Exploring the Use of Animal Models in Craniofacial Regenerative Medicine: A Narrative Review.

The craniofacial region contains skin, bones, cartilage, the temporomandibular joint (TMJ), teeth, periodontal tissues, mucosa, salivary glands, muscles, nerves, and blood vessels. Applying tissue engineering therapeutically helps replace lost tissues after trauma or cancer. Despite recent advances, it remains essential to standardize and validate the most appropriate animal models to effectively translate preclinical data to clinical situations. Therefore, this review focused on applying various animal models in craniofacial tissue engineering and regeneration. This research was based on PubMed, Scopus, and Google Scholar data available until January 2023. This study included only English-language publications describing animal models' application in craniofacial tissue engineering (in vivo and review studies). Study selection was based on evaluating titles, abstracts, and full texts. The total number of initial studies was 6454. Following the screening process, 295 articles remained on the final list. Numerous in vivo studies have shown that small and large animal models can benefit clinical conditions by assessing the efficacy and safety of new therapeutic interventions, devices, and biomaterials in animals with similar diseases/defects to humans. Different species' anatomical, physiologic, and biological features must be considered in developing innovative, reproducible, and discriminative experimental models to select an appropriate animal model for a specific tissue defect. As a result, understanding the parallels between human and veterinary medicine can benefit both fields.

Actualización del análisis de los movimientos mandibulares a través de articulografía electromagnética / Updating the analysis of mandibular movements through electromagnetic articulography

El objetivo de registrar los movimientos mandibulares es obtener parámetros relevantes que permitan evaluar el estado de la articulación temporomandibular (ATM) y de los músculos involucrados en la masticación. El movimiento mandibular se debe a un conjunto complejo de rotaciones y traslaciones tridimensionales realizadas por la ATM, limitado por los ligamentos y las superficies articulares de estas, y por la morfología y la alineación de los dientes, cuando la mandíbula se desplaza sobre estos límites, se llaman movimientos bordeantes mandibulares. El objetivo de este artículo es realizar una descripción actualizada de los movimientos mandibulares a través de articulografía electromagnética. Los movimientos mandibulares bordeantes se clasifican según el plano del espacio en que se muevan, de esta manera tenemos movimientos bordeantes en el plano sagital, en el plano horizontal y el plano frontal, y en cada plano dibujan un polígono distinto, llamados polígonos de Posselt. Estos polígonos pueden ser registrados mediante Articulografía electromagnética, gracias a esta tecnología también se pueden extraer algunos parámetros interesantes, como por ejemplo: la trayectoria total recorrida por la mandíbula al describir cada polígono, rangos de desplazamiento en cada plano, área total de cada polígono de Posselt. La apertura mandibular se mide como la distancia entre los márgenes incisales de los incisivos centrales superiores e inferiores en apertura máxima más la sobremordida. El análisis de esta es una parte importante del examen clínico en odontología, ya que una apertura limitada puede ser resultado de trastornos en la articulación temporomandibular, fibrosis oral submucosa, enfermedad reumática o trauma facial. Las mediciones tridimensionales que se obtienen gracias a la Articulografía electromagnética, son apropiados para determinar los rangos normales de apertura, su exactitud permite la realización de investigaciones en el área, abriendo un amplio campo en el análisis de los movimientos mandibulares.

SUMMARY: The objective of recording mandibular movements is to obtain relevant parameters that allow the evaluation of the state of the temporomandibular joint (TMJ) and of the muscles involved in mastication. Mandibular movement is due to a complex set of three-dimensional rotations and translations performed by the TMJ, limited by the ligaments and their articular surfaces, and by the morphology and alignment of the teeth, when the mandible moves over these limits, they are called mandibular border movements. The aim of this article is to provide an updated description of mandibular movements through electromagnetic articulography. Mandibular border movements are classified according to the plane of space in which they move, thus we have border movements in the sagittal plane, in the horizontal plane and the frontal plane, and in each plane they draw a different polygon, called Posselt polygons. These polygons can be recorded by electromagnetic articulography, thanks to this technology some interesting parameters can also be extracted, such as: the total trajectory covered by the mandible when describing each polygon, displacement ranges in each plane, total area of each polygon of Posselt. Mandibular opening is measured as the distance between the incisal edges of the upper and lower central incisors at maximum opening plus the overbite. The analysis of mandibular opening is an important part of the clinical examination in dentistry as a preliminary evaluation, since limited opening can be the result of temporomandibular joint disorders, submucous oral fibrosis, rheumatic disease or facial trauma. The three-dimensional measurements that are obtained thanks to the electromagnetic Articulography, are appropriate to determine the normal ranges of opening, its accuracy allows the realization of investigations in the area, opening a wide field in the analysis of mandibular movements. Analysis of mandibular opening is an important part of the clinical examination in dentistry, since limited opening can be the result of temporomandibular joint disorders, oral submucous fibrosis, rheumatic disease, or facial trauma. Analysis of mandibular opening is an important part of the clinical examination in dentistry, since limited opening can be the result of temporomandibular joint disorders, oral submucous fibrosis, rheumatic disease, or facial trauma. The three-dimensional measurements that are obtained thanks to the electromagnetic Articulography, are appropriate to determine the normal ranges of opening, its accuracy allows the realization of investigations in the area, opening a wide field in the analysis of mandibular movements.

