A surgical management of articular disc injury in temporomandibular Joint: A compiled case series of two cases with articular disc tear managed with surgical intervention

Articular disc injury in the temporomandibular joint (TMJ) can lead to significant pain and limited jaw movement. We present two cases in this case series of articular disc injuries in the TMJ and elaborate on their etiology, clinical presentation, diagnostic modalities, and treatment provided with follow-up reviews. Case 1 involved a 50-year-old female with a history of pain and clicking in the left TMJ for 10 years, wherein imaging studies revealed a discal tear. Case 2 involved a patient who presented with trauma and was diagnosed with a displaced disc with a disc tear when the patient was screened for mandibular fractures. The patients underwent surgical intervention, and the disc tear was repaired, following which both showed marked improvement. Our cases highlight the importance of early diagnosis and necessary surgical management of articular disc injury in the TMJ for better clinical outcomes.

Articulación temporomandibular ¿disco o menisco articular? / Temporomandibular joint, disc or articular meniscus

Los términos disco y menisco se encuentran en Terminologia Anatomica. Sin embargo, ambos términos son utilizados como sinónimos para referirse al cartílago intraarticular presente en la articulación temporomandibular (ATM). Por este motivo, el objetivo de este estudio es exponer las raíces griegas de los términos disco y menisco para evaluar la coherencia entre su relación léxica y su relación morfológica. Ambos términos fueron consultados en el Programa Federativo Internacional de Terminología Anatómica y en diccionarios de idiomas griego, español e inglés. La búsqueda reportó que el término "disco" deriva del latín discus, y este a su vez del griego δίσκος [dískos] que significa "cuerpo cilíndrico cuya base es muy grande respecto a su altura". Por su parte "menisco" proviene del griego mēnískos μηνίσκος [mḗn μήν gr. μείς 'meis', 'luna creciente' + -iskos gr. Sufijo diminutivo 'pequeño'] que significa "luna creciente pequeña" y se define como "cartílago de forma semilunar y de espesor menguante de la periferia al centro; forma parte de la articulación de la rodilla". Por lo tanto, la definición anatómica de disco articular y menisco está determinada por su morfología según la etimología de la palabra. En la ATM se encuentra un disco articular entre los huesos articulares, según su morfología.

SUMMARY: The terms disc and meniscus are found in Terminologia Anatomica. However, both terms are used synonymously to refer to the intra-articular cartilage present in the temporomandibular joint (TMJ). For this reason, this study aims to expose the greek roots of the terms disc and meniscus to evaluate the coherence between their lexical and morphological relationships. Both terms were consulted in the International Federative Program of Anatomical Terminology and in Greek, Spanish and, English dictionaries. The search reported that the term "disc" derives from the Latin discus, and this in turn from the Greek δίσκος [dískos], which means "cylindrical body whose base is very large compared to its height". For its part, "meniscus" comes from the Greek mēnískos μηνίσκος [mḗn μήν gr. μείς 'meis', 'crescent moon' + -iskos Gr. Diminutive suffix 'small'] which means "small crescent moon" and, is defined as "cartilage with a semilunar shape and decreasing thickness from the periphery to the center; It is part of the knee joint. Therefore, the anatomical definition of articular disc and meniscus is determined by its morphology according to the etymology of the word. In the TMJ, an articular disc is found between the articular bones, depending on their morphology.

Application of modified articular disc anchorage in treating the perforation and rupture of temporomandibular joint disc / 华西口腔医学杂志

