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BACKGROUND: TMJ morphology/position and trabecular structure are influenced by various factors. The role of the interincisal angle, an indicator of the anterior occlusal relationship, on TMJ remains unclear. This study aims to investigate the morphology, trabecular bone structure, and position of the condyle, as well as the glenoid fossa's morphology in skeletal class II populations with different interincisal angles. MATERIALS AND METHODS: A total of 150 adult patients with normodivergent facial types and skeletal class II malocclusions were selected and divided into three groups based on their interincisal angles: normal, small, and large angle groups. The indexes of TMJ were measured using cone-beam computed tomography (CBCT) data and analyzed using Dolphin Imaging, Mimics, and ImageJ. RESULTS: The small angle group had the smallest anteroposterior diameter (APD), while the large angle group had a greater mediolateral diameter (MLD). The large angle group exhibited significantly the largest maximum axial area, bone surface area, and bone volume (P < 0.05). Small and large angle groups exhibited greater bone trabeculae (Tb. N) and thinner trabecular thickness (Tb. Th). Compared to the normal angle group, the small angle group exhibited a larger horizontal condylar angle and smaller bilateral condylar angles on the axial plane, while the large angle group showed the opposite trend. Small and large angle groups showed a reduced vertical condyle angle on the coronal plane, with the largest reduction observed in the large angle group (P < 0.05). Small and large angle groups had higher heights of the glenoid fossa (GFH). The large angle group exhibited the greatest GFH and width of the glenoid fossa (GFW) (P < 0.05). CONCLUSION: The large angle group had elongated oval and large condyles, and deeper glenoid fossae, while a flattened-oval and smaller condyle, and wider and shallower glenoid fossae were observed in the small angle group. Small and large interincisal angle affects the structure of condylar trabeculae, resulting in thinner Tb. Th and greater Th. N. In the condylar position, small and large angle groups exhibit condylar rotation in the axial and coronal planes. Therefore, the interincisal angle affects the morphology, position, and trabecular structure of the TMJ. This implies that we must pay attention to the impact of the interincisal angle on TMJ, and it is crucial to restore the normal interincisal angle during orthodontic treatment.

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The temporomandibular joint (TMJ) ligaments play crucial roles in its function or dysfunction. The objective of this study was to describe the macro and microscopic morphology of these ligaments in domestic pigs, aiming to: (1) expand knowledge about the species; (2) provide anatomical references for advancing veterinary therapy and utilizing pigs as animal models in craniofacial research. Heads of young Sus scrofa domesticus were dissected to identify TMJ ligaments. Fragments of these ligaments were collected and processed for subsequent histological analysis with Haematoxylin and eosin staining. The results were qualitatively described. Pigs exhibited a TMJ reinforced by three individualized capsular ligaments: a lateral ligament, attaching to the ventral margin of the zygomatic process of the temporal bone and the lateral margin of the mandibular neck; a caudomedial ligament, attaching to the retroarticular process of the squamous part of the temporal bone and the caudomedial margin of the mandibular neck and a caudolateral ligament, attaching to the ventral margin of the base of the zygomatic process of the temporal bone and the caudal margin of the mandibular neck. The lateral ligament exhibited a greater constitution of dense irregular connective tissue, while the caudomedial and caudolateral ligaments showed a greater constitution of dense regular connective tissue. It is concluded that the TMJ of pigs presents one more ligament than horses, cattle, dogs, cats and what has been described for pigs themselves. We believe these results may contribute to the improvement of veterinary clinical and surgical therapy overall, as well as provide essential morphological information for a better interpretation and application of interspecies results in craniofacial research using pigs as an experimental model, as in the case of humans.

