TMJ disorders and pain: Assessment by contrast-enhanced MRI

Detunable wireless resonator arrays for TMJ MRI: A comparative study

Temporomandibular Joint Magnetic Resonance Imaging (TMJ MRI) is crucial for diagnosing temporomandibular disorders (TMDs). This study advances the use of inductively coupled wireless coils to enhance imaging quality in TMJ MRI. After investigating multiple wireless resonator configurations, including a 1-loop design with a loop diameter of 9 cm, a 2-loop design with each loop having a diameter of 7 cm, and a 3-loop design with each loop having a diameter of 5 cm, our findings indicate that the 3-loop configuration achieves the optimal signal-to-noise ratio (SNR), surpassing other wireless arrays. Bilateral deployment of wireless coils further amplifies SNR, enabling superior visualization of TMJ structures, particularly with the 3-loop design. This cost-effective and comfortable solution, featuring a detunable design, eliminates the need for system parameter adjustments. The study indicates broad adaptability across MRI platforms, enhancing TMJ imaging for routine clinical diagnostics of TMDs.

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

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

Temporomandibular joint pathologies: pictorial review

In this pictorial review, an introductory paragraph emphasizes the significance of some anatomical aspects for optimal imaging of the temporomandibular joint (TMJ). The most frequent pathologies: internal derangement (ID) and osteoarthritis (OA) are comprehensively discussed and illustrated. Less common conditions: ID and OA-like changes in children and adolescents, idiopathic condylar resorption, inflammatory arthritis, and juvenile idiopathic arthritis are briefly discussed. A short paragraph on differential diagnostics in young patients is included followed by a brief comment on expansile lesions that occasionally may occur in the TMJ.

Reconstructed magnetic resonance image-based effusion volume assessment for temporomandibular joint arthralgia

BACKGROUND

Joint effusion is often noticed in magnetic resonance image (MRI) and its diagnostic value for arthralgia of the temporomandibular joint (TMJ) remains obscure.

OBJECTIVE

To develop a method for quantitatively evaluating the joint effusion revealed in MRI and its diagnostic value for arthralgia of the TMJ.

METHODS

Two-hundreds and twenty-eight TMJs, 101 with arthralgia (Group P) and 105 without (Group NP) from 103 patients, and 22 TMJs (Group CON) from 11 asymptomatic volunteers were examined by using MRI. The effusion volume was measured after constructing a three-dimensional structure of the joint effusion revealed in MRI by using the ITK-SNAP software. The diagnostic capabilities of the effusion volume on arthralgia were evaluated with receiver operating characteristic (ROC) curve analysis.

RESULTS

Totally 146 joints showed MRI signs of joint effusion, including nine joints from Group CON. However, the medium volume was greater in Group P (66.65 mm3 ), but was much similar in Group CON (18.33 mm3 ) to Group NP (27.12 mm3 ). The effusion volume larger than 38.20 mm3 was validated to discriminate Group P from Group NP. The AUC value was 0.801 (95% CI 0.728 to 0.874), with a sensitivity of 75% and specificity of 78.9%. The median volume of the joint effusion was larger in those with than without bone marrow oedema, osteoarthritis, Type-III disc configurations, disc displacement and higher signal intensity of the retrodiscal tissue (all, p < .05).

CONCLUSION

The present method for evaluate joint effusion volume well discriminated painful TMJs from non-pain ones.

Chemokine Regulation in Temporomandibular Joint Disease: A Comprehensive Review

Temporomandibular joint disorders (TMDs) are conditions that affect the muscles of mastication and joints that connect the mandible to the base of the skull. Although TMJ disorders are associated with symptoms, the causes are not well proven. Chemokines play an important role in the pathogenesis of TMJ disease by promoting chemotaxis inflammatory cells to destroy the joint synovium, cartilage, subchondral bone, and other structures. Therefore, enhancing our understanding of chemokines is critical for developing appropriate treatment of TMJ. In this review, we discuss chemokines including MCP-1, MIP-1α, MIP-3a, RANTES, IL-8, SDF-1, and fractalkine that are known to be involved in TMJ diseases. In addition, we present novel findings that CCL2 is involved in β-catenin-mediated TMJ osteoarthritis (OA) and potential molecular targets for the development of effective therapies. The effects of common inflammatory factors, IL-1β and TNF-α, on chemotaxis are also described. In conclusion, this review aims to provide a theoretical basis for future chemokine-targeted therapies for TMJ OA.

