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Background: During physiological function of the temporomandibular joint, we have to rely only on elastic structures (in particular the bilaminar zone) for repositioning of the articular disc. A real muscle, however, would be functionally more reasonable. In patients, a decrease of this elasticity is possibly one of the reasons for temporomandibular joint malfunctions, which affect between 16% and 36% of the population., Method: This study assesses the morphogenesis of the murine (Mus musculus) temporomandibular joint with particular regard to the masticatory muscles, to throw light on this topic. To that end, a collection of 11 murine heads ranging from prenatal stages E13.25 to E20 was used and early postnatal stages P0 to P4, which were prepared as histological sections (thickness 8-10 µm) and stained conventionally in order to examine them with light microscopy. Next, the temporomandibular joint and selected surrounding structures, along with the masticatory muscles, were threedimensionally reconstructed using analySIS® software. Subsequently, specific morphometric analyses were performed., Results and Conclusions: The evaluation of the results led to the following conclusions., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021. Published by Elsevier GmbH.)

Objective: To compare and evaluate the signal-to-noise ratio (SNR) and the contrast-to-noise ratio (CNR) values between a 15-channel phased array head coil and 6-channel dS Flex M surface coil in the MRI of temporomandibular joint., Methods: 300 patients were randomly assigned to two groups: 150 patients were examined by using a 15-channel phased array head coil and the other 150 patients were scanned by using a 6-channel dS Flex M surface coil. All of the data were set in the same 6 regions of interest including the temporal lobe, condyle neck, lateral pterygoid muscle, parotid gland, the adipose area and an area of the background noise）. SNR and CNR values were measured respectively., Results: The numerical variation law of SNR and CNR values measured in regionsof interest of each group was similar, although different coils were used. There were statistically significant differences of SNR values in all of the oblique sagittal (OSag) proton density-weighted imaging, the part of OSag T 2 weighted image ( T 2 WI) except for SNR 4 and SNR 5 . and oblique coronal (OCor) T 2 WI sequence except for SNR 2 . On the contrary, SNR 4 and SNR 5 values in the OCor T 2 WI and SNR 5 values in OSag T 2 WI sequences by using the surface coil were higher than those by using the head coil. There were no statistically significant intergroup differences of CNR values in OSag proton density-weighted imaging sequence except CNR 1 and in OSag T 2 WI sequence except CNR 5 . But, statistically significant differences of all the values in the OCor T 2 WI sequence except for CNR 1 were observed., Conclusion: Both the phased array head coil and dS Flex M surface coil can be used for temporomandibular joint MRI.

Objective: The aim of this anatomical study was to determine if a needle is able to reach the lateral pterygoid muscle during the application of dry needling technique., Methods: A dry needling approach using 2 needles of 50 to 60 mm in length, one inserted over the zygomatic process posterior at the obituary arch (for the superior head) and other inserted below the zygomatic process between the mandibular condyle and the coronoid process (for the inferior head), was proposed. A progressive dissection into 3 stages was conducted into 2 heads of fresh male cadavers. First, dry needling of the lateral pterygoid muscle was applied on the cadaver. Second, a block dissection containing the lateral pterygoid was harvested. Finally, the ramus of the mandible was sectioned by osteotomy to visualize the lateral pterygoid muscle with the needle placements., Results: With the needles inserted into the cadaver, the block dissection revealed that the superior needle reached the superior (sphenoid) head of the lateral pterygoid muscle and the inferior needle reached the inferior (pterygoid) head of the muscle. At the final stage of the dissection, when the ramus of the mandible was sectioned by osteotomy, it was revealed that the superior needle entered into the belly of the superior head of the lateral pterygoid muscle., Conclusions: This anatomical study supports that dry needling technique for the lateral pterygoid muscle can be properly conducted with the proposed approach., (Copyright © 2015 National University of Health Sciences. Published by Elsevier Inc. All rights reserved.)

To investigate how absorbed doses to mastication structures in modern radiotherapy (RT) technique for head and neck cancer (HNC) compared with earlier RT techniques and with published trismus tolerance doses. To compare the incidence of radiation-induced trismus by earlier and newer RT techniques. This study investigated two HNC patient cohorts treated with RT in 2007–2012 (three-dimensional conformal radiotherapy [3DCRT] and/or intensity-modulated radiotherapy [IMRT]; n =121 [ Cohort 1 ]) and 2017–2020 (volumetric-modulated arc therapy [VMAT]; n =124 [ Cohort 2 ]). All patients underwent RT without mastication structure–sparing intent, had normal mouth-opening ability before RT, and were prospectively assessed. Trismus was defined as the maximal interincisal opening ≤35 mm at any follow-up (3-, 6-, and 12-months post-RT). The temporomandibular joints (TMJs), masseter, and medial/lateral pterygoid muscles were delineated on the planning CT:s. Mean doses were compared between cohorts, and evaluated with respect to published trismus tolerance doses. P values ≤ 0.05 indicated statistical significance. Within 12 months post RT, 74/121 (61%) of patients in Cohort 1 had experienced trismus compared to 11/124 (9%) in Cohort 2. Averaged mean doses (±S.D.) for the masseter muscles were 35.2±8.3 Gy in Cohort 1 and 20.2±8.7 Gy in Cohort 2 (P <0.001). Corresponding numbers were 19.1±16.2 and 4.3±4.3 Gy for the TMJs, 53.7±10.1 and 40.2±16.8 Gy for the medial pterygoid muscles, and 29.2±18.7 and 9.2±8.4 Gy for the lateral pterygoid muscles (all P <0.001). Masseter muscle doses were below tolerance doses in 23% of patients in Cohort 1 compared with 90% in Cohort 2. The corresponding numbers were 52% and 96% for the TMJs, 8% and 36% for the medial pterygoid muscles and 72% and 100% for the lateral pterygoid muscles. Mastication structure mean doses by more recent RT techniques were generally below proposed tolerance doses, with dose reductions of 10–20 Gy compared with earlier techniques. Modern RT without mastication-structure-sparing intent resulted in below 10% of HNC patients experiencing trismus compared with 60% treated with earlier techniques. • Modern radiotherapy can substantially spare organs-at-risk in head and neck cancer. • Mastication-structure mean radiation doses were reduced by 10–20 Gy. • These dose reductions were accompanied by a trismus reduction from 60% to 10%. [ABSTRACT FROM AUTHOR]

The temporomandibular joint (TMJ) is a distinguishing feature of mammals, and in most mammals includes an articular disc that buffers the loads placed on it by mastication. The disc is well developed in mammals with significant lateral masticatory jaw movements but is absent in toothless mammals, including extant monotremes, although histological studies of developing monotremes have shown rudimentary discs that fail to mature. Platypus (Ornithorhynchus anatinus) grind their food between keratinous pads in the maxillae and lower jaws and are the only edentulate mammals that masticate their food. In this study, we characterize the anatomy of the TMJ of the adult platypus to see if we can reconcile the anatomy, including the absence of the articular disc, with the mandibular movements observed in video recordings. We studied the gross anatomy of the maxillofacial region and the microstructure using microcomputed tomography (micro‐CT) and histological examination. Platypuses had well‐developed masticatory muscles but lacked an articular disc between the mandibular condyle and glenoid fossa. The surface of the glenoid fossa was slightly concave than that of the condylar head was correspondingly slightly convex. The pre‐ and postglenoid processes were not well developed. Micro‐CT showed dense trabecular bone in the anterior part of the condyle, where the lateral pterygoid muscle attached. Histological analysis showed that the surfaces of the condyle and glenoid fossa consisted of dense, avascular and thickened fibrous connective tissue. In addition, well‐developed synovial folds were present. These anatomical characteristics are consistent with both anterior and lateral movements of the mandible, while the thick layer of connective tissue substitutes for a disc by absorbing the mechanical stresses associated with mastication. The failure of the disc primordium to develop cannot be attributed to a lack of muscle development, but the distribution of stresses in the toothless platypus jaw is likely to be different from those in a masticating eutherian. [ABSTRACT FROM AUTHOR]