Orthognathic surgery effects on temporomandibular joint compressive stresses.

INTRODUCTION: This study tested orthognathic surgery effects on temporomandibular joint (TMJ) compressive stresses. METHODS: Pre- (T1) and post-surgery (T2) cone-beam computed tomography images were collected from consenting subjects aged ≥15 years. Anatomical data were used to measure surgical changes in anteroposterior mandibular position and occlusal plane angle (FH-OP), estimate condylar loading areas (mm2 ) and calculate T1 and T2 TMJ and jaw muscle forces (N) during canine biting via numerical modelling. Analysis of covariance tested for sex and biting angle differences in T2 - T1 TMJ compressive stresses (TMJ force/loading area, MPa). Principal component analyses identified jaw muscle forces that accounted for changes in T2 - T1 TMJ loads. Regression analyses tested the correlations between surgical changes in mandibular position, FH-OP, TMJ loads and muscle forces. RESULTS: Of 148 cases screened, 28 females and 16 males provided complete records. Condylar loading areas were significantly smaller (P = .024) for females vs males (124 ± 5 vs 144 ± 7 mm2 ). T2 - T1 differences in TMJ compressive stresses varied by surgical change, biting angle and sex. Overall, the largest increases in TMJ compressive stresses post-surgery were for females with mandibular setbacks where FH-OP angle decreased. T2 - T1 changes in jaw muscle forces had moderate (ipsilateral, λ = 4.59; η2 = 0.071) to large (contralateral, λ = 1.49; η2 = 0.31) effects on TMJ loads. CONCLUSIONS: T2 - T1 differences in TMJ compressive stresses during canine biting were affected by surgical changes in mandibular position and occlusal plane angle, biting angle and sex. Surgical changes altered jaw muscle forces for the same biting conditions and, thus, affected TMJ loads and compressive stresses.

The condylar capping for microvascular temporomandibular joint reconstruction: A preliminary study.

BACKGROUND: Defects of the temporomandibular joint (TMJ) are often difficult to be reconstructed in the correct dimensions and function. This preliminary study aims to describe a novel technique of condylar reconstruction with a microvascular flap in case of deforming arthrosis of the TMJ: condylar capping. PATIENTS AND METHODS: Four patients between 22 and 62 years old-three females and one male-with severe unilateral arthrosis of the TMJ underwent condylar capping. All patients had already had a failed conservative treatment, followed by arthroscopy with lysis and lavage and later open surgery with total or subtotal diskectomy combined with a condylar arthroplasty. Nevertheless, their pain was still at level six or more on a visual analogue scale. Moreover, they could eat only soft food. At this stage, they underwent condylar capping using an osteochondral lateral femoral condyle (LFC) flap. The surgical technique and the postoperative management are described in detail. Crucially the attachment of the lateral pterygoid muscle to the condylar neck was preserved in all cases. The patients were followed up clinically and by CT scan preoperatively, 6, and 12 months postoperatively. RESULTS: The mean height of the reconstructed neo-condyle was 6.0 mm, the mean width 16.2 mm, and the mean sagittal length 9.8 mm. The follow-up period ranged from 14 to 64 months. The procedures were uneventful for all patients, and the donor site morbidity was negligible. Twelve months later, the patients were all pain-free and able to have a regular diet. The TMJ and the knee had a normal range of movement and power. Postoperative imaging demonstrated bone healing and stable and anatomically correct condyle reconstruction. CONCLUSIONS: Based on the author's experience, the condylar capping with the LFC appears promising for reconstructing the condylar head in cases of severe osteoarthritis. Preserving the attachment of the lateral pterygoid muscle allows a complete restoration of the physiologic range of movement, including protrusion and laterotrusion of the mandible.