Imaging of the temporomandibular joint

Temporomandibular disorders are common, especially in young to middle-aged women, and most settle with supportive treatment. Imaging is indicated for the small percentage of cases that do not respond to conservative management and when the diagnosis is no doubt. The temporomandibular joint (TMJ) is a bilateral synovial articulation between the mandible and skull base. It has an intra-articular disc dividing the joint into superior and inferior compartments and the articular surfaces are lined with fibrocartilage. The normal imaging anatomy of the TMJ is described and illustrated. Different movements occur in each joint compartments: a hinge movement in the inferior joint space and translation or gliding in the superior joint space. Internal derangement is the commonest disorder affecting the TMJ and is most commonly due to disc displacement, followed by osteoarthritis and inflammatory arthritides. The imaging findings, primarily on magnetic resonance imaging (MRI) and computed tomography (CT), of internal derangement and less common disorders of the joint, are reviewed and illustrated. Optimal imaging protocols are discussed with detailed reporting guidelines.

Imaging of orofacial pain

BACKGROUND

Orofacial pain is a common complaint, with an estimated 75% of cases caused by dental disease, specifically a diseased pulp. A small percentage of orofacial pain cases will require specialist referral most commonly to oral medicine specialists or oral and maxillofacial surgeons from a dental perspective, or otolaryngologists or neurologists from a medical perspective.

IMAGING MODALITIES

Following a thorough history and clinical examination, imaging is often required to narrow the differential diagnosis or answer a specific query related to the final diagnosis. A range of imaging modalities can be used to evaluate orofacial pain including dental panoramic tomography (DPT), intraoral radiographs, cone beam computed tomography (CBCT), multidetector computed tomography (MDCT), ultrasonography (US), magnetic resonance imaging (MRI) and nuclear medicine.

IMAGING PROTOCOLS

This paper provides a guideline outlining imaging protocols for categories of facial pain divided into: (a) unilateral odontalgia; (b) unilateral facial pain; (c) combined unilateral odontalgia and facial pain; (d) trigeminal neuralgia; (e) trigeminal neuropathic pain with or without other sensory, autonomic or motor features; (f) temporomandibular joint disorders and associated pain; (g) referred pain and (h) non-specific orofacial pain.

CONCLUSION

Imaging for orofacial pain should be tailored to answer a specific query related to the aetiology of the reported pain. This should result in a specific diagnosis or narrowing of the differential diagnosis as possible causes of orofacial pain are eliminated. Choosing the correct imaging modality and protocol based on the pain category is important for efficient and effective pain diagnosis and management.

Does Incidence of Temporomandibular Disc Displacement With and Without Reduction Show Similarity According to MRI Results?

Purpose

The aim of this study is to assess MRI reports of the patients and to provide retrospective analysis by conducting detailed evaluation of temporomandibular disc position.

Patients and Methods

MRI images of 259 patients from 2008 to 2017 were reviewed retrospectively. Existence of disc displacement in joint with and without reduction, existence of effusion in joint gap, arthritis, degenerative changes in joints and limitation of movement of joint and anatomic characteristics were evaluated.

Results

One hundred and seventeen (45.2%) of the patients had healthy joint connection bilaterally. Anterior disc displacement was observed in 101 (38.9%) of the patients. The number of the patients having disc displacement with reduction was 50 (19.3%) and without reduction was 51 (19.6%) similarly.

Conclusion

The incidence of anterior disc displacement with or without reduction was similar; besides this, the majority of the patients diagnosed with anterior disc displacement were unilateral.

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.

Correlation between clinical variables and magnetic resonance imaging findings in symptomatic patients with chronic temporomandibular articular disc displacement with reduction: A retrospective analytical study

Objective: To correlate the clinical aspects of symptomatic patients with chronic articular disc displacement with reduction with alterations in the articular disc (AD) morphology and sagittal position. Methods: Records from 109 patients were selected that included data on AD morphology and sagittal position as determined by MRI. According to the MRI results, the sagittal position and AD morphology with opened and closed mouth were correlated with many clinical variables. Results: More than half of the patients studied were female, and the biconcave and hemiconvex morphologies were most common. Thirty-four patients (31.3%) presented with restricted maximum interincisal distance (MID). The biplanar morphology was associated with eccentric bruxism and MID (p < 0.05). Visual analog scale (VAS) scores between 2 and 7 were shown to be risk factors (p < 0.05). Conclusion: The mouth position can influence AD morphology and eccentric bruxism. VAS scores and unknown etiology were risk factors.