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BACKGROUND: Anterior displacement of the temporomandibular joint (TMJ) disc is the most typical pathological condition of TMJ disorders. Structures attached to the articular disc may support the disc in various directions and contribute to stabilizing the TMJ. However, the relationship between the articular disc, capsule, and masticatory muscles remains unclear. Therefore, this study aimed to clarify the relationship between the masticatory muscles, related masticatory fascia, articular disc, and capsule. METHODS: We examined 10 halves from adult Japanese cadavers, with five halves macroscopically analyzed and the remaining five histologically analyzed. The TMJ was dissected from the lateral aspect for gross anatomical analysis. For histological analysis, the relationship between the temporal and masseteric fasciae and the articular capsule was observed in the coronal section. Additionally, we evaluated relationships among the disc, capsule, temporal fascia, and masseteric fascia in 10 living and healthy volunteers using magnetic resonance imaging. RESULTS: The articular disc was attached to the capsule without a clear border. The capsule continued into the masseteric and temporal fasciae. Consequently, the articular disc, capsule, masseteric, and temporal fasciae were considered a single complex. CONCLUSIONS: The single complex of the temporalis, masseter, capsule, masticatory fascia, and disc may antagonize the force in the posterolateral direction through the fascia.

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The dual jaw joint of Morganucodon1,2 consists of the dentary-squamosal joint laterally and the articular-quadrate one medially. The articular-quadrate joint and its associated post-dentary bones constitute the precursor of the mammalian middle ear. Fossils documenting the transition from such a precursor to the mammalian middle ear are poor, resulting in inconsistent interpretations of this hallmark apparatus in the earliest stage of mammaliaform evolution1-5. Here we report mandibular middle ears from two Jurassic mammaliaforms: a new morganucodontan-like species and a pseudotribosphenic shuotheriid species6. The morganucodontan-like species shows many previously unknown post-dentary bone morphologies1,2 and exhibits features that suggest a loss of load-bearing function in its articular-quadrate joint. The middle ear of the shuotheriid approaches the mammalian condition in that it has features that are suitable for an exclusively auditory function, although the post-dentary bones are still attached to the dentary. With size reduction of the jaw-joint bones, the quadrate shifts medially at different degrees in relation to the articular in the two mammaliaforms. These changes provide evidence of a gradual loss of load-bearing function in the articular-quadrate jaw joint-a prerequisite for the detachment of the post-dentary bones from the dentary7-12 and the eventual breakdown of the Meckel's cartilage13-15 during the evolution of mammaliaforms.

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OBJECTIVES: Temporomandibular disorders (TMDs) are common and may cause persistent functional limitations and pain. Magnetic resonance imaging (MRI) at 1.5 and 3 T is commonly applied for the evaluation of the temporomandibular joint (TMJ). No evidence is available regarding the feasibility of modern low-field MRI for the assessment of TMDs. The objective of this prospective study was to evaluate the image quality (IQ) of 0.55 T MRI in direct comparison with 1.5 T MRI. MATERIALS AND METHODS: Seventeen patients (34 TMJs) with suspected intraarticular TMDs were enrolled, and both 0.55 and 1.5 T MRI were performed on the same day. Two senior readers independently evaluated the IQ focusing on the conspicuity of disc morphology (DM), disc position (DP), and osseous joint morphology (OJM) for each joint. We analyzed the IQ and degree of artifacts using a 4-point Likert scale (LS) at both field strengths. A fully sufficient IQ was defined as an LS score of ≥3. Nonparametric Wilcoxon test for related samples was used for statistical comparison. RESULTS: The median IQ for the DM and OJM at 0.55 T was inferior to that at 1.5 T (DM: 3 [interquartile range {IQR}, 3-4] vs 4 [IQR, 4-4]; OJM: 3 [IQR, 3-4] vs 4 [IQR 4-4]; each P < 0.001). For DP, the IQ was comparable (4 [IQR 3-4] vs 4 [IQR 4-4]; P > 0.05). A sufficient diagnostic IQ was maintained for the DM, DP, and OJM in 92% of the cases at 0.55 T and 100% at 1.5 T. Minor image artifacts (LS score of ≥3) were more prevalent at 0.55 T (29%) than at 1.5 T (12%). CONCLUSIONS: Magnetic resonance imaging of the TMJ at 0.55 T yields a lower IQ than does MRI at 1.5 T but maintains sufficient diagnostic confidence in the majority of patients. Further improvements are needed for reliable clinical application.