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This study aimed to predict dental freeway space by examining the clinical history, habits, occlusal parameters, mandibular hard tissue movement, soft tissue motion, muscle activity, and temporomandibular joint function of 66 participants. Data collection involved video-based facial landmark tracking, mandibular electrognathography, surface electromyography of mandibular range of motion, freeway space, chewing tasks, phonetic expressions, joint vibration analysis, and 3D jaw scans of occlusion. This resulted in a dataset of 121 predictor features, with freeway space as the target variable. Six models were trained on synthetic data ranging from 500 to 25,000 observations, with 65 original observations reserved for testing: Linear Regression, Random Forest, CatBoost Regressor, XGBoost Regressor, Multilayer Perceptron Neural Network (MPNN), and TabNet. Explainable AI indicated that key predictors of freeway space included phonetics, resting temporalis muscle activity, mandibular muscle activity during clenching, body weight, mandibular hard tissue lateral displacements, and dental arch parameters. CatBoost excelled with a test error of 0.65 mm using 5000 synthetic data points, while a refined MPNN achieved the best performance with 25,000 synthetic data points and 121 unique predictors, yielding an absolute error of 0.43 mm on the 65 original observations. [ABSTRACT FROM AUTHOR]

Temporomandibular joint disorders (TMDs) are closely related to the masticatory muscles, but objective and quantitative methods to evaluate muscle are lacking. IDEAL-IQ, a type of chemical shift-encoded magnetic resonance imaging (CSE-MRI), can quantify the fat fraction (FF). The purpose of this study was to develop an MR IDEAL-IQ-based method for quantitative muscle diagnosis in TMD patients. A total of 65 patients who underwent 3 T MRI scans, including CSE-MRI sequences, were retrospectively included. MRI diagnoses and clinical data were reviewed. There were 19 patients in the normal group and 46 patients in the TMD group with unilateral disc displacement. The TMD group was subdivided into those with and without clenching. The right and left FF values of the masseter, medial, and lateral pterygoid muscles were measured twice by two oral radiologists on CSE-MRI, and the average value was used. FF measurements using CSE-MRI showed excellent intra- and inter-observer agreement (ICC > 0.889 for both). There were no statistically significant differences between the right and left FF values in the masseter, medial pterygoid, and lateral pterygoid of the normal group (p > 0.05). A statistically significant difference was found in the TMD group without clenching, in which the masseter muscle had a statistically significantly lower FF value on the disc displacement side (3.94 ± 1.61) than on the normal side (4.52 ± 2.24) (p < 0.05). CSE-MRI, which can reproducibly quantify muscle FF values, is expected to be a biomarker for objective muscle evaluation in TMD patients. The masseter muscle is expected to be particularly useful compared to other masticatory muscles, but further research is needed. [ABSTRACT FROM AUTHOR]

The article presents a rare case of acute malocclusion produced by a unilateral partial tear of the lateral pterygoid muscle and an up-to-date literature review of the pathology. A 37-year-old female was examined; her chief complaints were pain on the right side of the temporomandibular joint (TMJ) area and mastication impairment associated with major occlusal modifications and anterior open bite. After magnetic resonance imaging (MRI) and cone beam computed tomography (CBCT) of the TMJ and subsequent MRI for soft tissue, the final diagnosis was a partial right lateral pterygoid muscle tear. The case shows the value of combined imaging in temporomandibular disorders (TMD) and the importance of soft tissue evaluation in addition to articular examination, as the primary pathology might lie outside the joint. The authors' review of the current literature did not hitherto reveal a similar case. [ABSTRACT FROM AUTHOR]

Symptoms of temporomandibular dysfunction (TMD) may include pain in the muscles or restrictions opening the mouth. The aim of this study was to assess the effects of initial Aqualizer™ therapy. Group 1 received initial Aqualizer™ therapy before definitive hard splint; Group 2 received no initial therapy. Patients with arthrosis, partial/total prosthesis or undergoing splint therapy were excluded. Objective (temporomandibular joint palpation, temporomandibular joint auscultation, palpation of the chewing muscles, and mobility of the lower jaw) parameters were evaluated. The level of statistical significance was 5% (p < 0.05). In 53 patients (Group 1 n = 25; Group 2 n = 28), a significant improvement (p < 0.001) was found in Group 1 in pain on palpation (masseter muscle, temporal muscle, post-mandibular region, lateral pterygoid muscle, and suboccipital region), but no significant differences in jaw mobility were found. Aqualizer™ therapy produces significant improvement of primary symptoms. [ABSTRACT FROM AUTHOR]

Background: Disc displacement with reduction (DDwR) is among the common disc disorders of temporomandibular joint (TMJ), which can be managed conservatively by splint therapy. Anterior repositioning splint (ARS) is the most commonly prescribed splint by dental practitioners, but not getting a normal disc– condyle relationship always and other side effects lead to need of comparing with other occlusal splints. This review will help in informed decision-making by clinicians in choosing an appropriate splint type for patients. Aim: The aim is to compare the effectiveness of ARS in the management of DDwR with other occlusal splints for TMJ and muscle pain, TMJ noise, any adverse effects, regaining normal disc–condyle relationship. Materials and Methods: We followed published protocol in the International prospective register of systematic reviews. Databases were searched till May 2023 using different search strategies as per the database. Title and abstract screening, followed by full-text screening and data extraction with risk of bias, was done by two independent reviewers in Covidence. Outcomes were reported as risk ratio (RR) or mean difference (MD) for dichotomous or continuous outcomes, respectively, using RevMan 5.4 (Review Manager 5.4) software. We used a random effect model for statistical analysis. Certainty of evidence was assessed using the Grading of Recommendation, Assessment, Development, and Evaluation Guideline Development Tool (GRADEpro GDT) software. Results: A total of 1145 reports were found from a database search. After screening, four studies were included for systematic reviews. Other occlusal splints reported were sagittal vertical extrusion device and mandibular ARS, full hard stabilization splint of canine or centric stabilization type. Data of only two studies could be used for meta-analysis having 30 participants received ARS and 40 received other occlusal splints. We did not find evidence of any difference between ARS and other occlusal splints for TMJ clicking in short term (RR 1.25, 95% confidence interval [CI] 0.91-1.72) but a small difference in favor of other occlusal splint in long term (RR 2.40, 95% CI 1.04–5.55). No evidence of any difference was found between both treatments for TMJ pain in short term (MD-5.68, 95% CI-17.31–5.95) and long term (MD 0.00, 95% CI-2.86–2.86) and muscle pain in short term. The certainty of evidence for comparison of two treatments for different outcomes was of low or very low level. Conclusion: Evidence is uncertain that other occlusal splints reduced TMJ clicking slightly in comparison to ARS. For the remaining outcomes, no evidence of any difference was found between the two splints and it may be biased due to selection bias, inadequate blinding of participants, and outcome assessor. [ABSTRACT FROM AUTHOR]