Self-reported frequency of temporomandibular disorders among undergraduate students at Taibah University

Objectives

This study aimed to evaluate the prevalence and severity of temporomandibular joint (TMJ) disorders among undergraduate students. In addition, the severity of TMD was examined in terms of its relationship with gender, age and field of study.

Methods

A total of 439 undergraduate students of both genders (age range: 20–27 years) who were studying at various colleges at Taibah University were invited to participate in this study. Each student was provided with a questionnaire, and the significance and purpose of the study were explained. The data were collected using Fonseca's questionnaire, an instrument that assessed the demographic characteristics of the students and included ten key questions. The severity of TMD was categorized as no, mild, moderate or severe. The data were analysed using SPSS Version 22 (IBM, Illinois, USA). The chi-square test was used to compare the data from different groups and to determine whether the differences were statistically significant.

Results

Of those who were invited, 78 students did not return the questionnaires, whereas another 11 were excluded due to their submitting an incomplete questionnaire. A majority of the students reported no TMD (46.7%) or mild TMD (42.7%). A moderate level of TMD was reported by 8.8% of students. Only 1.7% of students reported severe TMD. No significant differences were observed in the severity of TMD in terms of student age or field of study.

Conclusion

TMD is more prevalent among female students than male students. However, its occurrence is not affected by the age and field of study of the student.

The usefulness of diagnostic imaging for the assessment of pain symptoms in temporomandibular disorders

The causes of pain symptoms in the temporomandibular joint (TMJ) and masticatory muscle (MM) regions may not be determined by clinical examination alone. In this review, we document that pain symptoms of the TMJ and MM regions in patients with temporomandibular disorders (TMDs) are associated with computed tomography and magnetic resonance (MR) findings of internal derangement, joint effusion, osteoarthritis, and bone marrow edema. However, it is emphasized that these imaging findings must not be regarded as the unique and dominant factors in defining TMJ pain. High signal intensity and prominent enhancement of the posterior disk attachment on fat saturation T2-weighted imaging and dynamic MR imaging with contrast material are closely correlated with the severity of TMJ pain. Magnetic transfer contrast, MR spectroscopy, diffusion tensor imaging, and ultrasonography findings have helped identify intramuscular edema and contracture as one of the causes of MM pain and fatigue. Recently, changes in brain as detected by functional MR neuroimaging have been associated with changes in the TMJ and MM regions. The thalamus, the primary somatosensory cortex, the insula, and the anterior and mid-cinglate cortices are most frequently associated with TMD pain.

Is There an Association Between Temporomandibular Joint Effusion and Arthralgia?

PURPOSE

The literature on joint effusion (JE) and its association with clinical and radiologic variables in patients with temporomandibular disorders (TMDs) is inconsistent and is characterized by multiple methodologic limitations. The primary aim of this investigation was to evaluate the association between magnetic resonance imaging (MRI) identified JE and temporomandibular joint (TMJ) arthralgia. The secondary aim of this investigation was to determine the association between JE and other clinical and MRI-identified soft tissue characteristics.

MATERIALS AND METHODS

A retrospective cohort study was conducted. Clinical and soft tissue imaging assessments were carried out according to the Diagnostic Criteria for Temporomandibular Disorders guidelines. The dependent variable was JE and the primary independent variable was arthralgia. The secondary independent variables were TMJ pain-associated characteristics and MRI-identified variables. When applicable, Pearson χ² or t test was used to determine the statistical associations between JE and clinical characteristics and between JE and MRI-identified variables. Furthermore, generalized estimating equation (GEE) modeling was conducted to determine which of the independent clinical and MRI-identified variables were associated with JE.

RESULTS

Data for 158 participants, representing 312 joints, were extracted. The mean age of the female sample (59.4%) was 31 ± 11.1 years and that of the male sample (40.6%) was 29.8 ± 9.7 years. No association was found between JE and arthralgia. However, statistically significant associations were found between JE and lateral disc rotation (P = .001) and between JE and disc position in the coronal and sagittal planes (P = .001). The GEE model suggested that disc displacement with reduction (odds ratio = 2.5) was a statistically relevant contributing factor for JE in the absence of degenerative joint disease.

CONCLUSION

Results associated JE with the position of the disc in the sagittal plane. No association was found between JE and arthralgia or TMJ pain-associated clinical characteristics in patients with TMDs.