Lateral Pterygoid Muscle Ossification After Intraoral Condylectomy.

PURPOSE: Lateral pterygoid muscle ossification has not been reported in condylectomy patients. This study aimed to explore the incidence, risk factors, and imaging characteristics of 38 cases with lateral pterygoid muscle ossification among 54 patients after condylectomy via intraoral approach. METHODS: This retrospective study included 54 patients following simultaneous orthognathic surgery and condylectomy with coronoid process resection via intraoral approach. The authors evaluated the preoperative, 1 week, 6 months, and 1 year or more postoperative computed tomographic (CT) scans for the presence of lateral pterygoid muscle ossification and its characteristics. Sex, age at the time of surgery, disease course, affected side, preoperative alkaline phosphatase, pathology diagnosis, the height of the removed condyle, condylar shape, operator, preoperative temporomandibular joint movement, and clinical symptoms were assessed as risk factors for ossification. RESULTS: No incidence of lateral pterygoid muscle ossification was found on preoperative CT images. Various small-size osseous masses were observed in the lateral pterygoid muscles on postoperative 6 months CT images in 38/54 patients (70.37%) after condylectomy. But no apparent enlargement of the osseous masses was found. No patients complained of clinical discomfort or functional disorder during the follow-up period (23.11 ± 13.16 months). No significant risk factors for ossification were found. CONCLUSIONS: Lateral pterygoid muscle ossification is relatively common in patients after condylectomy via intraoral approach. However, its enlargement is self-limited and remains stable 6 months after surgery. it has no adverse effects on the temporomandibular joint functional movement.

EMG-assisted forward dynamics simulation of subject-specific mandible musculoskeletal system.

Assessment of mandibular dynamics is essential for examining stomatognathic functions, and many kinds of stomatognathic diseases, such as temporomandibular joint (TMJ) disorder and jaw tumors, require individual diagnosis and rehabilitation treatments. Musculoskeletal models of the mandible system provide an efficient tool for fulfilling these tasks, but most existing models are generic, without direct correlation to subject-specific data. For this reason, the objective of this study was to establish a subject-specific mandible modeling framework based on clinical measurements, including medical imaging, jaw kinematics, and electromyographic (EMG) acquisition. First, a non-rigid iterative closest point method was performed to register muscle insertion sites. A flexible multibody approach was introduced to describe the large deformation behavior of jaw muscles. The EMG signals of the temporalis and masseter muscles were then utilized to determine their active forces. Meanwhile, a feedback loop for tracking desired mandibular kinematics was presented to calculate the activations of jaw opening and pterygoid muscles. The subject-specific muscle forces and TMJ joint loading during jaw opening-closing movements were then calculated based on forward-inverse coupling dynamics procedure. As a validation of the proposed framework, the mandible trajectories of seven healthy subjects were predicted and compared with experimental data. The results demonstrated unintentional movement of the head-neck complex together with the activation patterns of jaw opening and lateral pterygoid muscles for different people. The proposed framework combines musculoskeletal modeling with dental biomechanical testing, providing an efficient method of predicting and understanding the dynamics of subject-specific mandible systems.

Modelo lineal vs. vectorial: estimación del movimiento mandibular y trabajo mecánico / Linear vs. vector model: estimation of mandible motion and mechanical work

Objetivo: Determinar los momentos de fuerza del haz superficial del masetero (SMH) obtenidos por modelos lineal y vectorial. Métodos: Investigación comparati-va in silico. Se obtuvo la fuerza del SMH con dinamó-metro en 12 pacientes varones adultos jóvenes para calcular el momento de la fuerza y trabajo mecánico a través de simulaciones en JAVA+ con NetBeans8.2. La descomposición de la fuerza fue F.cos α(x,y) y F.cos α(x,y,z) en el modelo lineal y vectorial respectivamen-te. Los momentos de fuerza fueron comparados por ANOVA (p<0,05). Resultados: La fuerza del SMH unila-teral obtenida con dinamómetro (2,5±0,1N) no difirió significativamente del modelo lineal (2,6±0,05N), pero difirió (p<0,001) del vectorial: 1,7, 2,2, 4,2N en x,y,z (general 2,7±0,02N). El momento medio de la fuerza en el modelo vectorial fue -17,9, -15,5, +14,3N.m-2, apuntando a la inclinación mandibular en el eje lateral en dirección caudal anterior, movimiento de inclina-ción en el eje lateral en la dirección cráneo-medial, e inclinación en el eje craneal en la dirección lateral-an-terior. El modelo lineal mostró momento de fuerza de 13,5N.m-2 apuntando un movimiento traslacional en dirección caudal-craneal en el eje anterior-posterior y menor trabajo mecánico del SMH (p=0,012). Con-clusión: Los modelos vectoriales son más eficientes proporcionando datos detallados para estimar los momentos de fuerza y el trabajo mecánico del SMH, y deben incluirse en los algoritmos de cálculo utilizados por dinamómetros (AU)