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BACKGROUND: The temporomandibular joint is one of the most complex anatomic structures. It takes a great role in masticatory system and helps to make possible some functions such as speaking, chewing and swallowing. Clinicians should have sufficient anatomical knowledge to assess relationships of the hard and soft tissues, including the mandibular condyle, glenoid fossa, articular eminence of the temporal bone, the articular disc and its attachments. The aim of this study was to evaluate the frequency of different types of mandibular condyles and its distribution according to the age and gender. It was also evaluated whether the condyle types were bilaterally symmetrical or not. MATERIALS AND METHODS: A total of 1315 digital panoramic images which obtained from the patients suffering from the dental problems were assessed. Demographic data, condylar morphology were noted. All obtained data were analysed by using descriptive statistics. Morphology of mandibular condyles were classified into four shapes as identified in other studies, namely: type I - oval shape, type II - diamond shape, type III - bird beak shape, type IV - crooked finger shape. Two independent examiners, who have 19 and 7 years of experience in oral and dentomaxillofacial radiology, made a consensus and evaluated all images. RESULTS: A total of 1315 digital panoramic images were assessed. Seven hundred sixty-seven [58.3%] the patients were female and 548 [41.6%] were male. The age range of patients was from 18 to 84 years. Right-left condyle types were found to be symmetrical in the range of 67% of the subpopulation examined in the study. For the consensus, 'oval' condyle was common on both the right and left, while 'crooked finger' condyle was the rarest. CONCLUSIONS: The temporomandibular joint is the most important structure for all jaw functions such as speech, swallowing. In order for all these functions to continue in a healthy way, the anatomical structure should be known very well down to the finest detail. Identification of anatomical structures and their variations can play an important role in implant dentistry. Clinicians commonly prefer conventional radiologic methods to evaluate dentomaxillofacial region. Although the most of the variations are asymptomatic and require no treatment,correct identification of these findings will reduce unnecessary further diagnostic assessments and will provide more appropriate treatment plans.

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La Articulación temporomandibular (ATM) cumple funciones importantes para la vida; su adecuado funcionamiento se puede alterar por trastornos temporomandibulares (TTM). La sintomatología de los TTM es variada, entre ellos se encuentra dolor en los músculos masticatorios, ruidos articulares y con menos frecuencia algunos pacientes refieren síntomas auditivos, lo que sugiere la existencia de una relación entre la ATM y el oído medio; sin embargo, esta relación no es clara. En consecuencia, el presente estudio tiene como propósito realizar una revisión de literatura para identificar los aspectos conocidos, desconocidos y controvertidos sobre la relación entre la ATM y el oído medio en niños y fetos. Se efectuó una búsqueda de la literatura en bases de datos utilizando los operadores booleanos (AND/OR) y los términos clave en inglés y en español. Se identificaron inicialmente 1080 artículos, se eliminaron los artículos duplicados y se aplicaron los criterios de inclusión y exclusión. Finalmente, se seleccionaron un total de 14 artículos que se revisaron a texto completo. Los estudios encontrados se enfocan en el desarrollo histoembriológico de la ATM y cómo ese desarrollo se da en conjunto con los componentes del oído medio. Adicionalmente, se identificaron investigaciones sobre el origen, la morfología y función del ligamento discomaleolar, el ligamento esfenomandibular y la fisura petrotimpánica como estructuras que conectan la ATM y el oído medio, pero los resultados han sido controvertidos. Se concluye que son necesarios más estudios para determinar cualquier relación anatómica y fisiológica que pueda existir entre la ATM y el sistema auditivo en fetos y niños.

SUMMARY: The temporomandibular joint (TMJ) has important functions for life; its proper functioning can be altered by temporomandibular disorders (TMD). The symptomatology of TMD is varied, including pain in the masticatory muscles, joint noises and less frequently some patients report auditory symptoms, suggesting the existence of a relationship between the TMJ and the middle ear; however, this relationship is not clear. Consequently, the present study aims to conduct a literature review to identify the known, unknown and controversial aspects of the relationship between TMJ and the middle ear in children and fetuses. A literature search was performed in databases using Boolean operators (AND/ OR) and key terms in English and Spanish. A total of 1080 articles were initially identified; duplicate articles were eliminated and inclusion and exclusion criteria were applied. Finally, a total of 14 articles were selected and reviewed in full text. The studies found focus on the histoembryological development of the TMJ and how that development occurs in conjunction with the middle ear components. Additionally, research on the origin, morphology, and function of the discomalleolar ligament, sphenomandibular ligament, and petrotympanic fissure as structures connecting the TMJ and middle ear was identified, but the results have been controversial. It is concluded that further studies are necessary to determine any anatomical and physiological relationship that may exist between the TMJ and the auditory system in fetuses and children.