Association of bone marrow edema with temporomandibular joint (TMJ) osteoarthritis and internal derangements

PURPOSE

This study reviewed the dental literature in order to determine the association of bone marrow edema with osteoarthritis and temporomandibular joint (TMJ) internal derangement disorders.

METHODS

A literature search was performed using electronic databases PubMed/Medline (National Library of Medicine, Bethesda, Maryland) and Cochrane for articles published during the last 15 years (January 2000-December 2014). A predetermined inclusion and exclusion criteria were used for filtering the scientific papers. Research articles fulfilling the basic inclusion criteria were included in the review.

RESULTS

The reviewed studies showed that bone marrow edema is found in painful joints with osteoarthritis in a majority of cases. A few cases with no pain or significant degenerative changes are reported to have a bone marrow edema pattern as well.

CONCLUSIONS

Bone marrow edema, increased fluid level, and pain are associated with osteoarthritis in the majority of patients reporting TMJ arthritis. Degenerative and disc displacement conditions are multifactorial and require further investigations. Magnetic resonance imaging can be employed to detect bone marrow edema even in the absence of pain and clinical symptoms in the patients of internal derangements.

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.

Magnetic resonance imaging of temporomandibular joint: morphometric study of asymptomatic volunteers

BACKGROUND

The aims of this study were to determine the best suited magnetic resonance imaging scanning plane, scanning sequence, and imaging modality for the evaluation of the temporomandibular joint (TMJ) and quantitatively assess the relationship of articular disk position to condyle position.

METHODS

One hundred four TMJs in 52 symptom-free heads were examined by magnetic resonance imaging. The best scanning plane, scanning sequence, and scanning parameter were determined according to the imaging time and image quality. Bilateral symmetry of the articular disk and mandibular condyle was measured by using the automatic measurement of 3.0-T GE Excite Signa MR scanner.

RESULTS

Fast spin-echo sequence, oblique sagittal imaging plane, and proton density imaging were the best suited scanning sequence, scanning planes, and imaging modality, respectively. The thicknesses of the anterior and posterior bands and for the intermediate zone were not statistically different for both sides. The posterior band of the disk was found to originate in an area adjacent to the 12-o'clock position of the condyle (± 5 degrees), whereas the anterior band of the disk originated adjacent to 1-o'clock position (28 ± 6 degrees). The anteroposterior diameter and mediolateral diameter of the condylar processes were not statistically different for both sides. The axial condylar angle between the plane of the greatest mediolateral diameter of the condylar processes and the midsagittal plane were also not statistically different for both sides.

CONCLUSIONS

The magnetic resonance images can depict clearly major regional anatomic structures and position in the TMJ, which can be used in the early diagnosis for the TMJ disorder.

Correlation between clinical symptoms and magnetic resonance imaging findings in patients with temporomandibular joint internal derangement

Objectives

The purpose of this study was to clarify which findings in magnetic resonance imaging (MRI) are good predicators of pain and mouth opening limitation in patients with temporomandibular joint (TMJ) internal derangement (ID).

Materials and Methods

Clinical examinations for pain and mouth opening limitation were conducted for suspected TMJ ID. MRI scans were taken within a week of clinical examinations. On the oblique-sagittal plane image, readings were obtained in terms of the functional aspect of disc position, degree of displacement, disc deformity, joint effusion, and osteoarthrosis. Multiple logistic regression analyses were conducted to identify the predictors of pain and mouth opening limitation.

Results

A total of 48 patients (96 TMJs) were studied, including 39 female patients and 9 male patients whose ages ranged from 10 to 65 years. The resultant data showed significant correlations between pain and the MR imaging of the degree of disc displacement (P<0.05). The probability of there being pain in moderate to significant cases was 9.69 times higher than in normal cases. No significant correlation was found between mouth opening limitation and MRI findings.

Conclusion

We identified a significant correlation between clinical symptoms and MRI findings of ID. The degree of anterior disc displacement may be useful for predicting pain in patients with TMJ ID.

