatively posterior condylar position and steeper condylar path.

Pamidronate Therapy Increases Trabecular Bone Complexity of Mandibular Condyles in Individuals with Osteogenesis Imperfecta

Patients with Osteogenesis Imperfecta (OI) present extra-skeletal manifestations, including important orodental and craniofacial features as dentinogenesis imperfecta, dental agenesis, failure of maxilla growth and hypotonia of masticatory muscles. These features may compromise vital functions speech and mastication. Studies have demonstrated that cyclic pamidronate infusion, the standard therapy for patients with moderate to severe OI, influences the histomorphometric pattern of different body bones. The present study aimed to investigate the condyle trabecular bone pattern in OI patients. We used fractal dimension (FD) analysis on dental panoramic radiographic images to characterize the mandibular condyle trabecular bone in adolescents diagnosed with OI and treated with pamidronate. Imaging exam of 33 adolescents of both sexes, aged between 12 and 17 years, were analyzed and compared with 99 age- and sex-matched healthy adolescents. FD in patients was significantly lower (1.23 ± 0.15) than in healthy controls (1.29 ± 0.11; p < 0.01). Type of OI, age at treatment onset, and the duration of therapy were variables that showed a statistically significant effect on the FD results. This study demonstrated that the bone architecture of mandibular condyles may be altered in pediatric patients with moderate and severe forms of OI. Also, pamidronate treatment seems to have a positive effect on condyle trabecular bone in these patients. This is supported by our finding that FD values were positively influenced by the length of cyclic pamidronate treatment at the time of imaging, as well as by the age of the individual at treatment onset.

Growth patterns and shape development of the paediatric mandible – A 3D statistical model

Background/aim

To develop a 3D morphable model of the normal paediatric mandible to analyse shape development and growth patterns for males and females.

Methods

Computed tomography (CT) data was collected for 242 healthy children referred for CT scan between 2011 and 2018 aged between 0 and 47 months (mean, 20.6 ± 13.4 months, 59.9% male). Thresholding techniques were used to segment the mandible from the CT scans. All mandible meshes were annotated using a defined set of 52 landmarks and processed such that all meshes followed a consistent triangulation. Following this, the mandible meshes were rigidly aligned to remove translation and rotation effects, while size effects were retained. Principal component analysis (PCA) was applied to the processed meshes to construct a generative 3D morphable model. Partial least squares (PLS) regression was also applied to the processed data to extract the shape modes with which to evaluate shape differences for age and sex. Growth curves were constructed for anthropometric measurements.

Results

A 3D morphable model of the paediatric mandible was constructed and validated with good generalisation, compactness, and specificity. Growth curves of the assessed anthropometric measurements were plotted without significant differences between male and female subjects. The first principal component was dominated by size effects and is highly correlated with age at time of scan (Spearman's r = 0.94, p < 0.01). As with PCA, the first extracted PLS mode captures much of the size variation within the dataset and is highly correlated with age (Spearman's r = −0.94, p < 0.01). Little correlation was observed between extracted shape modes and sex with either PCA or PLS for this study population.

Conclusion

The presented 3D morphable model of the paediatric mandible enables an understanding of mandibular shape development and variation by age and sex. It allowed for the construction of growth curves, which contains valuable information that can be used to enhance our understanding of various disorders that affect the mandibular development. Knowledge of shape changes in the growing mandible has potential to improve diagnostic accuracy for craniofacial conditions that impact the mandibular morphology, objective evaluation, surgical planning, and patient follow-up.

•

Shape and development patterns of the paediatric mandible (0 – 4 years) were evaluated using a dataset of 242 CT scans.

•

A 3D morphable model of the paediatric mandible was constructed using principal component analysis (PCA).

•

Validation experiments demonstrated that the 3D morphable model can produce realistic novel mandible samples.

•

Partial least squares (PLS) regression was applied to the dataset to evaluate shape differences for age and sex.

•

The first shape model correlated strongly with age for PCA and PLS, though little correlation was seen between shape and sex.

A theoretical analysis of longitudinal temporomandibular joint compressive stresses and mandibular growth

OBJECTIVES

To determine if temporomandibular joint (TMJ) compressive stresses during incisor biting (1) differed between growing children over time, and (2) were correlated with Frankfort Horizontal-mandibular plane angle (FHMPA, °) and ramus length (Condylion-Gonion (Co-Go), mm).

MATERIALS AND METHODS

Three-dimensional anatomical geometries, FHMPA and Co-Go, were measured longitudinally from lateral and posteroanterior cephalographs1 of children aged 6 (T1), 12 (T2), and 18 (T3) years. Geometries were used in numerical models to estimate subject-specific TMJ eminence shape and forces for incisor bite-forces of 3, 5, and 8 Newtons at T1, T2, and T3, respectively. TMJ compressive stresses were estimated via two steps: First, TMJ force divided by age-dependent mandibular condylar dimensions, and second, modified by loading surfaces' congruency. Analysis of variance and Tukey honest significant difference post-hoc tests, plus repeated measures and mixed effects model analyses were used to evaluate differences in variables between facial groups. Regression analyses tested for correlation between age-dependent compressive stresses, FHMPA, and Co-Go.

RESULTS

Sixty-five of 842 potential subjects had T1-T3 cephalographs and were grouped by FHMPA at T3. Dolichofacial (FHMPA ≥ 27°, n = 36) compared to meso-brachyfacial (FHMPA< 27°, n = 29) subjects had significantly larger FHMPA at T1-T3, shorter Co-Go at T2 and T3 (all P < .01), and larger increases in TMJ compressive stresses with age (P < .0001). Higher compressive stresses were correlated with larger FHMPA (all R2 ≥ 0.41) and shorter Co-Go (all R2 ≥ 0.49).

CONCLUSIONS

Estimated TMJ compressive stress increases from ages 6 to 18 years were significantly larger in dolichofacial compared to meso-brachyfacial subjects and correlated to FHMPA and Co-Go.