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OBJECTIVE: Aim: To analyze morphometric changes in the structure of bone tissue of the mandibular articular processes and establish their densitometric dependence on the masticatory teeth loss in people of I-II periods of adulthood. PATIENTS AND METHODS: Materials and methods: We analyzed 136 digital CT recordings of human temporomandibular joints. The research subjects were divided into three groups based on the degree of dentition defect acquisition: the first - a limited defect, the second - a final defect, and the third - a preserved dentition (control); by age into two periods of adulthood of postnatal human ontogenesis. Digital statistical analysis of the bone density is presented as M±σ (mean and standard deviation). We compared the experimental groups with the control group using nonparametric statistical analysis. RESULTS: Results: Changes in the vertical dimension of occlusion due to limited masticatory teeth loss acquire variable morphometric features, causing an interrelated process of bone atrophy of the cellular part and the trabecular layer of the mandibular processes. The density of bone tissue of the cortical layer of the articular-fossa quadrant (A-Fh/q) of the articular head of the mandibular process increases on the right with limited defects and decreases with final defects. Indicators of bone densitometry of A-Fh/q on the left is characterized by a decrease with limited defects for individuals of the I-st period of adulthood and an increase in the final defects in the II-nd on the left and right. CONCLUSION: Conclusions: Multifactorial pathomorphological compensatory processes ensure bone density, but with a change in values on the right and a decrease on the left. Morphometric values of trabecular layers, the most vulnerable areas of the neck and base of the mandibular articular processes, indicate the reconstruc¬tion of their bone tissue with limited defects; in the first period of the adulthood, they decrease with a significant predominance on the left.

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SUMMARY: The aim of this systematic review was to assess the histological effects of platelet-rich plasma (PRP) on temporomandibular joint osteoarthritis (TMJ-OA) in animal models. A systematic search was performed using PubMed, WoS, EMBASE, Science Direct and SCOPUS databases. The inclusion criteria were experimental studies in animal models that evaluated the use of PRP as a treatment for TMJ-OA with or without arthrocentesis/arthroscopy. Comparison was made to a healthy control group or to other treatment. The variables evaluated were the histological effects of the treatments, characteristics of the primary articles, characteristics of the sample studied and the risk of bias. The systematic search identified 120 studies. Eventually 5 studies were included in the analysis. Four of the studies showed a statistically significant repair in joint tissues and improvement of cartilage thickness in animals treated with PRP. The global risk of bias was unclear. The results of this systematic review suggest that PRP treatment in TMJ-OA has benefits at the histological level in cartilage, articular disc and articular bone tissue in animal models. However, due to the low number of studies and the risk of bias, further research is needed to recommend its use.

El objetivo de esta revisión sistemática fue evaluar los efectos histológicos del plasma rico en plaquetas (PRP) en la osteoartritis de la articulación temporomandibular (ATM-OA) en modelos animales. Se realizó una búsqueda sistemática en las bases de datos PubMed, WoS, EMBASE, Science Direct y SCOPUS. Los criterios de inclusión fueron estudios experimentales en modelos animales que evaluaran el uso de PRP como tratamiento para la ATM-OA con o sin artrocentesis/ artroscopia. La comparación se realizó con un grupo de control sano o con otro tratamiento. Las variables evaluadas fueron los efectos histológicos de los tratamientos, las características de los artículos primarios, las características de la muestra estudiada y el riesgo de sesgo. La búsqueda sistemática identificó 120 estudios. Finalmente se incluyeron 5 estudios en el análisis. Cuatro de los estudios mostraron una reparación estadísticamente significativa en los tejidos articulares y una mejora del grosor del cartílago en los animales tratados con PRP. El riesgo global de sesgo fue incierto. Los resultados de esta revisión sistemática sugieren que el tratamiento con PRP en la ATM-OA tiene beneficios a nivel histológico en el cartílago, el disco articular y el tejido óseo articular en modelos animales. Sin embargo, debido al escaso número de estudios y al riesgo de sesgo, se necesitan investigaciones adicionales para recomendar su uso.