Analysis of Criteria for MRI Diagnosis of TMJ Disc Displacement and Arthralgia

Aims. To improve diagnostic criteria for TMJ disc displacement (DD). Methods. The standard protocol for MRI diagnosis of DD, using a 12 o'clock reference position, was compared to an alternative protocol. The alternative protocol involves the functional relationship between the condyle and articular eminence, using a line perpendicular to the posterior slope of the eminence as a reference for disc position. The disc location was examined using both protocols, and disc diagnoses were compared in their relationship with joint pain. Statistical analyses included P value, sensitivity, specificity, odds ratio, and kappa statistic. Results. 58 MRIs were interpreted. 36 subjects reported arthralgia; 22 did not. Both protocols demonstrated significance (standard P = 0.004, alternative P < 0.001) for the ability to predict arthralgia. The odds of arthralgia increased in DD patients diagnosed by standard methods 9.71 times and in DD diagnosed by alternative means 37.15 times. The diagnostic sensitivity decreased 30% using the alternative versus the standard protocol (0.6389 versus 0.9444), while specificity increased 60% (0.9545 versus 0.3636). Conclusions. A stronger relationship occurs between DD and arthralgia when using a function-based protocol. The alternative protocol correctly identifies subjects without arthralgia, who by standard methods would be diagnosed with DD, as having nondisplaced discs, providing a more clinically relevant assessment of TMJ disc displacement.

Disk and joint morphology variations on coronal and sagittal MRI in temporomandibular joint disorders

OBJECTIVES

This study aims to assess the disk morphology and the condyle position in subjects with temporomandibular (TMJ) disk displacements on sagittal and coronal magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Seventy-four TMJs (from 37 patients) with positive clinical TMD symptoms according to the RDC/TMD axis I protocol were evaluated by 1.5 T MRI. Disk position, disk morphology, sagittal and coronal condyle position, joint effusion, joint space, and coronal condyle angulation were evaluated. Multivariate logistic regression was used to explore the relationship between disk displacement and MRI variables.

RESULTS

Disk displacement with reduction (DDR) was found in 36.48 % and without reduction (DDwR), in 21.62 % of the joints. Disk displacement was anterior in 35.1 %, anterior-medial in 13.5 %, and anterior-lateral in 9.45 % of cases. The thickened posterior band (94.48 OR, p = 0.001) and the posterior condyle position (4.57 OR, p = 0.03) were more likely found on sagittal MRI in disk displacements. On coronal slices, the disk displacement was significantly associated with the distance from the most medial condyle point to the midplane (p < 0.05).

CONCLUSIONS

Disk displacement is associated with changes of disk shape, disk dimension, and condyle position on sagittal MRI. A significant variation of the distance from the most medial condyle point to the midplane in disk displacement was found on coronal MRI.

CLINICAL RELEVANCE

Our study highlights the existence of changes on coronal MRI in TMD patients which should be assessed for better understanding of the clinical evolution of temporomandibular disorders.

Localization of basicranium midline by submentovertex projection for the evaluation of condylar asymmetry

The purpose of this research was to compare the reliability of two different methods for cranial midline localization through cephalometric analysis of mandibular condyle asymmetries. A retrospective cohort study was performed analyzing consecutively the SMV radiograms of 47 patients undergoing oral surgery before orthodontic treatment at the Dental School, University of Trieste (Italy) from 2003 to 2008. Two different cephalometric analyses were used to identify the basicranium midline (Tracing 1: initial landmarks = craniostat ear rods; Tracing 2: initial landmarks = spinosum foramina), and the left/right symmetry ratio (SR) for four parameters (condylar length, condylar angle, intra-condylar hemidistance, extra-condylar hemidistance) was calculated. The main result showed that no significant statistical difference between the SRs of the intra-condylar and extra-condylar hemidistance obtained with the same tracing was found (t-test; P = NS; C.I. 95%). Conversely, the difference between the SRs obtained with the two different tracings was statistically significant (t-test; P < 0.000; C.I. 95%). In conclusion, if the analysis of condylar asymmetries is performed in growing subjects, utilization of anatomic references such as the neurovascular foramina seems to guarantee a lower error compared to non-fixed references such as ear rods.

Three-dimensional localization of impacted teeth using magnetic resonance imaging

Impacted teeth remain embedded in the jawbone beyond the normal eruption time with completed root growth. They can often get infected or damage neighboring teeth. Information about the three-dimensional position of impacted teeth is invaluable in orthodontic diagnosis and treatment planning. The purpose of this prospective study was to assess the feasibility of using magnetic resonance imaging (MRI) for the three-dimensional localization of impacted teeth in children and adults. The study included 39 patients from the pediatric age group with different tooth impactions and seven adults with impacted wisdom teeth. MRI yielded a clear separation between impacted teeth and the surrounding tissue, and the position and angulation of impacted teeth in all three spatial dimensions could be assessed. Compared to conventional radiography, dental MRI provides the advantage of full volumetric morphology accompanied by complete elimination of ionizing radiation, which is particularly relevant for repeated examinations of the pediatric group.