The treatment of dentofacial deformities generally includes orthognathic surgery in which mandibular condyle changes following surgery are a common cause of relapse. This study investigated the changes in the mandibular condyle and related muscles to identify the factors that affected the changes in the mandibular condyle after orthognathic surgery in skeletal class II patients. This research studied 60 joints in 30 patients with skeletal class II dentofacial deformities who received surgical orthodontic treatment, including bilateral sagittal split ramus osteotomy, and underwent computed tomography before and after orthodontic treatment. The mandibular condyle, masseter, and medial pterygoid muscles were reconstructed and measured in 3D. Condylar positional and morphology changes, masseter and medial pterygoid muscle volume, temporomandibular joint (TMJ) pain, and distal segment movement were analyzed. The study observed that both the masseter and medial pterygoid muscle volumes decreased with statistical significance. The changes in the horizontal direction were positively correlated with the amount of movement. The findings indicated that mandibular condyle changes were significantly affected by the movement of the distal segment, the medial pterygoid muscle volume, and the direction of the distal segment, which influenced the treatment's long-term stability after orthognathic surgery. [ABSTRACT FROM AUTHOR]

Botulinum toxin type A (BTX-A) injection using nerve stimulation or electromyography for recurrent temporomandibular joint (TMJ) dislocation has been reported for several years. However, using the available equipment like a nerve stimulator or an electromyograph is uncommon, and ultrasound guidance is convenient and requires no additional resources. In this report, we used ultrasound as a tool to achieve BTX-A injections in a patient with a traumatic brain injury to treat her TMJ dislocation. One week after the injections, she had no more dislocation. She remained symptom free during the 3 months of follow-up, and her clinical symptoms improved without significant complications. This is the first report using ultrasound guidance for BTX-A injections to treat recurrent TMJ dislocation. This treatment is an effective and safe technique that could be performed timely and locally without referral to a center with electromyography facilities. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare the effectiveness of arthroscopic-assisted lateral pterygoid muscle release versus scarification of retrodiscal tissues in the treatment of temporomandibular joint internal derangement. A prospective, comparative, randomized clinical trial involved 16 patients with TMJ internal derangement. Arthroscopic assisted release of lateral pterygoid muscle was assigned to one group of patients (Group I). Group II patients received arthroscopic assisted scarification of retrodiscal tissues. Data collected through functional examination including visual analogue scale (VAS), maximum mouth opening, lateral excursion, and clicking sound immediately and after 3, 6, and 12 months. Pre- and post-operative MRI was used to assess disc position. The VAS scores decreased in both groups at the end of the follow-up period (0.45 vs 6.75, and 1.13 vs 6.50 in group I and II respectively; P<0.001). The maximum mouth opening improved to 32.9.50 ± 1.69 mm in group I, and 30.49 ± 0.93 in group II (P<0.001). Lateral excursion improved in both groups (P<0.001). Clicking sounds disappeared in all patients. Within the limitations of the study, it seems that arthroscopic assisted release of lateral pterygoid and scarification of retrodiscal tissues may be beneficial in management of anteriorly displaced discs that don't respond to conservative treatments. [ABSTRACT FROM AUTHOR]

Background: Temporomandibular joint disorders (TMDs) are the most common cause of non-odontogenic pain in the maxillofacial region. Internal derangement (ID) is one of the most prevalent causes of TMDs, and disc displacement is recognized as the most common ID. The masticatory muscles are among anatomical structures involved in TMDs that may be affected by ID. Objectives: This study aimed to evaluate the correlation between the masticatory muscle dimensions and ID of temporomandibular joints using magnetic resonance imaging (MRI). Patients and Methods: This cross-sectional study was conducted on the MRI images of 145 patients, retrieved from the archives of the MRI diagnostic and research center during 2020 - 2021. The patients were categorized into three main groups of normal disc position (NP) (n = 42), disc displacement with reduction (DDR) (n = 54), and disc displacement without reduction (DDWR) (n = 49). The maximum width and height of the masseter and medial pterygoid muscles and the maximum height and length of the superior and inferior heads of the lateral pterygoid muscle were measured on MRI images for each of the groups. Data were analyzed using t-test, Pearson's correlation test, ANOVA test, and Tukey's test (alpha < 0.05). Results: Significant differences were observed between the NP, DDR, and DDWR groups regarding the height (P < 0.001) and length (P< 0.001) of the superior head of the lateral pterygoid muscle; both parameters were significantly higher in the NP group, followed by the DDR and DDWR groups (P < 0.05). The dimensions of masticatory muscles were significantly greater in males than females (P < 0.05), except for the width of the medial pterygoid muscle (P = 0.064). The height of the masseter muscle (r = 0.190, P = 0.022) and the medial pterygoid muscle (r = 0.166, P = 0.046) was significantly correlated with age. Conclusion: Significant correlations were found between the height and length of the superior head of the lateral pterygoid muscle and ID of TMJ; the corresponding values were lower in the DDWR group compared to the DDR and NP groups, respectively. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to assess whether magnetic resonance imaging (MRI) texture features of the lateral pterygoid muscle can distinguish between rheumatoid arthritis (RA) and osteoarthritis (OA) of the temporomandibular joint (TMJ). Methods: The authors extracted 279 texture features from 36 patients with RA and OA from the region of interest set for the lateral pterygoid muscle on short tau inversion recovery (STIR) images using MaZda Ver.3.3. A total of 10 texture features were selected using Fisher's coefficients, as well as probability of error and average correlation coefficients. Data observed to have a non-normal distribution using the Kolmogorov-Smirnov test were compared using the Mann-Whitney U-test. Receiver operating characteristic (ROC) curves were used to assess the ability of the 10 texture features to distinguish RA and OA of the TMJ. Results: A total of 10 features (5 Correlation, 3 Run Length Nonuniformity, 1 Sigma, and 1 Teta) were selected from 279 texture features. These texture features revealed significant differences between the RA and OA groups (p < 0.01). The sensitivity, specificity, accuracy, and area under the ROC curve of the texture features for distinguishing RA from OA were 0.78-0.94, 0.89-1.0, 0.86-0.92, and 0.89-0.95, respectively. Conclusion: MRI texture analysis of the lateral pterygoid muscle may be useful for distinguishing between RA and OA of the TMJ. [ABSTRACT FROM AUTHOR]

The anterior displacement of the articular disc is the most frequent cause of pathological alterations in the TMJ. Although it is an extremely common pathology, there is no certainty about the aetiopathogenesis of this disease. The main aim of the present report is to describe new anatomical findings that could help clarifying the aetiopathogenesis of this disease and determine a typology of treatment based on the cause of the disease. All the operative records of patients who underwent arthroscopic osteoplasty of the medial TMJ wall in our centre from January 2021 to September 2021 were reviewed and analysed to identify specific anatomical features observed in every procedure. Fifty-two joints were included for analysis in this study. Twenty-two joints were classified as Wilkes stages II-III and 30 as Wilkes stages IV-V. The most common complication observed in our sample was the dysaesthesias found in the temporal and preauricular regions. Other complications observed were frontal branch paresis (n = 2), intraoperative bleeding (n = 1), and postoperative malocclusion (n = 1). The compression of the superior head of pterygoid lateral muscle (SPLM) on the medial bony wall and the consequent muscle atrophy could be key for the aetiology of the anterior TMJ disc displacement. Therapeutic actions on the osseous and muscular component in this anatomical area could improve the outcomes of patients affected by TMJ internal derangement. A meticulous dissection of the fascia of the superior fascicle of the lateral pterygoid muscle allows a remodelling of the bone surfaces with minimal complications [ABSTRACT FROM AUTHOR]