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Juvenile idiopathic arthritis (JIA) is a broad term that describes a group of heterogeneous rheumatologic diseases, mainly characterized by inflammation in the joints of children and young people up to 16 years of age. Its etiology is still not well understood and the diagnosis, essentially clinical, begins with the exclusion of other joint diseases. When the disease affects the temporomandibular joint, diagnosis is a challenge, as many patients are asymptomatic. The objective of this paper is to present a case of JIA with severe involvement of the temporomandibular joint and to discuss the clinical, radiographic, laboratory findings and the importance of early diagnosis. The lack of diagnosis of active arthritis in the temporomandibular joint in patients with JIA can cause irreversible effects such as micrognathia, malocclusion and reduced maximum mouth opening. Early diagnosis of temporomandibular joint involvement in JIA is important and needs to be investigated early in the clinical manifestation of systemic disease. Laboratory tests and clinical history are important to define treatment and prognosis, but not to predict temporomandibular joint arthritis. Imaging exams are important diagnostic tools to identify morphological changes in soft and hard tissues of the temporomandibular joint.

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OBJECTIVE: The objective of the study was to assess the differences in dentoskeletal morphology in males with and without temporomandibular joint osteoarthrosis (TMJOA). METHODS: Three hundred seventy-one male participants seeking orthodontic treatment were enrolled in this cross-sectional study. Each participant's osseous status was evaluated using cone-beam computed tomography (CBCT) and classified into normal (N = 104), indeterminate for TMJOA (N = 110) and TMJOA (N = 157) groups. The dentoskeletal characteristics were evaluated using cephalograms. Stratified analysis was performed based on age and skeletal pattern. Descriptive statistics and one-way analysis of variance were performed to investigate dentoskeletal differences among groups. P < .05 was considered statistically significant. RESULTS: The differences in posterior cranial base length, FMA, MP-OP, anterior facial height, articular angle, ramus height and L1-MP were statistically significant. After stratification by age, the differences in FMA, maxillomandibular angle, posterior facial height, facial height ratio, gonial angle and mandibular body length were statistically significant in adults. No statistical difference except for articular angle was observed in adolescents. After stratification by skeletal pattern, statistical differences were mainly apparent in skeletal Class II adults. CONCLUSION: Males with TMJOA showed a posteriorly positioned and backward-rotated mandible, especially in skeletal Class II adults. Compared with women, the craniofacial morphology of men is less affected by TMJOA. The association between TMJOA and craniofacial morphology also varied across different age groups and skeletal patterns. Prospective studies are required to clarify the cause-effect relationship between TMJOA and craniofacial morphology in males.

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Aim: This study aimed to evaluate the relationship between clinical findings and some factors such as age, gender, and remaining teeth on the anatomy of the temporomandibular joint in order to diagnose normal variations from abnormal cases. Methods: In this cross-sectional study, cone-beam computed tomography (CBCT) images of 144 patients referring to Tabriz Dental School for various reasons were selected and evaluated. The different aspects of the clinical parameters and the morphology of the condyle were evaluated on coronal, axial, and sagittal views. The CBCT prepared using the axial cross-sections had been 0.5 mm in thickness. The sagittal cross-sections had been evaluated perpendicular to the lengthy axis of the condyle at a thickness of 1 mm and the coronal cross-sections had been evaluated parallel to the lengthy axis of the condyle at a thickness of 1 mm. Data were analyzed with descriptive statistical methods and t-test, chi-squared test, using SPSS 20. The significance level of the study was p < 0.05. Results: There was a significant relationship between the condyle morphology, number of the teeth, and mastication side (p = 0.040). There were significant relationships between the condyle morphology, age between 20-40, and occlusion class I on the all the three views (coronal, axial, sagittal) (p = 0.04), (p = 0.006), (p = 0.006). Also, significant relationships were found in the condyle morphology and location of pain according to age, the number of remaining teeth, and gender. (p = 0.046) (p = 0.027) (p = 0.035). Conclusion:There are significant relationships between the clinical symptoms and condyle morphology based on age, gender, and the number of remaining teeth. The clinical finding that has the most significant relationship between the condyle morphology, remaining teeth (9-16 teeth), all of the age range (20-80 year), and gender was mastication side