Sex and age biological variation of the mandible in a Portuguese population- a forensic and medico-legal approaches with three-dimensional analysis

The medico-legal identification is based on a set of discriminatory characteristics between individuals in their biological, social, cultural, religious, legal and economic framework. The purpose of this study was to characterize the biological variation, regarding gender and age, in a Portuguese population. A three-dimensional (3D) analysis of 215 mandibles (7-20 years old) from the database of the Laboratory of Forensic Dentistry, Faculty of Medicine, University of Coimbra (CE-112/2019) was performed. A total of 13 cephalometric points defined 10 linear variables and 7 angular variables, on 3D reconstructions from ConeBeam Computed Tomography (CBCT) images. Intra and inter-observer errors were analyzed by Technical Measurement Error test. A descriptive statistics was performed. To verify the influence of gender and age on the variables and to determine its predictive value, ANOVA and Logistic Regression Analysis were performed. Gender and age influence most of the linear variables, however, the same is not true for angular variables. In the analysis of all variables, the model has a reasonable level of sensitivity (67.8%) according to gender. For the age prediction, with all variables, the model presented a reasonable level of sensitivity, classifying 79.4% of the individuals. The results supported, with a high level of statistical significance, an adequate recognition of individuals highlighting the identification and criminal imputability of Portuguese individuals.

MRI in the Assessment of TMJ-Arthritis in Children with JIA; Repeatability of a Newly Devised Scoring System

RATIONALE AND OBJECTIVES

The temporomandibular joint (TMJ) is commonly involved in children with juvenile idiopathic arthritis. The diagnosis and evaluation of the disease progression is dependent on medical imaging. The precision of this imaging is under debate. Several scoring systems have been proposed but transparent testing of the precision of the constituents of the scoring systems is lacking. The present study aims to test the precision of 25 imaging features based on magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Clinical data and imaging were obtained from the Norwegian juvenile idiopathic arthritis study, The NorJIA study. Twenty-five imaging features of the TMJ in MRI datasets from 86 study participants were evaluated by two experienced radiologists for inter- and intraobserver agreement. Agreement of ordinal variables was measured with Cohen´s linear or weighted Kappa as appropriate. Agreement of continuous measurements was assessed with 95% limit of agreement according to Bland-Altman.

RESULTS

In the osteochondral domain, the ordinal imaging variables "loss of condylar volume," "condylar shape," "condylar irregularities," "shape of the eminence/fossa," "disk abnormalities," and "condylar inclination" showed inter- and intraobserver agreement above Kappa 0.5. In the inflammatory domain, the ordinal imaging variables "joint fluid," "overall impression of inflammation," "synovial enhancement" and "bone marrow oedema" showed inter- and intraobserver agreement above Kappa 0.5. Continuous measurements performed poorly with wide limits of agreement.

CONCLUSION

A precise MRI-based scoring system for assessment of TMJ in JIA is proposed consisting of seven variables in the osteochondral domain and four variables in the inflammatory domain. Further testing of the clinical validity of the variables is needed.

Morphological variations of the condylar head among children aged 4-15 years: A panoramic study

BACKGROUND

Growth and development of dentocraniofacial complex occurs during various stage of development of dentition with TMJ as one of its centres of growth. The condition of temporomandibular joint can be visible from its condylar head form; therefore, it is crucial to recognize the normal morphology of condylar head during different stages of development of dentition.

AIMS

The aim of the study is to view the morphological appearance of condylar head during primary dentition, mixed dentition and permenant dentition.

SUBJECT AND METHODS

400 panoramic images of 194 boys and 296 girls were collected and were divided into three groups bases on the stage of dentition. Shape of the condylar head were determined by tracing the print out of the panoramic image on an X ray viewer.

RESULTS

The study showed that during primary dentition stage shape of the conylar head was dominated by round shape and as growth and development occurs the condylar head shape changes to convex.

CONCLUSION

The study describes the normal morphology of mandibular condyles in a child population attending The dentition status as well as growth of craniofacial has a significant role in determining condylar morphology.

A three-dimensional statistical shape model of the growing mandible

Mandibular growth and morphology are important topics in the field of oral and maxillofacial surgery. For diagnostic and planning purposes, a normative database or statistical shape model of the growing mandible can be of great benefit. A collection of 874 cadaveric children's mandibles with dental age between 1 and 12 years old were digitized using computed tomography scanning and reconstructed to three-dimensional models. Point correspondence was achieved using iterative closest point and coherent point drift algorithms. Principal component analysis (PCA) was applied to find the main modes of variation in the data set. The average mandible was presented, along with the first ten PCA modes. The first mode explained 78% of the total variance; combining the first ten modes accumulated to 95% of the total variance. The first mode was strongly correlated with age and hence, with natural growth. This is the largest study on three-dimensional mandibular shape and development conducted thus far. The main limitation is that the samples lack information such as gender and cause of death. Clinical application of the model first requires validation with contemporary samples.

Spatial Analysis of the Temporomandibular Joint and Condyle Following Mandibular Distraction in Robin Sequence

ABSTRACT

To comprehensively assess changes in temporomandibular joint and mandibular condyle morphology in Robin sequence (RS) patients undergoing mandibular distraction osteogenesis (MDO). A retrospective analysis of pediatric patients with RS and functional temporomandibular joints who underwent MDO by a single surgeon was performed. Preoperative and postoperative computed tomography (CT) scans were morphometrically analyzed three-dimensional in 3-matic and Mimics (Materialise). Comparative analysis was performed using Wilcoxon signed-rank tests. Fourteen RS patients were included (28 condyles, 56 CT scans), 78% male and 22% females. The mean age at surgery was 9.4 weeks (range 1.6-46.7 weeks). The average age at initial CT was 5.3 days (range 0-11 days). The mean time interval for CT scan before MDO and after hardware removal were 8.8 ± 6.4 days and 11.2 ± 25.8 days, respectively. Rotatory changes of the condyle revealed a significantly decreased horizontal angle following MDO (-7.55°, 95% confidence interval -11.13° to -3.41°; P < 0.001). Anteroposteriorly, the angle between condylar process and ramus (incline) increased significantly (14.14°, 95% confidence interval 10.71°-19.59°; P < 0.001). Intragroup analysis revealed no difference between left versus right condylar position measurements. The condyle itself increased in size and length and the intercondylion distance increased post-MDO. There were no complications and all patients achieved relief of airway obstruction without tracheostomy. Morphologic and positional changes of the mandibular condyle following MDO in RS patients parallel changes that occur during normal development in non-RS patients. As a result, MDO may facilitate normal condylar morphology and function in RS patients.