Temporomandibular disorders affect between 5% and 12% of the population and present with symptoms such as headache, bruxism, pain at the temporomandibular joint, jaw popping or clicking, neck pain, tinnitus, dizziness, decreased hearing, and hyperacuity to sound. Common signs on physical examination include tenderness of the pterygoid muscles, temporomandibular joints, and temporalis muscles, and malocclusion of the jaw and crepitus. The diagnosis is based on history and physical examination; however, use of computed tomography or magnetic resonance imaging is recommended if the diagnosis is in doubt. Nonpharmacologic therapy includes patient education (e.g., good sleep hygiene, soft food diet), cognitive behavior therapy, and physical therapy. Pharmacologic therapy includes nonsteroidal anti-inflammatory drugs, cyclobenzaprine, tricyclic antidepressants, and gabapentin. Injections of the temporomandibular joints with sodium hyaluronate, platelet-rich plasma, and dextrose prolotherapy may be considered, but the evidence of benefit is weak. A referral to oral and maxillofacial surgery is indicated for refractory cases. (Am Fam Physician. 2023; 107(1):52–58. Copyright © 2023 American Academy of Family Physicians.) Temporomandibular disorders affect between 5% and 12% of the population and present with symptoms such as headache, bruxism, pain at the temporomandibular joint, jaw popping or clicking, neck pain, tinnitus, dizziness, decreased hearing, and hyperacuity to sound. Common signs on physical examination include tenderness of the pterygoid muscles, temporomandibular joints, and temporalis muscles, and malocclusion of the jaw and crepitus. The diagnosis is based on history and physical examination; however, use of computed tomography or magnetic resonance imaging is recommended if the diagnosis is in doubt. Nonpharmacologic therapy includes patient education (e.g., good sleep hygiene, soft food diet), cognitive behavior therapy, and physical therapy. Pharmacologic therapy includes nonsteroidal anti-inflammatory drugs, cyclobenzaprine, tricyclic antidepressants, and gabapentin. Injections of the temporomandibular joints with sodium hyaluronate, platelet-rich plasma, and dextrose prolotherapy may be considered, but the evidence of benefit is weak. A referral to oral and maxillofacial surgery is indicated for refractory cases. [ABSTRACT FROM AUTHOR]

Purpose: Management of mandibular condylar fracture has invited a great deal of controversy in maxillofacial trauma care. In the orthopaedic literature, surgeons have exhaustively described the use of a 'hematoma block' technique during closed reduction (CR) of the ankle or other long bone fractures. Post-traumatic ankylosis of the temporomandibular joint (TMJ) is due to development and progression of the intra-articular hematoma. We improvised their technique for use during CR of mandibular condylar fractures. The desirable effects which can be achieved with our proposed 'novel TMJ hematoma nerve block' technique are evacuating the accumulated hematoma, blocking auriculotemporal and masseteric nerves which in turn causes relaxation of the lateral pterygoid muscle, all in all, favouring accurate anatomical reduction of the fracture. Method: Thirteen patients with isolated unilateral condylar fractures were subjected to our new technique. The parameters assessed were the amount of hematoma evacuated, pain in TMJ region during reduction and postoperative anatomic reduction on cone beam computed tomography (CBCT). Results: All the patients showed a significant reduction in pain and lowered post-reduction angulation between the proximal condylar and distal ramal segments. Conclusion: Our technique is minimally invasive, safe, simple to perform, yielding excellent anatomic reduction of the fracture fragments. [ABSTRACT FROM AUTHOR]

Abstract Objective The lateral pterygoid is vital in coordinating multidimensional jaw movements. Since a vector in three‐dimensional (3D) space is defined by two 3D points, the role of the lateral pterygoid in 3D jaw movements is defined by its origin and insertion. Reportedly, the lateral pterygoid is inserted into not only the pterygoid fovea but also into the medial surface of the condylar process. The objective was to investigate the morphological features of the region of the lateral pterygoid that inserted into the medial surface of the condylar process. Material and Methods Ten head halves of seven cadaveric donors were analyzed. In all specimens, the insertion area on the medial surface of the condylar process was measured based on microcomputed tomography images. Muscle fibers were separated into ≥50 small bundles, and positional relationships between the origins and insertions were investigated. Results Overall, 28.8 ± 5.0% of the insertion area of the lateral pterygoid was situated on the medial surface of the condylar process. Moreover, muscle fiber arrangement revealed that origins of the muscle bundles inserting into the medial surface in seven specimens posteriorly occupied the lateral plate of the pterygoid process longitudinally, whereas those in three specimens mainly occupied the posteroinferior portion. Conclusions Muscle bundle inserting on the medial surface of the condylar process had a broad insertion area and a distinct origin on the posterior region of the lateral plate of the pterygoid process. This muscle bundle could act as one of the significant subunits within the lateral pterygoid. Therefore, anatomical coordination mechanisms underlying jaw movement cannot be elucidated without considering this subunit.

Background: Temporomandibular disorder (TMD) is the main cause of non-dental pain in orofacial area. The most common symptoms of TMD are joint pain, joint sound and limitation of jaw function. Botulinum toxin (BTX) injection is considered a potential treatment for TMD due to its pain-relieving properties and its ability to reduce muscle activity. Most of the studies are case series and further investigations are required to prove the efficacy of this treatment modality. Thus, in this study, we aimed to investigate the effect of BTX-A injection on the lateral pterygoid (LP) muscle and to evaluate its efficacy regarding TMD. Materials and methods: Thirty-eight patients (19 women and 19 men; mean age of 26.53 years) with painful unilateral temporomandibular joint click and LP muscle tenderness were enrolled in this study. They were divided into two groups; one received an extraoral BTX-A injection in the LP muscle, and the other received a placebo injection. Pain severity, jaw movements, click severity, and Helkimo index were recorded at the first visit, as well as one week, one month, and three months after the intervention. Data were analyzed using repeated-measures analysis of variance and t-tests. Results: The results showed that click severity was not significantly different between the BTX-A and placebo groups (P = 0.07). Pain and Helkimo index decreased significantly in the BTX group (P = 0.00 and P = 0.006, respectively); however, there was no significant difference between the two groups (P = 0.22 and P = 1, respectively). There was a significant difference in lateral movements between the groups (P = 0.00) but not in protrusive movement (P = 0.095). Conclusions: It can be concluded that although some studies have stated that BTX injection can make the click sound disappear, in this study, we did not find a significant difference between the two groups. Furthermore, our results showed that click and pain severity decreased, but the difference was not statistically significant. Therefore, further studies with a higher dosage of BTX and more participants are recommended. Trial registration The local Ethics Committee of Shiraz University of Medical Sciences approved this research (IR.SUMS.REC. 01/10/2018 and IRCT20130521013406N3). [ABSTRACT FROM AUTHOR]

Objective: This study explored the effect of qat chewing (QC) on the lateral pterygoid muscle (LPM), using magnetic resonance imaging (MRI).Methods: Forty qat chewers (QG), divided into three subgroups, according to duration of QC, and 20 non-qat chewers (NQG) were included. MRI sections were obtained to assess hypertrophy and atrophy of the superior belly (SB) and inferior belly (IB) of the LPM on the chewing and contralateral non-chewing side.Results: There was a significantly higher prevalence of atrophy of the IB (p < 0.001) and hypertrophy of the SB and IB (p = 0.002) in the QG. Hypertrophy of SB and IB was marked (p = 0.001) on the chewing side. Conversely, SB atrophy was marked on the non-chewing side (p = 0.003). MRI demonstrated a positive correlation between LPM alterations and the duration of QC in subgroup analysis.Conclusion: Unilateral QC might be a cause of LPM alterations. [ABSTRACT FROM AUTHOR]