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Oral behavior encompasses active movement of the oral structures. The range and quality of oral behavior is essential for establishing and maintaining health and well-being. Key oral behaviors include breathing, chewing, swallowing, and speech. Key hard tissue elements involved in oral behavior include the mandible, temporomandibular joints, and dentition. This article will discuss the anatomy and interaction of the hard tissue elements and selected soft tissue elements associated with oral behavior.

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BACKGROUND: The preferred masticatory side was reported to be almost always the same as the affected side of the temporomandibular disorder. Unbalanced alterations of temporomandibular joint morphology were found to be associated with unilaterally masticatory habits. The aim of this study was to investigate the effect of the mandibular movement on the remodeling of temporomandibular joint during eating French fries using a 3D motion capture system. METHODS: Twelve volunteers with non-maxillofacial deformity and a healthy temporomandibular joint were recruited. The 3D models of the mandible and the maxilla were reconstructed according to computed tomography. The subjects were asked to eat French fries by unilaterally mastication, which was recorded by a 3D motion capture system. The trajectories of the incisors and the condyles and the condylar acceleration during unilateral mastication were analyzed. RESULTS: During incisal biting, there was no significant difference in the condylar trajectories between the left and right sides (P > 0.05). During unilateral mastication, the average displacement and acceleration of the masticatory condyles were significantly lower than those of the non-masticatory condyles (P < 0.05). The trajectory angles of the masticatory condyles were significantly steeper than those of the non-masticatory condyle (P < 0.05). During swallowing, there was no obvious movement of the mandible. CONCLUSIONS: Between both temporomandibular joints, unilateral mastication resulted in significant differences in the regions of the condylar movement within the articular fossa, and then caused different compressive regions of the temporomandibular joints. Thus, unilateral mastication might result in a significantly different pattern of temporomandibular joint remodeling between the two sides.

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BACKGROUND: The aging process in the temporomandibular joints (TMJs) is related, more or less, with degenerative processes. Despite the rich literature on morphology and anatomy and the functioning of the components of the TMJs, there is much less research studies on the anatomy and diseases of these joints on historical populations. The aim of the study was to analyse the frequency and intensity of morphological and dysfunctional changes within the TMJ. MATERIALS AND METHODS: The research material included skeleton material from three chronologically and geographically diverse archaeological series located in Poland in the cities: Strzelce Krajenskie (n = 86), Santok (n = 86) and Wroclaw ('Kuronia' collection) (n = 70). The examination of the skeletal material was based on the macroscopic analysis of the articular surfaces of the TMJ. RESULTS AND CONCLUSIONS: The difference in the frequency of degenerative changes observed on the articular surfaces of the TMJs between the examined skeletal series from selected cities was insignificant (Santok: 81.4%, Strzelce Krajenskie: 72.1%, 'Kuronia': 68.6%). However, the obtained results showed a difference in the intensity of changes in the TMJ between individuals representing the early medieval population from Santok and individuals from the beginning of the 20th century collection 'Kuronia'.

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The temporomandibular joint is the direct interface between the mandible and the cranium and is critical for transmitting joint reaction forces and determining mandibular range of motion. As a consequence, understanding variation in the morphology of this joint and how it relates to other aspects of craniofacial form is important for better understanding masticatory function. Here, we present a detailed three-dimensional (3D) geometric morphometric analysis of the cranial component of this joint, the glenoid fossa, across a sample of 17 anthropoid primates, and we evaluate covariation between the glenoid and the cranium and mandible. We find high levels of intraspecific variation in glenoid shape that is likely linked to sexual dimorphism and joint remodeling, and we identify differences in mean glenoid shape across taxonomic groups and in relation to size. Analyses of covariation reveal strong relationships between glenoid shape and a variety of aspects of cranial and mandibular form. Our findings suggest that intraspecific variation in glenoid shape in primates could further be reflective of high levels of functional flexibility in the masticatory apparatus, as has also been suggested for primate jaw kinematics and muscle activation patterns. Conversely, interspecific differences likely reflect larger scale differences between species in body size and/or masticatory function. Results of the covariation analyses dovetail with those examining covariation in the cranium of canids and may be indicative of larger patterns across mammals.