Mandibular movements in children with deciduous and mixed dentition and in young adults with permanent dentition-the association between movements and occlusal traits

BACKGROUND

Cross-sectional studies of mandibular movements provide data on developmental trends of dentition and support planning of public health services.

OBJECTIVE

The aim of this study was to measure mandibular movement capacities in children with deciduous and mixed dentition and in young adults with permanent dentition. The influence of age and gender on mandibular movements and the association between mandibular movements and occlusal traits were analysed.

METHOD

The sample consisted of 1172 Estonians: group 1: children with deciduous dentition; group 2: children with mixed dentition; and group 3: young adults with permanent dentition. Maximum opening, mandibular laterotrusion, and protrusion were registered.

RESULTS

Age was correlated with mandibular movements. Young adults had statistically significantly larger mandibular movements as compared to children with deciduous and mixed dentition, and children with mixed dentition had larger mandibular movements as compared to children with deciduous dentition. Young adult males had larger mandibular movements than females of the same age. Associations were found between mandibular movement capacities and some occlusal traits. Mandibular movement capacities were smaller in children with crossbite and open bite as compared with children without corresponding occlusal traits. Mandibular movement capacities were larger in children with deep bite and increased overjet as compared with those without corresponding occlusal traits.

CONCLUSION

Mandibular movement capacities are age and gender dependent. Maximum mouth opening, mandibular laterotrusion, and protrusion are related, and mandibular movement and some occlusal traits are associated.

The Short-Term Effect of Active Skeletonized Sutural Distractor Appliance on Temporomandibular Joint Morphology of Class III Malocclusion Subjects

Objectives  The purpose of this study was to evaluate the short-term effect of active skeletonized sutural distractor (ASSD) appliance on temporomandibular joint morphology of class III malocclusion subjects.

Materials and Methods  This was a prospective interventional study. Cone-beam computerized tomography (CBCT) images of 22 patients were taken before and after treatment by using Planmeca Promax 3D CBCT machine version 2.9.2 (Planmeca OY Helsinki, Finland). The condylar width, height, length, roof of glenoid fossa thickness, and all joint spaces were measured. The condylar position was determined based on Pullinger and Hollander formula. The condylar shape was determined as per Kinzinger et al. The condylar volume was calculated by using Mimics software (Materialize, Belgium).

Statistical Analysis  Data analysis was performed by using SPSS software version 24. Wilcoxon paired signed-rank test was used to compare the difference in temporomandibular joint morphology and condylar volume between pre- and post-treatment measurements. Chi-square test was used to compare the condylar position and shape.

Results  The superior ( p = 0.000 on the right side, p = 0.005 on the left side) and posterior joint spaces ( p = 0.000 on both sides) were decreased after the treatment, respectively. The condyles were rotated upward and backward, thereby increasing the anterior joint spaces ( p = 0.000 on both sides) after the treatment. The condylar volume increases after treatment, but no significant differences were observed ( p = 0.903 on the right side, p = 0.062 on the left side).

Conclusion  The significant changes were observed in joint spaces. The condyles were more anteriorly placed before treatment. Condylar position and shape alter in response to ASSD treatment. The condylar volume did not show any significant change.

Content and construct validity of the Diagnostic Criteria for Temporomandibular Disorders Axis I for children

OBJECTIVE

To perform the content and construct validation of the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) Axis I, for children 7-11 years old.

MATERIALS AND METHODS

A Delphi process was used to perform the content validity of the DC/TMD Axis I. One hundred eighty-nine 7- to 11-year-old children were assessed with the adapted instrument. Confirmatory factor analysis (CFA) was used to investigate construct validity of the DC/TMD for children. A baseline one-factor model was compared against a two-factor (Model 2) and a seven-factor (Model 3) models based on the original DC/TMD. Root mean squared error of approximation (RMSEA), comparative fit index (CFI), chi-square, change in chi-square and Cronbach's α were used to analyse the data. All analyses were performed in STATA^© version 13.0.

RESULTS

Items of the DC/TMD were reduced, "history time" was changed to 2 weeks, pain intensity was assessed through a face scale, and language was adapted to be better understood by children. The amount of muscle pressure was maintained as in the original DC/TMD Axis I. The CFA led to a two- and a seven-factor model, with good fit. The internal consistency of Model 2 was .91 and of Model 3, .94.

CONCLUSION

The results of this study provide evidence to support a seven-factor representation of the DC/TMD Axis I for 7- to 11-year-old children, as well as a two-factor structure. Such findings will begin to provide researchers with confidence in the properties of this instrument when considering its inclusion in clinical research.

Stress shielding FE analysis on the temporomandibular joint

Aims

The purpose of this study is to develop a FE model of the temporomandibular joint (TMJ) to investigate a musculoskeletal System of forces able to taking into account the effect of all the muscles on the TMJ in terms of stress evaluated on the bone.

Methods

A 3-dimensional finite element model of the mandible was constructed from the images generated by cone-beam computed tomography of a patient undergoing fixed orthodontic treatment. In order to define the loading force system an exustive study was developed to investigated the entity of the Lateral pterygoid, Masseter, medial pterygoid, Temporalis, and Geniohoid digastric, muscles.

Results

Stresses in the TMJ components (disc, mandible condyle and the fossa eminence on the skull) were obtained. The results have shown stress distribution during normal occlusion.