To evaluate the diagnostic efficacy of CBCT–MRI fused image for anterior disc displacement and bone changes of temporomandibular joint (TMJ), which are the main imaging manifestations of temporomandibular disorders (TMD). Two hundred and thirty-one TMJs of 120 patients who were diagnosed with TMD were selected for the study. The anterior disc displacement, bone defect and bone hyperplasia evaluated by three experts were used as a reference standard. Three residents individually evaluated all the three sets of images, which were CBCT images, MRI images and CBCT-MRI fused images from individual CBCT and MRI images in a random order for the above-mentioned three imaging manifestations with a five-point scale. Each set of images was observed at least 1 week apart. A second evaluation was performed 4 weeks later. Intra- and interobserver agreements were assessed using the intraclass correlation coefficient (ICC). The areas under the ROC curves (AUCs) of the three image sets were compared with a Z test, and p < 0.05 was considered statistically significant. One hundred and forty-five cases were determined as anterior disc displacement, 84 cases as bone defect and 40 cases as bone hyperplasia. The intra- and interobserver agreements in the CBCT-MRI fused image set (0.76–0.91) were good to excellent, and the diagnostic accuracy for bone changes was significantly higher than that of MRI image set (p＜0.05). CBCT-MRI fused images can display the disc and surrounding bone structures simultaneously and significantly improve the observers' reliability and diagnostic accuracy, especially for inexperienced residents. [ABSTRACT FROM AUTHOR]

The aim of the study was to examine lateral pterygoid muscle (LPM) and temporomandibular joint (TMJ) disc before and after Le Fort I osteotomy with and without intentional pterygoid plate fracture and sagittal split ramus osteotomy (SSRO) in class II and class III patients. Le Fort I osteotomy and SSRO were performed in class II and class III patients. LPM measurements using oblique sagittal computed tomography (CT) images and TMJ disc position using magnetic resonance imaging (MRI) were examined. Statistical comparisons were performed for the LPM and TMJ between class II and class III patients and between those with and without intentional pterygoid plate fracture in Le Fort I osteotomy. The subjects comprised 60 female patients (120 sides), with 30 diagnosed as class II and 30 as class III. Preoperatively, the width of the condylar attachment, width at eminence, length of the LPM, angle of the LPM, and square of the LPM were significantly smaller in the class II group than in the class III group (p < 0.05). After 1 year, the width of the condylar attachment, width at eminence, and angle of the LPM remained significantly smaller in the class II group than in the class III group (p < 0.0001). TMJ disc position was significantly related to the width of the condylar attachment of the LPM, both pre- and postoperatively (p < 0.0001). However, postoperative disc position did not change in all patients. Next, the class II patients (60 sides) were divided into two groups who underwent Le Fort I osteotomy with or without intentional pterygoid plate fracture. Changes in all measurements of the LPM showed no significant differences between these two groups. Our study suggested that TMJ disc position classification could be associated with the width of condylar attachment of the LPM before and after surgery, while the surgical procedure, including Le Fort I osteotomy with intentional pterygoid plate fracture, might not affect postoperative LMP or disc position in class II patients. [ABSTRACT FROM AUTHOR]

The lateral pterygoid muscle (LPM) is intimately related with the temporomandibular joint (TMJ), playing an important role in its physiology. This makes it of interest to researchers who investigate temporomandibular disorders. The literature indicates that anatomical variations exist in the insertion of the superior fascicle of the LPM. Imaging and cadaver studies have revealed that the LPM may present an accessory fascicle. The study object was to carry out macroscopic analysis of the LPM, examining the origin and insertion of its superior and inferior fascicles. The study used 38 half-heads of adult individuals fixed in formaldehyde 10 %. To carry out macroscopic analysis of the LPM, an initial incision was made along the lower margin of the zygomatic arch; the origin of the masseter muscle was then dissected, separating its insertion on the lateral face of the mandibular ramus and retracting the muscle to posteroinferior. Two incisions were made on the zygomatic arch and the insertion of the temporal muscle on the coronoid process was identified with dissection pincers; it was dissected to gain access to the infratemporal fossa and the two fascicles of the LPM. The superior fascicle (SF) originated on the infratemporal face of the greater wing of the sphenoid, and on the superior third of the lateral face of the lateral lamina of the pterygoid process of the sphenoid in 26 samples. In 12 samples, it originated on the greater wing of the sphenoid and the infratemporal crest of the sphenoid. Type I insertion was found in 20 samples, Type II in 6 samples and Type III in 12 samples. In all the samples analysed, the inferior fascicle (IF) originated on the inferior two thirds of the lateral face of the lateral lamina of the pterygoid process and on the lateral face of the pyramidal process of the palatine, with insertion on the pterygoid fovea. The accessory fascicle (AF) of the LPM was present in 6 samples. The AF originated on the greater wing of the sphenoid in 2 cases and inferior to the superior fascicle in 4 cases; its insertion was on the capsular disc complex in all cases. The results obtained in our study contribute anatomical data on the LPM in Brazilian adult individuals, with evaluation of its insertion points. [ABSTRACT FROM AUTHOR]

The purpose of this study was to explore the status of the lateral pterygoid muscle (LPM) after detachment in artificial temporomandibular joint replacement (TJR) surgery. Patient clinical and computed tomography imaging data were collected before and after unilateral artificial TJR with LPM detachment. The volume of the LPM on the operated and unoperated sides was measured before and after surgery (at 1, 3, 6, 12 months) using ProPlan CMF 3.0 software. The volumes of the LPM on both sides, the patient's mandibular movements, quality of life (QoL), and pain and diet scores (visual analogue scales) were evaluated and compared at the different follow-up stages. Ten patients were included in the study. After surgery, the volume of the operated LPM was significantly reduced to 60.78% at 3 months (P = 0.007), and gradually stabilized to 51.58% at 6 months (P = 0.025) and 54.68% at 1 year postoperative (P = 0.002). There were no significant LPM volume changes on the unoperated side (P = 0.67). Lateral movement of the operated joint was significantly reduced (P = 0.021) and correlated with the LPM volume change after surgical detachment (P = 0.042). The LPM shrank after detachment in the artificial TJR surgery and the muscle detachment affected the movement of the replaced joint. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the outcomes of temporomandibular joint (TMJ) arthroscopic and open disc repositioning procedures in the management of anterior disc displacement (ADD). All consecutive patients treated with arthroscopic (group I) or open (group II) disc repositioning between April 2014 and August 2018 were included prospectively. The patients were assessed clinically (1, 3, 6, 12, 24, and 36 months postoperative) and with magnetic resonance imaging (MRI). The statistical analysis was performed using IBM SPSS Statistics v.22.0; P < 0.05 was considered significant. A total of 177 patients (227 joints) were included: 104 patients (130 joints) in group I and 73 patients (97 joints) in group II. There were statistically significant improvements in pain score, clicking, quality of life, diet, and maximum inter-incisal opening when comparing pre- and postoperative clinical parameters within the two groups (P < 0.05 at all time-points for all clinical parameters); however, improvements occurred earlier in group I (at 1 month) than in group II (6 months). Postoperative MRI revealed an overall success rate of 98.1% in group I and 97.3% in group II. New bone formation was found in 70.2% in group I and 30.1% in group II. Arthroscopy may be a better choice for ADD patients, with the advantages of faster clinical improvement and recovery, minimal invasiveness, and better condylar remodelling. [ABSTRACT FROM AUTHOR]