Objective: to determine the moments of force exerted by the superficial masseter head (SMH) obtained through linear models and vector ones. Methods: comparative in silico research. Data of SMH force obtained with dynamometer in 12 young adult male patients was used to calculate the moment of the force and mechanical work through simulations in JAVA+ performed with NetBeans8.2. Force decomposition was F.cos α(x,y) and F.cos α(x,y,z) in the linear and vector model respectively. The moments of force were compared by ANOVA (p<0.05). Results: Dynamometrical unilateral SMH force (2.5±0.1N) did not differ significantly from the linear model (2.6±0.05N), but differed (p<0.001) from the vector model: 1.7, 2.2, 4.2N on x,y,z (overall 2.7±0.02N). The mean moment of the force in the vector model was -17.9, -15.5, +14.3N.m-2, pointing to mandible's inclination on the lateral axis in anterior-caudal direction, inclination movement on the lateral axis in the cranio-medial direction and inclination on the cranial axis in the lateral-anterior direction. The linear model showed a moment of force of 13.5N.m-2 pointing to translational motion on caudal-cranial direction on the anterior-posterior axis and lower SMH mechanical work (p=0,012). Conclusion: Vector models are more efficient to provide detailed data to estimate the moments of force and mechanical work of SMH and should be included in the calculation algorithms used by dynamometers (AU)

Temporomandibular joint dysfunction following the use of a supraglottic airway device during general anaesthesia: a prospective observational study.

Supraglottic airway devices are commonly used to manage the airway during general anaesthesia. There are sporadic case reports of temporomandibular joint dysfunction and dislocation following supraglottic airway device use. We conducted a prospective observational study of adult patients undergoing elective surgery where a supraglottic airway device was used as the primary airway device. Pre-operatively, all participants were asked to complete a questionnaire involving 12 points adapted from the Temporomandibular Joint Scale and the Liverpool Oral Rehabilitation Questionnaire. Objective measurements included inter-incisor distance as well as forward and lateral jaw movements. The primary outcome was the inter-incisor distance, an accepted measure of temporomandibular joint mobility. Both the questionnaire and measurements were repeated in the postoperative period and we analysed data from 130 participants. Mean (SD) inter-incisor distance in the pre- and postoperative period was 46.5 (7.2) mm and 46.3 (7.5) mm, respectively (p = 0.521) with a difference (95%CI) of 0.2 (-0.5 to 0.9) mm. Mean (SD) forward jaw movement in the pre- and postoperative period was 3.6 (2.4) mm and 3.9 (2.4) mm, respectively (p = 0.018). Mean (SD) lateral jaw movement to the right in the pre- and postoperative period was 8.9 (4.1) mm and 9.1 (4.0) mm, respectively (p = 0.314). Mean (SD) lateral jaw movement to the left in the pre- and postoperative period was 8.8 (4.0) mm and 9.3 (3.6) mm, respectively (p = 0.008). The number of patients who reported jaw clicks or pops before opening their mouth as wide as possible was 28 (21.5%) vs. 12 (9.2%) in the pre- and postoperative period, respectively (p < 0.001) with a difference (95%CI) of 12.3% (6.7-17.9%). There was no significant difference in the responses to the other 11 questions or in the number of patients who reported pain in the temporomandibular joint area postoperatively. No clinically significant dysfunction of the temporomandibular joint following the use of supraglottic airway devices in the postoperative period was identified by either patient questionnaires or objective measurements.

Análisis morfológico y funcional del músculo pterigoideo lateral: una revisión de la literatura / Morphological and functional analysis of the lateral pterygoid muscle: a review of the literature