Conclusion

An appreciation of the anatomical and mechanical features associated with the TMJ can serve as a foundation for understanding a patient's clinical presentation. Performance of a thorough patient history and clinical examination can guide the clinician toward an improved diagnostic process.

Occlusal traits of 4-5-year-old Estonians. Parents' perception of orthodontic treatment need and satisfaction with dental appearance

This study aims to evaluate the prevalence of occlusal traits and to assess parents'/caregivers' satisfaction with child's dental appearance and perception of orthodontic treatment need in 4-5-year-old Estonians. Clinical records and plaster casts of 390 children (190 girls and 200 boys, mean age 4.7 years, range 4 - 5 years) were analyzed. Assessed occlusal traits included deciduous canine and second molar sagittal relationship, overjet, overbite, crowding, midline diastema, crossbite, and scissor bite. Parents'/caregivers' opinions regarding their child's teeth were determined with a questionnaire. The most prevalent occlusal traits were symmetrical sagittal relationship in deciduous canines (78.2%) and molars (75.1%), Class I sagittal relationship in deciduous canines (69.7%) and midline diastema (67.7%). Asymmetrical sagittal canine relationship was registered in 21.8% deciduous canines and in 24.9% second deciduous molars. Parents'/caregivers' perceived orthodontic treatment need was related to Class III sagittal relationship in canines, increased overjet and overbite, negative overbite, and crossbite. Prevalence of most occlusal traits in Estonian children were in line with those reported in neighboring countries. Parents/caregivers were well able to observe occlusal traits that deviated from acceptable occlusion.

Ultrasound detected changes in joint cartilage thickness in juvenile idiopathic arthritis

AIM

The purpose of this study was to investigate the changes in joint cartilage thickness in different subtypes of juvenile idiopathic arthritis (JIA) using ultrasound, comparing them with healthy children and to evaluate the relationship with disease duration and inflammatory markers.

METHODS

We conducted a cross-sectional study comprising of 27 cases of JIA and 54 age- and sex-matched healthy children. Bilateral wrist, knee and ankle joint cartilage thicknesses were measured by ultrasound as per European League Against Rheumatism standard guidelines and compared them between JIA subtypes as well as between cases and control.

RESULTS

Descriptive analysis of the whole cohort revealed the mean age of the study population was 8.3 ± 3.2 years with mean cartilage thicknesses at the wrist, knee and ankle being 1.40 ± 0.89 mm, 1.57 ± 0.78 mm and 1.41 ± 0.85 mm, respectively. The median cartilage thicknesses of wrist, knee and ankle joints of JIA cases (n = 27) and healthy controls (n = 54) were 1.01, 1.35, 1.05 and 1.95, 2.00, 1.95, respectively. The joint cartilage thickness was significantly reduced in JIA in comparison to the healthy cohort (P < 0.01). Diseased boys suffered greater cartilage damage in knee joints compared to girls; the polyarticular variety of cases had thinner knee cartilage in comparison to the oligoarticular subtype. Further, it was found that joint cartilage destruction is independent of inflammatory markers and disease duration.

CONCLUSION

Significant cartilage thinning in addition was found in JIA children, particularly in the polyarticular subtype, and more in boys than girls, which is independent of disease duration and inflammatory markers, using ultrasound as a primary investigative tool.

Temporomandibular Joint Condyle-Disc Morphometric Sexual Dimorphisms Independent of Skull Scaling

PURPOSE

Approximately 2 to 4% of the US population have been estimated to seek treatment for temporomandibular symptoms, predominately women. The study purpose was to determine whether sex-specific differences in temporomandibular morphometry result from scaling with sex differences in skull size and shape or intrinsic sex-specific differences.

MATERIALS AND METHODS

A total of 22 (11 male [aged 74.5 ± 9.1 years]; 11 female [aged 73.6 ± 12.8 years]) human cadaveric heads with no history of temporomandibular disc derangement underwent cone beam computed tomography and high-resolution magnetic resonance imaging scanning to determine 3-dimensional cephalometric parameters and temporomandibular morphometric outcomes. Regression models between morphometric outcomes and cephalometric parameters were developed, and intrinsic sex-specific differences in temporomandibular morphometry normalized by cephalometric parameters were determined. Subject-specific finite element (FE) models of the extreme male and extreme female conditions were developed to predict variations in articular disc stress-strain under the same joint loading.

RESULTS

In some cases, sex differences in temporomandibular morphometric parameters could be explained by linear scaling with skull size and shape; however, scaling alone could not fully account for some differences between sexes, indicating intrinsic sex-specific differences. The intrinsic sex-specific differences in temporomandibular morphometry included an increased condylar medial length and mediolateral disc lengths in men and a longer anteroposterior disc length in women. Considering the extreme male and female temporomandibular morphometry observed in the present study, subject-specific FE models resulted in sex differences, with the extreme male joint having a broadly distributed stress field and peak stress of 5.28 MPa. The extreme female joint had a concentrated stress field and peak stress of 7.37 MPa.

CONCLUSIONS

Intrinsic sex-specific differences independent of scaling with donor skull size were identified in temporomandibular morphometry. Understanding intrinsic sex-specific morphometric differences is critical to determining the temporomandibular biomechanics given the effect of anatomy on joint contact mechanics and stress-strain distributions and requires further study as one potential factor for the increased predisposition of women to temporomandibular disc derangement.

Temporomandibular joint magnetic resonance imaging findings in adolescents with anterior disk displacement compared to those with juvenile idiopathic arthritis

BACKGROUND

Deformation of the mandibular condyle can be associated with anterior disk displacement (ADD) or involvement of the temporomandibular joint (TMJ) by juvenile idiopathic arthritis (JIA). Diagnostic differentiation is critical for proper management.

OBJECTIVES

To compare morphology and inflammation between TMJs with ADD and JIA.

METHODS

Retrospective assessment of contrast-enhanced TMJ MRI in 18 adolescents (15 female, mean age 15.1 ± 1.9 years) with ADD and age- and gender-matched patients with JIA. Articular disk findings, inflammatory signs and osseous morphology were compared.