Background: The pterygoid fovea on the mandibular neck is superomedial to the mandibular notch and serves to attach the lateral pterygoid muscle.Clinical presentation: During a retrospective cone beam computed tomography study, a 67-year-old male patient was found to exhibit a peculiar variant that contradicted normal anatomy. The patient's mandibular condyles were asymmetrical in terms of their shapes and sizes, although their lateral poles (lateral condylar tubercles) were both prominent. On the left side, the lateral condylar tubercle had a second, or accessory, pterygoid fovea, which was located outside the mandibular notch. Further, the left lateral pterygoid muscle was attached to the entire width of the mandibular condyle, including the accessory fovea.Clinical significance: Such rare anatomical variants lead to asymmetrical temporomandibular joints, although their occurrence has not previously been reported. Thus, they should be further documented in clinical studies of temporomandibular joint dysfunction.Abbreviations: LPM: Lateral pterygoid muscle; MC: Mandibular condyle; PF: Pterygoid fovea; TMJ: Temporomandibular joint; MCC: Mandibular condylar cartilage; MPR: Multiplanar Reconstruction; VC: Vascular canal. [ABSTRACT FROM AUTHOR]

A novel total temporomandibular joint replacement (TMJR) was developed with CADskills BV (Ghent, Belgium), aiming to achieve reinsertion of the (LPM) onto a scaffold in the implant. In order to investigate the possibility of reinsertion of the LPM, an animal experiment was conducted. An in vivo sheep experiment was conducted, which involved implanting sheep with a TMJR. Clinical parameters were recorded regularly and computed tomography (CT) scan images of two randomly selected sheep per scan were made at 1, 3, and 6 months. After 9.5 months, the sheep were euthanized, and CT scans of all animals were performed in order to evaluate the LPM's enthesis. A total of 13 sheep were implanted with a TMJR. One sheep was used as a sham. Radiographs revealed four outcome types of enthesis reconstruction. In four sheep, there was no reconstruction between the implant and the LPM. In three sheep, there was a purely soft tissue connection of 0.5–0.9 mm (average 0.7 mm) between the ostectomized bony LPM insertion and the implant's lattice structure. A combination of partial bony and partial soft tissue enthesis attachment (0.3–0.5 mm, average 0.4 mm) was found in three sheep. A bony ingrowth of the enthesis into the scaffold occurred in two sheep. A secondary bony connection between the mandible and the insertion of the LPM was found in 10 of 13 sheep. Four fossa components were found to be displaced, yet TMJ function remained in these ewes. The heterotopic ossification that was seen may be a confounding factor in these results. This in vivo experiment showed promising results for improving the current approach to TMJR with the possibility of restoring the laterotrusive function. The fossa displacement was considered to be due to insufficient fixation and predominant laterotrusive force not allowing for proper osseointegration. Further optimization of the reattachment technique, scaffold position and surface area should be done, as well as trials in humans to evaluate the effect of proper revalidation. [ABSTRACT FROM AUTHOR]

Objective: The lateral pterygoid is vital in coordinating multidimensional jaw movements. Since a vector in three‐dimensional (3D) space is defined by two 3D points, the role of the lateral pterygoid in 3D jaw movements is defined by its origin and insertion. Reportedly, the lateral pterygoid is inserted into not only the pterygoid fovea but also into the medial surface of the condylar process. The objective was to investigate the morphological features of the region of the lateral pterygoid that inserted into the medial surface of the condylar process. Material and Methods: Ten head halves of seven cadaveric donors were analyzed. In all specimens, the insertion area on the medial surface of the condylar process was measured based on microcomputed tomography images. Muscle fibers were separated into ≥50 small bundles, and positional relationships between the origins and insertions were investigated. Results: Overall, 28.8 ± 5.0% of the insertion area of the lateral pterygoid was situated on the medial surface of the condylar process. Moreover, muscle fiber arrangement revealed that origins of the muscle bundles inserting into the medial surface in seven specimens posteriorly occupied the lateral plate of the pterygoid process longitudinally, whereas those in three specimens mainly occupied the posteroinferior portion. Conclusions: Muscle bundle inserting on the medial surface of the condylar process had a broad insertion area and a distinct origin on the posterior region of the lateral plate of the pterygoid process. This muscle bundle could act as one of the significant subunits within the lateral pterygoid. Therefore, anatomical coordination mechanisms underlying jaw movement cannot be elucidated without considering this subunit. [ABSTRACT FROM AUTHOR]

Objectives: The aim of this study was to evaluate lateral pterygoid muscle (LPM) signal intensity changes related to different degrees of disc status groups using magnetic resonance imaging (MRI). Methods: Four groups were established according to disc displacement of examined temporomandibular joint (TMJ) and opposing TMJ. MRI scans were obtained with a 1.5 T device. The signal intensity was measured from the sagittal slice where midportion of the muscle belly was observed. The regions of interest were placed over the superior and inferior heads of LPM. To normalize differences in signal intensity, signal intensity of the grey matter and white matter of the brain was also measured. Signal intensity ratio (SIR) was calculated. Measurements were performed in both T1- and T2-weighted images. Results: In the intergroup comparisons, a statistically significant difference was found for SIR1 sup., SIR1 inf., SIR2 sup. and SIR2 inf. variables (p < 0.01). According to multiple comparison test (Tukey), no significant difference was found between group 0 and group 1 for SIR1 sup., SIR1 inf., SIR2 sup. and SIR2 inf. variables (p > 0.05). For SIR1 sup., SIR1 inf., SIR2 sup. and SIR2 inf. variables, significant differences were found between five binary comparison groups (1–2, 1–3, 2–3, 0–2, 0–3) (p < 0.05). Conclusion: In conclusion, SIR is correlated with the degree of disc displacement. The internal derangement of the opposite joint did not affect SIR of superior and inferior heads of examined LPM in both T1- and T2-weighted images. The inferior head of LPM was also found affected by disc displacement. [ABSTRACT FROM AUTHOR]

The Lateral Pterygoid Muscle (LPM) is a complex and variable structure. Being able to determine its exact anatomy, neighboring relationships, origin and insertions, helps clinicians to better understand its function in the stomatognathic system. This review seeks to analyze the literature, in order to clarify the antagonistic function of the lateral pterygoid muscle heads, from a nervous point of view. Furthermore, the description of its origin, aspects of insertions and possible anatomical variations, its functions as reported in traditional literature, are analyzed and compared with original articles. Different electronic databases and books were analyzed, with designated inclusion and exclusion criteria. Two researchers independently reviewed the articles, whennecessary a third researcher resolved any differences. This review includes a total of 11 articles and 4 books related to our study topic. Results were reported using data extraction tables, which included functions, innervation, origin and insertion, and anatomical variations of the LPM. Our results show that the common elements of origin of LPM were clearly identified, but their insertion showed variations between the different studies, both in the percentage of fibers joined and the anatomical elements inserted. Considering the antagonistic functions of the two heads, authors have described it as two different muscles. However from a nervous point of view, this theory is not supported. Finally, understanding the functions of the LPM during its action is complex, since most studies available use cadavers or electromyography. Therefore, we believe that the development of less invasive and painful methodologies, would help to understand the influence of anatomical variations on the function of this muscle. [ABSTRACT FROM AUTHOR]

The aim of this study was to examine the lateral pterygoid muscle (LPM) parenchyma, myotendinous junction, and tendon in temporomandibular disorder (TMD) patients using 3T magnetic resonance imaging (MRI). Results were compared with findings reported in the literature, in which the LPM has been attributed a major role in triggering TMD. 3T MRI was used for temporomandibular joint (TMJ) imaging. The MRI images of 63 patients were analysed for muscle contracture and atrophy, tendon rupture, signal alterations of the tendon, tendon contrast enhancement, and peritendinous fluid collection. Descriptive statistics and the coefficient estimate method were used for statistical analysis. Focus was placed on the association between LPM tendon pathology and TMJ lesions like osteoarthritis and disc displacement. Severe lesions of the LPM tendon and muscle parenchyma, like rupture or fibrosis, were detected in very few cases. Only moderate signs of tendinosis were found in TMD patients. In contrast, there was a clear correlation between tendon lesions and osteoarthritis or anterior disc displacement. These results indicate the need to discuss and question the role of the LPM and its tendon in TMD. Data suggest that LPM and tendon lesions are part of complex degenerative changes of the TMJ, and it seems less likely that a LPM disorder is causative in TMD. [ABSTRACT FROM AUTHOR]