RESUMEN: El músculo pterigoideo lateral (MPL) es una estructura compleja y variable, poder determinar su anatomía exacta, relaciones vecinas, origen e inserciones, ayuda a los clínicos a comprender de mejor forma su función en el sistema estomatognático. En esta revisión se busca analizar la literatura que ayude a esclarecer la función antagónica de las cabezas del músculo pterigoideo lateral, desde un punto de vista nervioso, la descripción de su origen e inserciones y sus posibles variaciones anatómicas, además del análisis de sus funciones evaluado a través de la literatura tradicional y compararlo con lo descrito en artículos originales. Se analizaron diferentes bases de datos electrónicos y libros, con criterios de inclusión e exclusión claramente definidos, la lectura fue llevada a cabo por dos investigadores de manera independiente consultando de ser necesario con un tercer investigador. Esta revisión incluyo un total de 11 artículos y 4 libros atingentes a nuestro tema de estudio. Se expusieron los resultados a través de tablas de extracción de datos, que incluyó las funciones, inervación, el origen e inserción y las variaciones anatómicas del MPL. Nuestros resultados muestran que se identificaron claramente los elementos comunes de origen del MPL, pero su inserción mostró variaciones entre los distintos estudios, tanto en el porcentaje de fibras unidas como a los elementos anatómicos insertados. Considerando las funciones antagónicas de sus dos cabezas, autores lo han descrito como dos músculos diferentes, sin embargo desde un punto de vista nervioso, esta teoría no es apoyada. Finalmente comprender las funciones del MPL durante su acción es complejo, ya que la gran mayoría de los estudios disponibles utilizan cadáveres o electromiografía por lo que creemos que el desarrollo de metodologías menos invasivas y dolorosas, ayudarían a comprender el comportamiento de este músculo durante su función y como las variaciones anatómicas influyen en estas.

SUMMARY: 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.

Características anatómicas-funcionales que orientan la posición del cóndilo en la fosa mandibular en una relación céntrica: una descripción narrativa / Anatomical functional characteristics that guide the condylar position in mandibular fossa a centric relation: narrative description

RESUMEN: La Relación Céntrica (RC) es un concepto que busca definir la posición ideal del cóndilo de la mandíbula en la fosa mandibular, siendo esta posición muy discutida en la literatura y ha ido cambiado con los avances en conocimiento y tecnología. Tomándose en la actualidad en consideración elementos anatómicos esenciales que son utilizados como guía para el clínico. La importancia de poder reconocer esta posición radica en la correcta ejecución tanto de procedimientos diagnósticos como de tratamiento en diversas áreas de la odontología. Existen elementos anatómicos de la articulación temporomandibular (ATM) que nos ayudarían a comprender mejor el concepto de RC, entre estos destacan que la condensación ósea de las superficies articulares funcionales y su recubrimiento por fibrocartílago; la porción media del disco articular, desprovista de vasos y nervios; el techo de la fosa mandibular que puede llegar a ser extremadamente delgado por lo cual no se consideraría un área para soportar carga; la prolongación posterior del disco articular (DA) que es altamente vascularizada e inervada. El DA se encuentra íntimamente relacionado con estructuras como el ligamento temporomandibular o lateral y la cabeza superior del músculo pterigoideo lateral que permitirían junto a los elementos anteriormente mencionados el adecuado funcionamiento de la ATM. El correcto aprendizaje y utilización de estos conceptos contribuirá a lograr un mejor ejercicio del desarrollo profesional de estudiantes y profesionales del área de la odontología.

SUMMARY: 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.

Temporomandibular inflammation mobilizes parvalbumin and FosB/deltaFosB neurons of amygdala and dorsal raphe

Pathophysiological mechanisms involved in orofacial pain and their relationship with emotional disorders have emerged as an important research area for multidisciplinary studies. In particular, temporomandibular disorders (TMD) have been evaluated clinically from both physiological and psychological perspectives. We hypothesized that an altered neuronal activity occurs in the amygdala and the dorsal raphe nucleus (DR), encephalic regions involved in the modulation of painful and emotional information. Adult male Wistar rats were used in an experimental complete Freund's adjuvant (CFA)-induced temporomandibular joint (TMJ) inflammation model. CFA was applied for 1 or 10 days, and the animals were euthanized for brain samples dissection for FosB/ΔFosB and parvalbumin (PV) immunostaining. Our results were consistent in showing that the amygdala and DR were activated in the persistent inflammatory phase (10 days) and that the expression of PV+ interneurons in the amygdala was decreased. In contrast, in the DR, the expression of PV+ interneurons was increased in persistent states of CFA-induced TMJ inflammation. Moreover, at 10 days of inflammation, there was an increased co-localization of PV+ and FosB/ΔFosB+ neurons in the basolateral and central nucleus of the amygdala. Different nuclei of the amygdala, as well as portions of the DR, were activated in the persistent phase (10 days) of TMJ inflammation. In conclusion, altered activity of the amygdala and DR was detected during persistent inflammatory nociception in the temporomandibular joint. These regions may be essential for both sensory and affective dimensions of orofacial pain.