RESULTS

In the ADD group, 31 of 36 disks were displaced. In total, 28 of 31 displaced disks showed thickening of the bilaminar zone. In JIA patients, the disks were mainly flattened (19/36), centrally perforated (12/36) and/or anteriorly displaced (2/36). In total, 19 of 31 TMJs with ADD showed various degrees of inflammation, with joint effusion, synovial thickening and joint enhancement not significantly different from JIA patients. Osseous deformity was present in 27 of 31 TMJs with ADD, with frequent erosions in both groups (ADD 25/31; JIA 32/36, P = 0.55) but lower grades of condylar and temporal bone flattening than in JIA (P ≤ 0.001). Glenoid fossa depth was preserved in 28 of 31 joints with ADD and decreased in 26 of 36 joints with JIA (P < 0.0001). Mandibular ramus height was decreased in both groups.

CONCLUSION

In adolescents, inflammatory signs are common MRI findings in symptomatic TMJs with ADD and thus should not be considered diagnostic for JIA involvement. In this cohort, both entities had high rates of condylar deformity, while TMJs with ADD showed a better-preserved and often normal shape of the glenoid fossa.

Developing a reference MRI database for temporomandibular joints in healthy children and adolescents

BACKGROUND

Recognition of normal temporomandibular joints (TMJs) is essential to assess arthropathic changes. Few, if any, prior studies have evaluated the morphological appearance of growing TMJs by magnetic resonance (MR) examinations in the pediatric population.

OBJECTIVE

This study aimed to determine normative osseous appearance of growing TMJs according to age and gender, both qualitatively and quantitatively, concerning structural and bone marrow changes.

MATERIALS AND METHODS

From 1,036 MR scans screened, one joint was included from each of 157 patients (76% female; 2-18 years) presenting with at least one normal-appearing TMJ was included. Quantitatively, mandibular condyle was characterized by measuring the following: (i) head-neck angle, (ii) anteversion angle, (iii) condylar dimensions (mediolateral, craniocaudal and anteroposterior [AP]) and (iv) condylar volume. Furthermore, qualitative categorization of condylar shape, into one of three types, and condylar bone marrow type was performed.

RESULTS

The head-neck angle significantly correlated with age (bivariable regression β =0.60, P<0.001), indicating an increase of 1.6 degrees per year. Except for AP diameter of condyles, all other mandibular dimensions and condylar volume increased with age (β =0.20-0.59, P≤0.001-0.004). Significant age difference was observed among the different condylar shapes (P<0.001), indicating a change from rounded head without anterior tilt to rectangular head with anterior tilt. Lastly, mandibular condylar size, measured by volume and by AP and mediolateral dimensions, appeared larger in males.

CONCLUSION

The morphology of the mandibular condyles changes with age. During development, the shape of the condyles changes from round to rectangular in contour with the development of the anterior condylar tilt, as measured by the head-neck angle.

Mechanobehavior and Ontogenesis of the Temporomandibular Joint

Craniofacial secondary cartilages of the mandibular condyle and temporomandibular joint (TMJ) eminence grow in response to the local mechanical environment. The intervening TMJ disc distributes normal loads over the cartilage surfaces and provides lubrication. A better understanding of the mechanical environment and its effects on growth, development, and degeneration of the TMJ may improve treatments aimed at modifying jaw growth and preventing or reversing degenerative joint disease (DJD). This review highlights data recorded in human subjects and from computer modeling that elucidate the role of mechanics in TMJ ontogeny. Presented data provide an approximation of the age-related changes in jaw-loading behaviors and TMJ contact mechanics. The cells of the mandibular condyle, eminence, and disc respond to the mechanical environment associated with behaviors and ultimately determine the TMJ components' mature morphologies and susceptibility to precocious development of DJD compared to postcranial joints. The TMJ disc may be especially prone to degenerative change due to its avascularity and steep oxygen and glucose gradients consequent to high cell density and rate of nutrient consumption, as well as low solute diffusivities. The combined effects of strain-related hypoxia and limited glucose concentrations dramatically affect synthesis of the extracellular matrix (ECM), which limit repair capabilities. Magnitude and frequency of jaw loading influence this localized in situ environment, including stem and fibrocartilage cell chemistry, as well as the rate of ECM mechanical fatigue. Key in vivo measurements to characterize the mechanical environment include the concentration of work input to articulating tissues, known as energy density, and the percentage of time that muscles are used to load the jaws out of a total recording time, known as duty factor. Combining these measurements into a mechanobehavioral score and linking these to results of computer models of strain-regulated biochemical events may elucidate the mechanisms responsible for growth, maintenance, and deterioration of TMJ tissues.

Effect of Measurement Technique on TMJ Mandibular Condyle and Articular Disc Morphometry: CBCT, MRI, and Physical Measurements

PURPOSE

Accurate description of the temporomandibular size and shape (morphometry) is critical for clinical diagnosis and surgical planning and the design and development of regenerative scaffolds and prosthetic devices and to model the temporomandibular loading environment. The study objective was to determine the 3-dimensional morphometry of the temporomandibular joint (TMJ) condyle and articular disc using cone-beam computed tomography (CBCT), magnetic resonance imaging (MRI), and physical measurements of the same joints using a repeated measures design and to determine the effect of the measurement technique on temporomandibular size and shape.

MATERIALS AND METHODS

Human cadaveric heads underwent a multistep protocol to acquire physiologically meaningful measurements of the condyle and disc. The heads first underwent CBCT scanning, and solid models were automatically generated. The superficial soft tissues were dissected, and intact TMJs were excised and underwent MRI scanning, with solid models generated after manual segmentation. After MRI, the intact joints were dissected, and physical measurements of the condyle and articular disc were performed. The CBCT-based model measurements, MRI-based model measurements, and physical measurements were standardized, and a repeated measures study design was used to determine the effect of the measurement technique on the morphometric parameters.