The temporomandibular joint is a highly conserved articulation because it promotes survival and propagation via the essential functions of mastication, communication, and routine mating success (dentofacial esthetics). The temporomandibular joint is a unique secondary joint formed between the endochondral temporal bone and the mandibular secondary condylar cartilage via Indian hedgehog and bone morphogenetic protein signaling that is closely related to ear development. A dynamic epigenetic environment is provided by Spry1 and Spry2 genetic induction of the lateral pterygoid and temporalis muscles. Mechanical loading of the condylar periosteum during fetal development produces a superficial layer of fibrocartilage that separates from the condyle to form the interposed temporomandibular joint disc. The articular surfaces of the condyle and fossa are dynamically modified periosteum that has healing and regenerative capability. This unique tissue is composed of a superficial fibrous layer (synovial surface) with an underlying proliferative (cambium) layer that produces a cushioning layer of fibrocartilage which subsequently forms bone. Prior to occlusion of the first primary (deciduous) molars at about 16 months, facial development is dominated by primary genetic mechanisms. After achieving posterior functional occlusion, biomechanics enhances temporomandibular joint maturation, and assumes control of facial growth, development and adaptation. Concurrently, hypothalamus control of musculoskeletal physiology shifts from insulin‐like growth factor IGF2 to IGF1, which affects bone via muscular loading (biomechanics). Three layers of temporomandibular joint fibrocartilage are resistant to heavy functional loading, but parafunctional clenching may result in degeneration that is first manifest as trabecular sclerosis of the mandibular condyle. [ABSTRACT FROM AUTHOR]

The Central Relation (CR) is a concept that defines the ideal position of the mandibular condyle in the mandibular fossa. The position has been the subject of much discussion in the literature, noting changes as advancements in knowledge and technology are achieved. Thus, certain essential anatomical elements that are used as a guide for the clinician, are taken into account. The importance of being able to identify this position lies in the correct execution of both diagnostic and treatment procedures in various areas of dentistry. There are anatomical elements of the temporomandibular joint (TMJ) that improve understanding of the CR concept. These include: Bone condensation of the functional articular surfaces and their fibrocartilage coating; the middle portion of the joint disc, devoid of vessels and nerves. The roof of the mandibular fossa can become extremely thin, so it would not be considered an area to support load; the posterior prolongation of the articular disc (AD) Which is highly vascularized and innervated. The AD is also closely related to structures such as the temporomandibular or lateral ligament and the superior head of the lateral pterygoid muscle. Along with the previously described elements, this would allow proper functioning of the TMJ. The correct learning and use of these concepts contributes to a better exercise in the professional development of students and professionals in the area of dentistry. [ABSTRACT FROM AUTHOR]

The temporomandibular joints and associated muscles allow the mandible to move in the three planes (sagittal, frontal and horizontal), in this way the jaw can perform complex mandibular movements. For several decades, mandibular border movements have been studied. However, studies were initially carried out in two dimensions (2D). At the present time, it is possible to analyze mandibular kinematics in three dimensions (3D), with the 3D electromagnetic articulograph (EMA). The objective of the study is to evaluate the mandibular border movements (sagittal, frontal and horizontal), using 3D electromagnetic articulation. In this analysis, 11 subjects 31.9 ± 5.7 years of age on average, participated (women 30.2 ± 2.9 and men 34.0 ± 7.8) completely dentate patients, from first to first molar, with no temporomandibular disorders or orthodontic pretreatment. Files were processed using scripts, developed in MATLAB®. Among the most relevant results, a statistical difference was found between men and women in relation to the Frontal area of Posselt polygon, and results of the sagittal polygon area of all the participants were greater than those reported in previous studies. [ABSTRACT FROM AUTHOR]

To investigate the effect of arthroscopic disc repositioning on condylar development and mandibular asymmetry in juvenile patients with unilateral temporomandibular joint (TMJ) anterior disc displacement (ADD). A retrospective cohort study was conducted on unilateral juvenile anterior disc displacement (UJADD) patients of 10–20 years of age treated in Shanghai Ninth People's Hospital from 2010 to 2017. The primary predictor was TMJ arthroscopic disc repositioning surgery, according to which patients were divided into a surgery group and a control group. Initial and re-examined (with at least 6-month interval) magnetic resonance imaging (MRI) and posteroanterior cephalometric radiographs (PA) were collected. The condylar heights on both sides of the TMJ were measured by MRI and the difference between them was calculated. Menton (Me) deviation was measured based on PA. Changes in condylar height difference and Me deviation were compared between the two groups. A total of 108 UJADD patients were collected in this study, including 55 patients in the surgery group and 53 patients in the control group. There were no significant differences in age, sex and follow-up time between the two groups. The condylar height difference was (−0.61 ± 2.02) mm in surgery group and (1.68 ± 1.73) mm in control group (P < 0.0001); while the Me deviation was (−1.00 ± 1.15) mm in surgery group and (1.81 ± 1.96) mm in control group (P < 0.0001), indicating that TMJ arthroscopic disc repositioning surgery could significantly improve condylar height difference and Me deviation. UJADD should be treated as early as possible, especially in juvenile patients, in order to improve condylar development and avoid jaw deformities. [ABSTRACT FROM AUTHOR]

The location of the terminal hinge axis of the temporomandibular joint is still a very wide-spread procedure in dentistry in order to replicate the movement in various articulator devices. Especially pantographic methods are claimed to provide accurate measurements and, additionally, are seen to be able to separate a pure rotation of the joint from a movement with an arbitrary combined shift and rotation. In the latter application, these methods were used in a lot of studies as a reference standard. The aim of this study was to analyze, whether common pantographic methods in general are able to distinguish between a pure rotation and a movement with rotational and translational portions. The mathematical proof of this analysis was done with theoretical kinematic considerations and compared with computer simulations. The results show for the first time that there exist combinations of rotational and translational movements of the temporomandibular joint which cannot be separated from pure rotational movements using actual pantographic methods. Even more, the consequence is a shifted location of the (combined) finite center (axis) of rotation in comparison to the true center (axis) of rotation: in case of a translational portion of only 1 mm, this is a displacement of around ±6 mm and, in case of 2 mm translation, a displacement of ±12 mm. This finding necessitates a critical reinterpretation of former studies using pantographic methods as a reference standard. Further, under some circumstances it may also affect the applicability of articulator concepts and the interpretation of functional signs. [ABSTRACT FROM AUTHOR]

The aim of this study is to reveal the morphological property about the loose bodies (LBs) of temporomandibular joint (TMJ) by scanning electron microscope (SEM). We obtained specimens from two female cases of released loose body by surgical operation. These specimens were fixed by soaking in a mixture of 5% glutaraldehyde or 4% formaldehyde for one week. They were cut into half pieces. These specimens were observed at an accelerating voltage of 3 kV under a SEM (JSM-5500, JEOL, Tokyo). In the electron microscopic findings, it seems to be separated into two different parts as inside part and outside part. On the inside part, collagen fibers were running very densely in the same direction in an orderly neatly manner. Whereas, we observed waved collagen fibers running irregularly with many spaces on the outside part. Outside part seems to be porous pattern compared with inside part. It might be that the surface and outside part included many active fibroblasts. As results, it seems that the LBs might develop in a multi-layer style, in which fibrous tissues were piled up loosely around the inside part. The proliferating activity of LBs grows from the inside to outside of SC in TMJ. [ABSTRACT FROM AUTHOR]