On the reinsertion of the lateral pterygoid tendon in total temporomandibular joint replacement surgery.

This report aims to present the concept of reestablishing lateral pterygoid muscle function during total temporomandibular joint (TMJ) replacement surgery. The key feature is a lattice structure (scaffold) located in the condylar neck of a titanium, three-dimensionally (3D)-printed mandibular component that houses morselized autologous bone from the resected condyle and osteogenic stem cells from iliac bone marrow aspirate, and to which the fibrous enthesis component (collagen attachments to a bone fragment) is fixed via suture cerclage prior to the development of the bony union. Five TMJs were replaced using enthesis reconstruction in three patients who were followed for 1 year and more. Laterotrusion to the contralateral side measured on average 6.4 mm preoperatively, 2.3 mm at 1 month, 3 mm at 3 months, 4 mm at 6 months, and at 1-1.5 years (62,5% of the preoperative laterotrusion/40% of a normal laterotrusion). Subjective normalization of mastication after 1 year was present in all patients. A successful reattachment of the enthesis to an alloplastic endoprosthesis suggests that patients will not only be able to open and close their mouths properly with reduced pain but will also be able to actually chew. The technique has potential applications in orthopedic alloplastic reconstruction.

[Dysfunction of the manducatory apparatus]. / Dysfonction de l'appareil manducateur.

Temporo-mandibular disorders -TMD- involve a whole set of anatomical, physiological and clinical disorders that exceed by far the sole temporo-mandibular joint. The main symptom of this condition, most frequent in female patients, is pain. Three syndromes are associated with TMD: a muscular syndrome, not only involving masticatory muscles but also muscles of the neck and pain in seemingly unrelated anatomical regions, which can be misleading; an inflammatory articular syndrome; a mechanical syndrome affecting mouth-opening path. The main treatment of this very common and benign disorder is based on physical therapy. However, physicians should be warned that some patients might exhibit similar symptoms in rare cases of malignant tumor.

DYSFONCTION DE L'APPAREIL MANDUCATEUR La notion de dysfonction de l'appareil manducateur doit être considérée selon un ensemble anatomoclinique et physiopathologique qui dépasse largement l'articulation temporomandibulaire. Cette symptomatologie essentiellement féminine et douloureuse s'exprime selon trois syndromes volontiers intriqués : un syndrome musculaire qui, au-delà des muscles de la mastication, peut intéresser la musculature cervicale et provoquer des douleurs dont le siège égare aisément le diagnostic ; un syndrome articulaire inflammatoire ; un syndrome mécanique qui altère le chemin d'ouverture de la mandibule. Le traitement est avant tout fonctionnel, s'appuyant sur la rééducation. Mais cette symptomatologie d'apparence et d'étiologie si banales ne doit pas laisser ignorer qu'elle peut avoir une cause plus sombre à type de tumeur maligne régionale.

The normal range of maximal incisal opening in pediatric population and its association with physical variables.

Background: Restricted mouth opening is a common complaint in patients suffering from temporomandibular joint disorders, ankylosis, impaired masticatory muscle function, rheumatic disease, infection, or malignancy. As with any disease, the aim of treatment of disorders affecting mouth opening is to restore the mouth opening to its normal value. It is thus of paramount importance to determine the normal value. Objective: To establish the normal range of maximal incisal opening (MIO) in children aged 4 to 15 years and to investigate the correlation between MIO and age, gender, height, and body weight. Materials and Methods: Six hundred and two children from various schools in Bengaluru, India, participated in the study. The children were divided into the following age groups: 4-5, 6-7, 8-9, 10-11, 12-13, and 14-15 years. MIO for the children was recorded using Therabite® scale. The measurements of MIO were then correlated with gender, body weight, and height of the children in different age groups. Results: It was observed that MIO gradually increased with age with a mean MIO of 41.34 mm at 4-5 years to a mean MIO of 51.73 mm at 14-15 years. The mean MIO value for males (48.90 ± 6.49 mm) was found to be higher when compared to that of females (46.17 ± 5.58 mm). The results indicated a strong positive correlation of MIO with height and weight. Conclusion: MIO gradually increased with age in both the genders, and a strong positive correlation of MIO with height and weight was observed.