RESULTS

Multivariate general linear mixed effects models showed significant effects for measurement technique for condylar morphometric outcomes (P < .001) and articular disc morphometric outcomes (P < .001). The physical measurements after dissection were larger than either the CBCT-based or MRI-based measurements. Differences in imaging-based morphometric parameters followed a complex relationship between imaging modality resolution and contrast between tissue types.

CONCLUSIONS

Physical measurements after dissection are still considered the reference standard. However, owing to their inaccessibility in vivo, understanding how the imaging technique affects the temporomandibular size and shape is critical toward the development of high-fidelity solid models to be used in the design and development of regenerative scaffolds, surgical planning, prosthetic devices, and anatomic investigations.

Imaging of temporomandibular joint abnormalities in juvenile idiopathic arthritis with a focus on developing a magnetic resonance imaging protocol

Inflammation and damage in the temporomandibular joint (TMJ) often develop without clinical symptoms but can lead to severe facial growth abnormalities and impaired health-related quality of life, making early diagnosis of TMJ changes crucial to identify. Inflammatory and osteochondral changes detectable through magnetic resonance imaging (MRI) occur in TMJs of approximately 40% of children with juvenile idiopathic arthritis (JIA), and no other imaging modality or physical method of examination can reliably detect these changes. Therefore contrast-enhanced MRI is the diagnostic standard for diagnosis and interval monitoring of JIA. However the specific usage of MRI for TMJ arthritis is not standardized at present. There is a recognized need for a consensus effort toward standardization of an imaging protocol with required and optional sequences to improve detection of pathological changes and shorten study time. Such a consensus imaging protocol is important for providing maximum information with minimally necessary sequences in a way that allows inter-site comparison of results of clinical trials and improved clinical management. In this paper we describe the challenges of TMJ imaging and present expert-panel consensus suggestions for a standardized TMJ MRI protocol.

Normal magnetic resonance appearances of the temporomandibular joints in children and young adults aged 2-18 years

BACKGROUND

Knowledge of normal appearances of the temporomandibular joint (TMJ) is paramount when assessing the joint for disease in juvenile idiopathic arthritis. Reliable features defining normal TMJs in children are limited.

OBJECTIVE

To establish reliable normal standards for the TMJ at magnetic resonance imaging (MRI).

MATERIALS AND METHODS

We included children and young adults aged 2-18 years undergoing a head MRI for reasons not believed to affect the TMJs. We assessed TMJ anatomy and contrast enhancement using a high-resolution 3-D T1-weighted sequence. We noted joint fluid and bone marrow oedema based on a T2-weighted sequence. Three experienced radiologists read all examinations twice in consensus and defined intraobserver consensus agreement.

RESULTS

We evaluated the TMJs in 101 children and young adults (45 female), mean age 10.7 years (range 2-18 years). The intraobserver consensus agreement for the assessment of anterior condylar inclination in the sagittal/oblique plane was moderate to good (Cohen κ=0.7 for the right side). Cohen κ for intraobserver consensus agreement for condylar shape in the coronal plane on a 0-2 scale was 0.4 for the right and 0.6 for the left. Intraobserver agreement for measurement of joint space height and assessment of bone marrow oedema was poor. There was a statistically significant increase in anterior inclination by age in the sagittal plane on a 0-2 scale (P<0.0001). Eighty percent of the condyles showed a rounded shape in the coronal plane while 20% showed mild flattening. Thirty-five of 36 right TMJs showed contrast enhancement (mild enhancement in 32 joints, moderate in 3 joints).

CONCLUSION

Subjective assessment of the anterior condylar inclination in the sagittal/oblique plane and condylar flattening in the coronal plane can be considered precise features for describing TMJ anatomy in healthy children. There is an increasing anterior inclination by age. Mild contrast enhancement of the TMJs should be considered a normal finding.

Temporomandibular joint atlas for detection and grading of juvenile idiopathic arthritis involvement by magnetic resonance imaging

Contrast-enhanced magnetic resonance imaging (MRI) is considered the diagnostic standard for identifying involvement of the temporomandibular joint by juvenile idiopathic arthritis. Early or active arthritis is shown as bone marrow oedema, joint effusion, synovial thickening and increased joint enhancement. Subsequent joint damage includes characteristic deformity of the mandibular condyle, bone erosion, disk abnormalities and short mandibular ramus due to impaired growth. In this pictorial essay, we illustrate normal MRI findings and growth-related changes of the temporomandibular joint in children. The rationale and practical application of semiquantitative MRI assessment of joint inflammation and damage are discussed and presented. This atlas can serve as a reference for grading temporomandibular joint arthritis according to the scoring systems proposed by working groups of OMERACT (Outcome Measures in Rheumatology and Clinical Trials) and the EuroTMjoint research network. Systematic assessment of the level of inflammation, degree of osteochondral deformation, and growth of the mandibular ramus by MRI may aid in monitoring the course of temporomandibular joint arthritis and evaluating treatment options.

Tooth loss and craniofacial factors associated with changes in mandibular condylar morphology

Objective: To investigate the association between tooth loss and craniofacial factors with changes in mandibular condylar morphology. Methods: A total of 123 patients participated in this cross-sectional study. The mandibular condylar morphology was evaluated using digital panoramic radiography. The exposure variables included gender, age group, molar relationship, facial growth pattern, facial asymmetry, dental midline, posterior crossbite, presence of fixed dental prosthesis, and tooth loss. Results: Unilateral and bilateral mandibular condyle structural alterations were found in 20.3% and 28.5% of the sample, respectively. After the adjustment analysis, posterior crossbite (adjusted OR = 3.34, 95% CI = 1.23-9.06) and tooth loss (adjusted OR = 4.08, 95% CI = 1.72-9.64) were associated with the outcome. The tooth type associated with mandibular condyle structural alterations were premolars and upper molars. Conclusion: The findings suggest that posterior crossbite and tooth loss are associated with mandibular condyle structural alterations.