OBJECTIVES@#This study aimed to use modified articular disc anchorage in treating old irreducible temporomandibular joint (TMJ) disc displacement with perforation and rupture, as well as to explore its efficacy.@*METHODS@#A total of 31 patients (34 sides) with 47 TMJ disc perforations who underwent surgical treatment in the Affiliated Stomatolo-gical Hospital of Nanchang University from January 2018 to December 2021 were selected. According to the location of disc perforation, it has five types: posterior disc perforation (typeⅠ), anterior disc perforation (typeⅡ), lateral disc perforation (type Ⅲ), composite disc perforation, and destruction disc perforation. The modified methods of disc anchoring were divided into two types according to the location of the perforation. TypesⅠandⅢ disc perforation were trea-ted by posterior anchoring method. For posterior ancho-ring, a screw was implanted into the posterolateral side of the condylar neck, and the disc was fixed on the screw by horizontal mattress suture. TypeⅡdisc perforation and compo-site disc perforation combined typeⅡperforation were treated by anterior and posterior double-anchoring method. For anterior anchoring, anchor screws or holes were placed at the anterior edge of the condylar neck, and horizontal mattress suture was performed at the posterior edge of the anterior perforation with an anchor wire. The articular disc was then fixed on the anchor screws or holes. For the posterior anchoring method, it was the same as the previous one. Paired t test was used to analyze the visual analog scale (VAS), maximum interincisal opening (MIO), and TMJ disorder index (CMI) of the patient before surgery and 1, 3, and 6 months after surgery. Disk-condyle position relationship by magnetic resonance imaging and postoperative quality of life in postoperative were analyzed.@*RESULTS@#The incidence of perforation was 41.2% (14/34) in typeⅠ, 11.8% (4/34) in typeⅡ, 8.8% (3/34) in typeⅢ, 29.4% (10/34) in composite type, and 8.8% (3/34) in destruction type. The VAS, MIO, and CMI at 3, 6 months after operation significantly improved compared with those before operation (P<0.05). The effective reduction rate of disc was 96.77% (30/31). The quality of life at 6 months after surgery was 47.22±2.13, and the rate of excellent evaluation was 96.4% (27/28).@*CONCLUSIONS@#Modified articular disc anchorage achieves a good curative effect for treating temporomandibular joint disc perforation and rupture. Nevertheless, its long-term effect requires further observation.

Quality Evaluation of Temporomandibular Joint Images from 3 High-resolution Dynamic Sequences / 中国医学科学院学报

Objective To compare the image quality of three high-resolution dynamic MRI methods for evaluating the motion of temporomandibular joint disc and condyle. Methods Twenty-five patients with suspected temporomandibular joint disorders were examined by single-shot fast spin-echo (SSFSE),fast imaging employing steady-state acquisition (FIESTA),and spoiled gradient echo (SPGR) on the oblique sagittal position.Two radiologists performed subjective and objective evaluation on the images with double-blind method.The subjective evaluation included the signal intensity of mandibular condyle,articular disc,soft tissue around articular disc,and lateral pterygoid muscle,the contrast between articular disc and condyle,the contrast between articular disc and surrounding soft tissue,condylar motion,and disc movement.The objective evaluation indexes included image signal intensity,signal-to-noise ratio (SNR),and contrast-to-noise ratio (CNR).The subjective and objective indexes of the image quality were compared between the three sequences. Results The SSFSE sequence had lower signal intensity of articular disc and higher signal intensity of condyle and surrounding soft tissue than FIESTA and SPGR sequences (all P<0.001).The SPGR sequence showed higher signal intensity of lateral pterygoid muscle than the SSFSE and FIESTA sequences (P=0.017,P<0.001).Among the three sequences,SSFSE sequence showed the clearest articular disc structure (χ2=41.952,P<0.001),the strongest contrast between articular disc and condyle (χ2=35.379,P<0.001),the strongest contrast between articular disc and surrounding soft tissue (χ2=27.324,P<0.001),and the clearest movement of articular disc (χ2=44.655,P<0.001).SSFSE and FIESTA sequences showed higher proportion of disc displacement and reduction than SPGR sequence (all P<0.001).The CNR (χ2=21.400,P<0.001),SNR (χ2=34.880,P<0.001),and condyle signal intensity (F=337.151,P<0.001) demonstrated differences among SSFSE,FIESTA,and SPGR sequences.The CNR of SSFSE sequence was higher than that of FIESTA sequence (P<0.001),while it had no significant difference between SSFSE and SPGR sequences (P=0.472).In addition,the SSFSE sequence had higher SNR and signal intensity than FIESTA and SPGR sequences (all P<0.001). Conclusion The best image quality can be observed from SSFSE sequence where both the structure and movement of temporomandibular joint are well displayed.Therefore,SSFSE is preferred for the examination of temporomandibular joint movement.