RésuméContexte: L'ouverture restreinte de la bouche est une plainte fréquente chez les patients souffrant de troubles de l'articulation temporo-mandibulaire, d'ankylose, d'altération de la fonction musculaire masticatoire, de rhumatisme articulaire, d'infection ou de cancer. Comme pour toute maladie, le traitement des troubles de l'ouverture de la bouche a pour objectif de ramener cette ouverture à sa valeur normale. Il est donc primordial de déterminer la valeur normale. Objectif: Établir la plage normale d'ouverture maximale de l'incision (OMI) chez les enfants âgés de 4 à 15 ans et étudier la corrélation entre l'ouverture maximale de l'incision et l'âge, le sexe, la taille et le poids corporel. Conception de l'étude: Six cent deux sujets de diverses écoles de Bangalore, en Inde, ont participé à l'étude. Les sujets ont été répartis dans les groupes d'âge suivants: 4-5, 6-7, 8-9 ans, 10-11 ans, 12-13 ans et 14-15 ans. L'ouverture incisive maximale des sujets a été enregistrée avec l'échelle Therabite®. Les mesures de MIO ont ensuite été corrélées avec le sexe, le poids corporel et la taille des enfants dans différents groupes d'âge. Résultats: Il a été observé que le MIO augmentait progressivement avec l'âge, avec un MIO moyen de 41,34 mm à 4-5 ans, pour atteindre un MIO moyen de 51,73 mm à 14-15 ans. La valeur moyenne maximale de l'ouverture incisive chez les hommes (48,90 ± 6,49 mm) s'est avérée plus élevée que celle des femmes (46,17 ± 5,58 mm). Les résultats ont montré une forte corrélation positive entre le MIO et la taille et le poids. Conclusion: le MIO a augmenté progressivement avec l'âge chez les deux sexes et une forte corrélation positive entre le MIO et la taille et le poids a été observée.

Cranial Anchored Mandible Distraction Osteogenesis.

Multiple or large distance mandibular distraction osteogenesis (MDO) in the older child is often complicated by iatrogenic temporomandibular joint (TMJ) pathology. The transmission of significant force to the TMJ in these particular patients is due to the greater distance of distraction required and the relative inelasticity of the soft tissue envelope. The authors present a clinical report of a successful asymmetrically vectored large distance MDO in a 13-year-old female with bilateral craniofacial microsomia with Goldenhar syndrome. During distraction, the TMJ joints were effectively unloaded from the forces of distraction using external bilateral cranial anchored devices (Cranio-Mandibular Fixator; KLS Martin, Jacksonville, FL). Angle's occlusion, facial angle, and evidence of TMJ pathology were assessed.

Evaluation of Temporomandibular Joint Movement After Mandibular Reconstruction.

Mandibular head dislocation and problems with mouth opening may develop after mandibular reconstruction. The authors investigated dislocation of the mandibular head and amount of protrusive sliding (excursion) and their effect on mouth opening. The authors divided 55 mandibular reconstruction patients into 3 groups on the basis of the extent of masticatory muscle and mandibular resection and investigated mandibular head dislocation. On the other hand, the authors focused on mandibular head protrusive excursion as a function of a reconstructed mandible. Protrusive excursion was measured by plain radiography in 29 patients. The extent of mouth opening was measured between the central incisors. Fluoroscopy was performed in 9 patients and the motions of the mandible were analyzed with video-analysis software. Mandibular head dislocation was observed in 15 patients (27.2%) who underwent resection of the mandibular ramus and coronoid process. The extent of mouth opening did not vary significantly among the 3 groups but was lower than that in healthy persons. Mandibular excursion was restricted in patients with conserved temporalis and lateral pterygoid muscles. Protrusive excursion was correlated with the extent of mouth opening. Structural problems involving dislocation of the mandibular head are caused by severing the coronoid process and protrusive excursion disorders are important factors causing mouth opening problems. Physiological sliding and other motions were observed in reconstructed models. The authors believe that when the ramus is resected, there is a greater chance of articular head dislocation. These findings suggest that dislocation of the mandibular head and protrusive excursion disorders arise from imbalances of the remaining masticatory muscles.

Resorption behaviour of the articular surface dome and functional outcome after open reduction and internal fixation of mandibular condylar head fractures using small-fragment positional screws.