Disk abnormality coexists with any degree of synovial and osseous abnormality in the temporomandibular joints of children with juvenile idiopathic arthritis

BACKGROUND

MRI manifestation of temporomandibular joint arthritis is frequently reported in children with juvenile idiopathic arthritis. However, little attention has been paid to temporomandibular joint disk abnormalities.

OBJECTIVE

To assess combinations of MRI findings in the symptomatic temporomandibular joint in children with juvenile idiopathic arthritis with focus on disk abnormalities.

MATERIALS AND METHODS

This was a retrospective study of 46 patients with juvenile idiopathic arthritis, mean age 12 years (range: 5-17 years). Mean disease duration was 70 months (standard deviation: 61 months). MR images of 92 temporomandibular joints were scored for thickness of abnormally enhancing synovium (synovitis), joint effusion, bone marrow oedema, abnormal bone shape, bone erosion and disk abnormalities.

RESULTS

The 92 temporomandibular joints were categorized as A: No synovitis and normal bone shape (30/92; 33%), B: Synovitis and normal bone shape (14/92: 15%), C: Synovitis and abnormal bone shape (38/92; 41%) and D: No synovitis but abnormal bone shape (10/92; 11%). Thirty-six of the 46 patients (78%) had synovitis and 33/46 (72%) had abnormal bone shape, most frequently in combination (30/46; 65%). Disk abnormalities (flat disk, fragmented disk, adherent disk and displaced disk) were found in 29/46 patients (63%). Disk abnormalities were found in all categories of juvenile idiopathic arthritis involved temporomandibular joints (B: 8/14 [57%]; C: 25/38 [66%] and D: 7/10 [70%]). Disk displacement was found in half of the joints (7/14) in category B. Synovitis was most pronounced in this category.

CONCLUSION

Disk abnormalities were frequent. Disk displacement also occurred in joints with early temporomandibular joint arthritis, i.e., with normal bone shape. Other disk abnormalities were found in joints with bone abnormalities. Attention should be paid to disk abnormalities both in early and long-standing temporomandibular joint arthritis in children with juvenile idiopathic arthritis.

Juvenile idiopathic arthritis and the temporomandibular joint: A comprehensive review

Juvenile idiopathic arthritis is the most common inflammatory rheumatic disease of childhood and represents a series of chronic inflammatory arthritides of unknown cause. Involvement of the temporomandibular joint has been reported in up to 87% of children with juvenile idiopathic arthritis when based on magnetic tomography imaging; it can be asymptomatic and may lead to severe long term complications. In this review a summary of the contemporary literature of imaging of the temporomandibular joint in children with juvenile idiopathic arthritis will be provided, including ultrasound which is a valuable method for guided joint injections, but does not necessarily allow detection of acute inflammation, cone beam computed tomography, which has emerged as a feasible and accurate low-dose alternative as compared to conventional computed tomography to detect destructive change, and magnetic resonance imaging which is considered the method of choice for assessing acute, inflammatory change, although the lack of normative standards remains a challenge in children.

Is early TMJ involvement in children with juvenile idiopathic arthritis clinically detectable? Clinical examination of the TMJ in comparison with contrast enhanced MRI in patients with juvenile idiopathic arthritis

BACKGROUND

To test clinical findings associated with early temporomandibular joint (TMJ) arthritis in comparison to the current gold standard contrast enhanced magnetic resonance imaging (MRI) in children with juvenile idiopathic arthritis (JIA).

METHODS

Seventy-six consecutive JIA patients were included in this study. Rheumatological and orthodontic examinations were performed blinded to MRI findings. Joint effusion and/or increased contrast enhancement of synovium or bone as well as TMJ deformity were assessed on MRI and compared to clinical findings. The maximal mouth opening capacity (MOC) of the JIA patients was compared to normative values obtained from a cohort of 20719 school children from Zürich, Switzerland.

RESULTS

On MRI a total of 54/76 (71%) patients and 92/152 (61%) joints had signs of TMJ involvement. MRI showed enhancement in 85/152 (56%) and deformity in 39/152 (26%) joints. MOC, asymmetry and restriction in condylar translation showed significant correlation to TMJ enhancement and deformity, whereas antegonial notching was correlated with TMJ deformity only. When joints with deformity were excluded, enhancement alone did not show a significant correlation with any clinical factor.

CONCLUSIONS

Clinical findings in affected TMJs are correlated with structural damage only. Therefore clinical assessment of TMJs does not allow to diagnose early arthritis accurately and will still depend on contrast enhanced MRI.

Contrast-enhanced MRI of the temporomandibular joint: findings in children without juvenile idiopathic arthritis

BACKGROUND

Contrast-enhanced magnetic resonance imaging (MRI) is highly sensitive for assessing temporomandibular joint (TMJ) involvement in juvenile idiopathic arthritis (JIA), but only sparse data exist on normal TMJ appearance in children.

PURPOSE

To determine normal MRI appearance and enhancement pattern of pediatric TMJ as basis for diagnosing early arthritis.

MATERIAL AND METHODS

In 27 children (age range, 1.2-16.8 years) without TMJ pathology undergoing head MRI, fat-saturated T2-weighted (T2W) and postcontrast fat-saturated T1-weighted (T1W) images sagittally aligned to the 54 TMJs, besides standard T1W and T2W images, were assessed for bony and soft tissue signal intensity (SI), the amount of perceptible joint fluid, and contrast enhancement (CE).

RESULTS

Bone marrow SI and CE of the mandible were consistent with varying degrees of residual red marrow in 96% of joints. The mandibular condyles were mostly isointense to the ramus, but in 9% showed mild edema-like bone marrow SI and CE. Small amounts of intraarticular fluid were detected in 31% on T2W images without fat saturation and in 83% on T2W images with fat saturation as fine lines in the upper or lower joint compartment or as small dots in an articular recess. Seventy-nine percent of all TMJs showed intense joint enhancement on early images restricted to areas of intraarticular fluid.