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SUMMARY: The temporomandibular joint (TMJ) is the joint between the mandibular condyles, the mandibular fossa and the articular tubercle of the temporal bone. TMJ has been described as a "bicondylar" joint, a term that in current literature is used in multiple and dissimilar contexts. We present a scoping review of the term "bicondylar" as a descriptive term for TMJ in the scientific literature of the last 5 years. After selection according to the inclusion/exclusion criteria, 24 articles were selected for further analysis. The countries with the most publications were Brazil, India and Turkey with 3 articles each. Seven articles (29.17 %) were published by Spanish- speaking authors, six of these written in Spanish. Regarding the use of the term "bicondylar", 50 % of the articles referred to this term but did not explain it; 25 % cited this term to refer to the location in the left and right mandibular condyles; and 25 % the articles use the term and explain it according to the morphology of the articular surfaces. Discrepancies were also detected regarding as to how to consider TMJ: 54.17 % considered that TMJ is a single joint between a single bone (the jaw) and two bones of the cranium, while 45.83 % considered that TMJ are actually two different TMJs that work at the same time. We suggest discussing the appropriate use of the term "bicondylar" to avoid confusion and to be able to adapt and satisfy the needs of both anatomists and clinicians.

RESUMEN: La articulación temporomandibular (ATM) es la articulación entre los cóndilos mandibulares con la fosa mandibular y el tubérculo articular del hueso temporal. La ATM ha sido descrita como una articulación "bicondílea", término que en la literatura actual se utiliza en múltiples y disímiles contextos. Presentamos una revisión con búsqueda sistemática del término "bicondíleo" como término descriptivo de la ATM en la literatura científica de los últimos 5 años. Siguiendo criterios de inclusión/exclusión, se seleccionaron 24 artículos para su posterior análisis. Los países con más publicaciones fueron Brasil, India y Turquía con 3 artículos cada uno. Siete artículos (29,17 %) fueron publicados por autores de habla hispana, seis de ellos escritos en español. En cuanto al uso del término "bicondilar", el 50 % de los artículos se refieren a él, pero no lo explican; un 25 % citó este término para referirse a la ubicación en los cóndilos mandibulares izquierdo y derecho; y el 25 % de los artículos utilizan el término y lo explican según la morfología de las superficies articulares. También se detectaron discrepancias en cuanto a cómo considerar la ATM: el 54,17 % consideró que la ATM es una única articulación entre un solo hueso (la mandíbula) y dos huesos del cráneo, mientras que el 45,83 % consideró que la ATM son en realidad dos ATM diferentes que funcionan al mismo tiempo. Se sugiere discutir el uso adecuado del término "bicondilar" para evitar confusiones y poder adaptar y satisfacer las necesidades tanto de anatomistas como de clínicos.

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This study proposes a deep learning model for cortical bone segmentation in the mandibular condyle head using cone-beam computed tomography (CBCT) and an automated method for measuring cortical thickness with a color display based on the segmentation results. In total, 12,800 CBCT images from 25 normal subjects, manually labeled by an oral radiologist, served as the gold-standard. The segmentation model combined a modified U-Net and a convolutional neural network for target region classification. Model performance was evaluated using intersection over union (IoU) and the Hausdorff distance in comparison with the gold standard. The second automated model measured the cortical thickness based on a three-dimensional (3D) model rendered from the segmentation results and presented a color visualization of the measurements. The IoU and Hausdorff distance showed high accuracy (0.870 and 0.928 for marrow bone and 0.734 and 1.247 for cortical bone, respectively). A visual comparison of the 3D color maps showed a similar trend to the gold standard. This algorithm for automatic segmentation of the mandibular condyle head and visualization of the measured cortical thickness as a 3D-rendered model with a color map may contribute to the automated quantification of bone thickness changes of the temporomandibular joint complex on CBCT.