PURPOSE: The aim of the study was to evaluate the resorption of the mandibular condylar head after open reduction and internal fixation of fractures with small-fragment screws and to evaluate the functional outcome. PATIENTS AND METHOD: Forty-eight patients (55 condylar head fractures) underwent surgical treatment. All kinds of complications were recorded. In a subgroup of 20 patients, the average loss of bone height of the condylar head joint surface was gauged by measuring the vertical distances from 3 selected reference points of the fixation hardware to the vertex of the condyle in views of multiplanar radiographs after 6 months. Functional outcome was analysed by Helkimo index score. RESULTS: Complication rates were low. Osteosynthesis loosening occurred in 4 cases. The mean bone resorption along the condylar head joint surface in the subgroup of 20 patients (with 23 joints) was 0.7 mm. Functional outcome was rated as follows: 8 patients - good, 11 patients - slightly impaired, 1 patient - moderately impaired. CONCLUSION: Open reduction and internal fixation of condylar head fractures with small-fragment screws leads to reliable results in terms of joint surfaces relatively resistant to resorption and function. Low bone resorption on the joint surface of the condylar head can be expected.

The influence of bilateral sagittal split ramus osteotomy on the stress distributions in the temporomandibular joints of the patients with facial asymmetry under symmetric occlusions.

The aim of this study is to compare the differences in the stress distributions in the temporomandibular joints (TMJs) of the patients with facial asymmetry before and after bilateral sagittal split ramus osteotomy (BSSRO) under the symmetric occlusions using the three-dimensional (3D) finite element method.Ten facial asymmetry patients (Preoperative group, age 24.6 ±â€Š4.8 years) and 10 asymptomatic subjects (Control group, age 26.8 ±â€Š4.9 years) were recruited. After the patients underwent BSSRO, they were further assigned as the Postoperative group. 3D geometries of the finite element models of the mandible, disc, maxilla, and teeth were reconstructed according to cone-beam computed tomography (CBCT) image data. Contact elements were used to simulate the interaction of the disc-condyle, disc-temporal bone, and upper-lower dentition. The muscle forces and boundary conditions corresponding to the central and anterior occlusions were applied on the models of the 3 groups. The finite element models were validated with experimental data showing the accuracy of the simulation results.The simulation predicted preoperative significant differences of stresses between non-deviated sides and deviated sides were disappeared after the surgery under the central and anterior occlusions (P < .05). Almost all stresses in the patient models had significantly decreased after BSSRO, leveling it to the stress values of the normal subjects. Moreover, the simulation results coincided with the clinical cases which showed that BSSRO had helped to release or remove the signs and symptoms of temporomandibular disorders (TMD).In conclusion, BSSRO could correct the asymmetric stress distributions of TMJs and decrease the magnitude of the stresses for the patients with facial asymmetry. Those decreases also associated with the recovery of TMD.

Temporomandibular joint regeneration: proposal of a novel treatment for condylar resorption after orthognathic surgery using transplantation of autologous nasal septum chondrocytes, and the first human case report.

BACKGROUND: Upon orthognathic mandibular advancement surgery the adjacent soft tissues can displace the distal bone segment and increase the load on the temporomandibular joint causing loss of its integrity. Remodeling of the condyle and temporal fossa with destruction of condylar cartilage and subchondral bone leads to postsurgical condylar resorption, with arthralgia and functional limitations. Patients with severe lesions are refractory to conservative treatments, leading to more invasive therapies that range from simple arthrocentesis to open surgery and prosthesis. Although aggressive and with a high risk for the patient, surgical invasive treatments are not always efficient in managing the degenerative lesions. METHODS: We propose a regenerative medicine approach using in-vitro expanded autologous cells from nasal septum applied to the first proof-of-concept patient. After the required quality controls, the cells were injected into each joint by arthrocentesis. Results were monitored by functional assays and image analysis using computed tomography. RESULTS: The cell injection fully reverted the condylar resorption, leading to functional and structural regeneration after 6 months. Computed tomography images showed new cortical bone formation filling the former cavity space, and a partial recovery of condylar and temporal bones. The superposition of the condyle models showed the regeneration of the bone defect, reconstructing the condyle original form. CONCLUSIONS: We propose a new treatment of condylar resorption subsequent to orthognathic surgery, presently treated only by alloplastic total joint replacement. We propose an intra-articular injection of autologous in-vitro expanded cells from the nasal septum. The proof-of-concept treatment of a selected patient that had no alternative therapeutic proposal has given promising results, reaching full regeneration of both the condylar cartilage and bone at 6 months after the therapy, which was fully maintained after 1 year. This first case is being followed by inclusion of new patients with a similar pathological profile to complete an ongoing stage I/II study. TRIAL REGISTRATION: This clinical trial is approved by the National Commission of Ethics in Medical Research (CONEP), Brazil, CAAE 12484813.0.0000.5245, and retrospectively registered in the Brazilian National Clinical Trials Registry and in the USA Clinical Trials Registry under the Universal Trial Number (UTN) U1111-1194-6997 .