CONCLUSION

Small amounts of joint fluid with intense CE are a common MRI finding in TMJs of children without JIA and therefore should not be considered diagnostic for early arthritis.

The joints in juvenile idiopathic arthritis

Abstract

Juvenile idiopathic arthritis is the most common rheumatic entity in childhood. Imaging has become an important supplement to the clinical assessment of children with JIA. Radiographs still play an important role in the workup, and long-term follow-up in children with JIA, but are not sensitive to findings in the early disease stage. Both ultrasound and MRI are more sensitive to inflammatory changes than clinical assessment alone. However, the differentiation between normal findings and pathology can be challenging, particularly in early disease. The objective of this review is to discuss the role of imaging in JIA, describe the typical findings on different modalities and highlight the challenges we face regarding the reliability and accuracy of the different methods for imaging the joints in children with JIA.

Key Points

• Imaging is an important supplement to the clinical examination in JIA.

• Ultrasound is more sensitive for detecting synovitis than clinical examination alone.

• MRI can depict all relevant structures in joint inflammation.

• The differentiation between normal variants and pathology is difficult in children.

Early detection of temporomandibular joint arthritis in children with juvenile idiopathic arthritis - the role of contrast-enhanced MRI

BACKGROUND

Early treatment of temporomandibular joint (TMJ) arthritis is crucial in children with juvenile idiopathic arthritis (JIA) to prevent permanent functional impairment. As involvement of TMJs is often asymptomatic, contrast-enhanced MRI is regarded as the most sensitive noninvasive diagnostic tool.

OBJECTIVE

To evaluate the degree of contrast enhancement in TMJs of children and adolescents with JIA in comparison to normal controls from a previous study.

MATERIALS AND METHODS

Dynamic contrast-enhanced MRI of 50 children and adolescents with JIA (6.3 to 18 years of age; mean: 12 years) were retrospectively analysed. We assessed morphological abnormalities and postcontrast time-intensity curves of the soft joint tissue and the mandibular condyle. Ratios were calculated to quantify postcontrast signal intensities (SI) in relation to precontrast SI at initial (1 min postcontrast) and maximum (6 min postcontrast) increase.

RESULTS

Time-intensity curves followed similar biphasic patterns in normal and pathological joints. In joints with morphological signs of arthritis, mean SI ratios were on average higher than in normal joints of the reference group, but ranges of values widely overlapped. Arthritis: mean initial increase of SI 62% (±2 S.D. 18-105%), mean maximum SI 106% higher than precontrast (±2 S.D. 46-166%). Normal: mean initial increase of SI 49% (±2 S.D. 14- 85%), mean maximum of SI 73% (±2 S.D. 23-123%).

CONCLUSIONS

Given this considerable overlap of results in dynamic contrast-enhanced MRI, the degree of contrast enhancement alone did not allow differentiation between TMJs with and without signs of inflammation. Thickening of the soft joint tissue seems to remain the earliest sign to reliably indicate TMJ arthritis.

Temporomandibular disorders. Part 1: anatomy and examination/diagnosis

Temporomandibular disorders (TMD) are a heterogeneous group of diagnoses affecting the temporomandibular joint (TMJ) and surrounding tissues. A variety of methods for evaluating and managing TMD have been proposed within the physical therapy profession but these sources are not peer-reviewed and lack updates from scientific literature. The dental profession has provided peer-reviewed sources that lack thoroughness with respect to the neuromusculoskeletal techniques utilized by physical therapists. The subsequent void creates the need for a thorough, research informed, and peer-reviewed source regarding TMD evaluation and management for physical therapists. This paper is the first part in a two-part series that seeks to fill the current void by providing a brief but comprehensive outline for clinicians seeking to provide services for patients with TMD. Part one focuses on anatomy and pathology, arthro- and osteokinematics, epidemiology, history taking, and physical examination as they relate to TMD. An appreciation of the anatomical and mechanical features associated with the TMJ can serve as a foundation for understanding a patient's clinical presentation. Performance of a thorough patient history and clinical examination can guide the clinician toward an improved diagnostic process.

Temporomandibular joint disorders in children

A child's difficulty in verbalizing the precise location and nature of facial pain and jaw dysfunction often results in a nondefinitive history, increasing the importance of the dentist's awareness of the early signs and symptoms of temporomandibular joint disorders (TMD). A focused examination of the masticatory musculature, the temporomandibular joints, and associated capsular and ligamentous structures can reveal if a patient's symptoms are TMD in origin. An accurate differential diagnosis enables timely referral to appropriate health care providers and minimizes the use of diagnostic imaging.

Contrast-enhanced MRI of normal temporomandibular joints in children--is there enhancement or not?

OBJECTIVES

To determine the degree of contrast enhancement of normal TM joint (TMJ) in children and to provide reference data for patients with JIA.

METHODS

A total of 100 dynamic contrast-enhanced MRI of 46 children from 1.6 to 18 years (median 9.1 years), who underwent the examinations for reasons other than TMJ disease, were retrospectively analysed in accordance with our local ethics committee. Time-intensity curves of the mandibular condyle and the soft tissue of the joint were assessed in relation to pre-contrast images and to muscle tissue.

RESULTS

After contrast injection the soft tissue of all joints showed a rapid initial increase of signal intensity (SI) followed by a slow increase, with the maximum after 6 min (end of the scan). Maximum SI in the joint tissue was on average 73% higher than pre-contrast, 53% higher than in the condyle and 20% higher than in an adjacent muscle. However, in 15% of measurements post-contrast SI of the muscle was higher than that of the joint tissue. The enhancement curve of the bone marrow in the condyle showed a peak by 2 min post-contrast.

CONCLUSION

Contrast enhancement is a normal finding in the soft tissue and the condyle of the TMJ in children and adolescents. This should be taken into account when assessing the TMJ of children with JIA. As the relative enhancement of joint in comparison with muscle tissue proved to be variable, subtraction analysis of pre- and post-contrast T1 weighted images seems to provide a better basis for visual assessment.