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Temporomandibular joint (TMJ) replacement with an implant is only used when all other conservative treatments fail. Despite the promising short-term results, the long-term implications of TMJ replacement in masticatory function are not fully understood. Previous human and animal studies have shown that perturbations to the normal masticatory function can lead to morphological and functional changes in the craniomaxillofacial system. A clearer understanding of the biomechanical implications of TMJ replacement in masticatory function may help identify design shortcomings that hinder their long-term success. In this study, patient-specific finite element models of the intact and implanted mandible were developed and simulated under four different biting tasks. In addition, the impact of re-attaching of the lateral pterygoid was also evaluated. The biomechanics of both models was compared regarding both mandibular displacements and principal strain patterns. The results show an excessive mediolateral and anteroposterior displacement of the TMJ implant compared to the intact joint in three biting tasks, namely incisor (INC), left moral (LML), and right molar (RML) biting. The main differences in principal strain distributions were found across the entire mandible, most notably from the symphysis to the ramus of the implanted side. Furthermore, the re-attachment of the lateral pterygoid seems to increase joint anteroposterior displacement in both INC, LML and RML biting while reducing it during LGF. Accordingly, any new TMJ implant design must consider stabilising both mediolateral and anteroposterior movement of the condyle during biting activities and promoting a more natural load transmission along the entire mandible.

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SUMMARY: One of the structures which contributes to the correct functioning of the Temporomandibular Joint (TMJ) is the Articular Disc (AD). Viewed in sagittal section, the AD is divided into four zones, the last is the Bilaminar Zone (BZ). The BZ is essential for keeping the AD in its superior position and for retracting the AD to posterior in the maximum aperture position. Its composition and the disposition of its components is unclear. The object of this narrative review is to update concepts on the anatomy of the BZ, with its variations, histological components, vascularization and innervation. The following databases were reviewed: PUBMED, SCOPUS, EMBASE, WEB OF SCIENCE, SciELO and LILACS. Only studies in human beings without alterations to the TMJ, using dissection in cadavers or radiography in live subjects, were included. Systematic reviews, letters to the editor, technical articles and experimental or quasi-experimental studies in animals were excluded. This review included a total of 24 articles which corresponded to the proposed research object. Our results describe the morphology of the BZ, its anatomical relations and possible variations, its histological components, types of fibre and distribution percentages; the latter are discussed in the literature, but no consensus exists. This is not the case for the vascularization and innervation of the BZ; all authors analyzed agree on these points, with just one author adding two possible arteries that may play a part in irrigation. Furthermore, a large number of authors recognize the discomalleolar ligament and its close relation with the BZ.

RESUMEN: Una de las estructuras que contribuye al correcto funcionamiento de la Articulación Temporomandibular (ATM) es el Disco Articular (DA). Visto en sección sagital, el DA se divide en cuatro zonas, la última de las cuales es la Zona Bilaminar (BZ). El BZ es esencial para mantener el AD en su posición superior y para retraer el AD hacia atrás en la posición de máxima apertura. Su composición y disposición de sus componentes no está clara. El objetivo de esta revisión es actualizar conceptos sobre la anatomía del BZ, además de sus variaciones, componentes histológicos, vascularización e inervación. Se revisaron las siguientes bases de datos: PUBMED, SCOPUS, EMBASE, WEB OF SCIENCE, SciELO y LILACS. Se incluyeron estudios en seres humanos sin alteraciones de la ATM, utilizando disección en cadáveres o radiografía en sujetos vivos. Se excluyeron las revisiones sistemáticas, cartas al editor, artículos técnicos y estudios experimentales o cuasi-experimentales en animales. Esta revisión incluyó un total de 24 artículos que correspondían al objeto de investigación propuesto. Nuestros resultados describen la morfología del BZ, sus relaciones anatómicas y posibles variaciones, sus componentes histológicos, tipos de fibras y porcentajes de distribución; estos últimos se discuten en la literatura, pero no existe consenso. Este no es el caso de la vascularización e inervación del BZ; todos los autores analizados coinciden en estos aspectos, y solo un autor agrega dos posibles arterias que pueden tener un papel en la irrigación. Además, un gran número de autores reconocen el ligamento disco maleolar y su estrecha relación con el BZ.

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