Objectives: Temporomandibular joint dysfunction (TMD) results in changes in anatomical structures. The aim of this study was to examine the morphological changes using magnetic resonance imaging (MRI) and evaluate the effectiveness of different treatment methods in patients with TMD. Methods: 34 TMD patients (18-62 years of age) were randomly divided into two treatment groups. Group A (n=18) was subjected to dry needling (DN) and mobilization for 10 sessions, Group B (n=16) was instructed to use occlusal splint with home exercises for one month. The control group included MRIs of 17 healthy adults that were randomly selected from the archives of Radiology Department of Mustafa Kemal University. The length and width of the masseter, lateral and medial pterygoid muscles and the depth of the mandibular fossa were measured and mandibular condyle types were recorded. Range of motion of each temporomandibular joint was evaluated in pre- and post-treatment periods to test the effectiveness of the treatment methods. Results: The size of the masticatory muscles in TMD group was significantly smaller than the control group (p<0.05). The depth of the mandibular fossa was significantly shallower in the TMD group (p<0.05). The most commonly encountered condylar shape was convex in the TMD group (63.6%), but flat (58.8%) in the control group. No statistically significant relationship was observed between condyle type and fossa depth (p>0.05). However, the fossa depth showed a significant correlation with muscle size (p<0.05) and this correlation decreased with dysfunction. Dry needling and mobilization significantly decreased pain and increased mandibular movements (p<0.05); however, there was no significant change for Group B. Conclusion: The anatomical structures associated with the temporomandibular joint seems to be affected in patients with TMD. We suggest that the limited movement of the temporomandibular joint may cause atrophy of the masticatory muscles, affecting the range of motion of the joint. Dry needling and mobilization techniques might be a more effective alternative than occlusal splint in the treatment of TMD. [ABSTRACT FROM AUTHOR]

Temporomandibular disorder is a clinical painful condition in the temporomandibular joint (TMJ) region. The purified sulfated polysaccharide from the green marine algae Caulerpa racemosa (Cr) has provided anti-inflammatory and antinociceptive activity. This study evaluated these effects on a TMJ hypernociception model. Wistar rats (180 - 250 g) were pre-treated (i.v.) with Cr at 0.01, 0.1, or 1 mg/kg or vehicle 30 min before formalin (1.5%/50 μL, i.art.), capsaicin (1.5%/20 μL, i.art.), or serotonin (225 μg/50 μL, i.art.) in the TMJ, and nociceptive behaviors were measured for 45 or 30 min upon inflammatory stimuli. Inflammatory parameters vascular permeability assay, TNF-α, and IL-1β by ELISA, protein expression of adhesion molecules ICAM-1 and CD55 by Western blot were assessed. The involvement of heme oxygenase-1 (HO-1) and nitric oxide (NO) pathways were assessed by pharmacological inhibition. Cr (1 mg/kg) reduced nociceptive behavior, plasmatic extravasation, TNF-α, and IL-1β levels, as well as ICAM-1 and CD55 expression in periarticular tissues. Cr antinociceptive effect was not prevented by aminoguanidine, but ZnPP-IX did reduce its antinociceptive effect. Therefore, Cr antinociceptive and anti-inflammatory effects in this experimental model of hypernociception depended on the HO-1 pathway integrity, as well as reducing peripheral inflammatory events, e.g., TNF-α and IL-1β cytokines levels, ICAM-1 and CD55 expression. [ABSTRACT FROM AUTHOR]

Background: Temporomandibular disorders (TMDs) are pathological conditions affecting the temporomandibular joint and/or masticatory muscles. The current diagnosis of TMDs is complex and multi-factorial, including questionnaires, medical testing and the use of diagnostic methods, such as computed tomography and magnetic resonance imaging. The evaluation, like the mandibular range of motion, needs the experience of the professional in the field and as such, there is a probability of human error when diagnosing TMD. The aim of this study is therefore to develop a method with infrared cameras, using the maximum range of motion of the jaw and four types of classifiers to help professionals to classify the pathologies of the temporomandibular joint (TMJ) and related muscles in a quantitative way, thus helping to diagnose and follow up on TMD.Methods: Forty individuals were evaluated and diagnosed using the diagnostic criteria for temporomandibular disorders (DC/TMD) scale, and divided into three groups: 20 healthy individuals (control group CG), 10 individuals with myopathies (MG), 10 individuals with arthropathies (AG). A quantitative assessment was carried out by motion capture. The TMJ movement was captured with camera tracking markers mounted on the face and jaw of each individual. Data was exported and analyzed using a custom-made software. The data was used to identify and place each participant into one of three classes using the K-nearest neighbor (KNN), Random Forest, Naïve Bayes and Support Vector Machine algorithms.Results: Significant precision and accuracy (over 90%) was reached by KNN when classifying the three groups. The other methods tested presented lower values of sensitivity and specificity.Conclusion: The quantitative TMD classification method proposed herein has significant precision and accuracy over the DC/TMD standards. However, this should not be used as a standalone tool but as an auxiliary method for diagnostic TMDs. [ABSTRACT FROM AUTHOR]

Osteoarthritis is a degenerative disease that causes substantial changes in joint tissues, such as cartilage degeneration and subchondral bone sclerosis. Chondroitin sulfate and glucosamine are commonly used products for the symptomatic treatment of osteoarthritis. The aim of the present study was to investigate the effects of these products when used as structure-modifying drugs on the progression of osteoarthritis in the rabbit temporomandibular joint. Thirty-six New Zealand rabbits were divided into 3 groups (n = 12/group): control (no disease); osteoarthritis (disease induction); and treatment (disease induction and administration of chondroitin sulfate and glucosamine). Osteoarthritis was induced by intra-articular injection of monosodium iodoacetate. Animals were killed at 30 and 90 days after initiation of therapy. The treatment was effective in reducing disease severity, with late effects and changes in the concentration of glycosaminoglycans in the articular disc. The results indicate that chondroitin sulfate and glucosamine may have a structure-modifying effect on the tissues of rabbit temporomandibular joints altered by osteoarthritis. [ABSTRACT FROM AUTHOR]

Objectives: Ageing could be a contributing factor to the progression of temporomandibular joint osteoarthritis (TMJ OA), whereas its pathogenesis and potential therapeutic strategy have not been comprehensively investigated. Materials and methods: We generated ageing mouse models (45‐week and 60‐week; 12‐week mice as control) and intermittently injected 45‐week mice with parathyroid hormone (PTH(1‐34)) or vehicle for 4 weeks. Cartilage and subchondral bone of TMJ were analysed by microCT, histological and immunostaining. Western blot, qRT‐PCR, ChIP, ELISA and immunohistochemical analysis were utilized to examination the mechanism of PTH(1‐34)'s function. Results: We showed apparent OA‐like phenotypes in ageing mice. PTH treatment could ameliorate the degenerative changes and improve bone microarchitecture in the subchondral bone by activating bone remodelling. Moreover, PTH inhibited phosphorylation level of Smad3, which can combine with p16ink4a gene promoter region, resulting in reduced senescent cells accumulation and increased cellular proliferation of marrow mesenchymal stem cells (MSCs). ELISA also showed relieved levels of specific senescent‐associated secretory phenotype (SASP) in ageing mice after PTH treatment. Conclusions: In summary, PTH may reduce the accumulation of senescent cells in subchondral bone by inhibiting p16ink4a and improve bone marrow microenvironment to active bone remodelling process, indicating PTH administration could be a potential preventative and therapeutic treatment for age‐related TMJ OA. [ABSTRACT FROM AUTHOR]