Discrepancia estructural del disco y cápsula articular de la ATM en resonancia nuclear magnética. Revisión de la literatura / Structural discrepancy of the disc and articular capsule of the TMJ on magnetic resonance imaging. Literature review

RESUMEN La articulación temporomandibular (ATM) es considerada una articulación del tipo diartrosis bicondílea. La evaluación imagenológica comprende una parte fundamental en su evaluación, la que debe abarcar tanto las características óseas como los tejidos blandos y la relación entre ellos. La resonancia nuclear magnética (RNM) representa el gold standard para el estudio de tejidos blandos, sin embargo, hasta ahora su mayor aplicación continúa siendo la visualización del disco articular. Es por esto, que el presente artículo tuvo como objetivo señalar la información disponible en la literatura con respecto a la visualización de la cápsula articular en RNM y evaluarla como una estructura independiente.

SUMMARY The temporomandibular joint (TMJ) is considered a bicondylar diarthrosis joint. Imaging evaluation comprises a fundamental part of its evaluation, which must include both bone characteristics as well as soft tissues and the relationship between them. Magnetic resonance imaging (MRI) represents the gold standard for the study of soft tissues, however, until now its greatest application continues to be the visualization of the articular disc. This is why the present article aimed to point out the available information in the literature regarding the visualization of the joint capsule in MRI as an independent structure.

Temporomandibular joint arthrocentesis: a technique proposal. Case report / Artrocentese da articulação temporomandibular: uma proposta de técnica. Relato de caso

ABSTRACT BACKGROUND AND OBJECTIVES: Arthrocentesis is an effective treatment to reduce or eliminate pain, increase maximal interincisal distance, and to eliminate joint effusion in patients with disc displacement without reduction. This study aims to expose and to discuss a new technique proposal of temporomandibular joint arthrocentesis applied in the treatment of a single case of disc displacement without reduction. CASE REPORT: Female patient, 18-year-old patient sought treatment due to joint pain and mouth opening limitation. The maximal interincisal distance was 30.28mm. Magnetic resonance imaging confirmed the diagnosis of disc displacement without reduction with signs of joint effusion in the right temporomandibular joint. Temporomandibular joint arthrocentesis was performed under selective sensory nerve block of the auriculotemporal, the masseteric and posterior deep temporal nerves. Two needles were inserted in the upper compartment of the temporomandibular joint. In the second needle, a transparent catheter was connected into a vacuum pump. Clinically, after the arthrocentesis, the maximal interincisal distance increased to 46.25mm, and the patient referred no more pain. After six months, a magnetic resonance imaging was performed to observe the results, and there were no more signs of joint effusion. CONCLUSION: Temporomandibular joint arthrocentesis was an effective treatment for this patient with disc displacement without reduction. The aspect of this technique that is particularly relevant for clinical practice was the connection of a transparent catheter to a vacuum pump. In fact, it allowed the visualization of the solution fluidity, as well as guides the flow of the solution used for joint washing, optimizing the irrigation. However, new studies are necessary to compare different protocols of irrigation with and without the associated use of a vacuum pump.

RESUMO JUSTIFICATIVA E OBJETIVOS : A artrocentese e um tratamento eficaz para diminuir ou abolir a dor, aumentar a máxima distância interincisal e eliminar o derrame articular em pacientes com deslocamento de disco sem redução. O objetivo deste estudo foi expor e discutir uma nova proposta técnica de artrocentese da articulação temporomandibular aplicada no tratamento de um caso de deslocamento de disco sem redução. RELATO DO CASO : Paciente do sexo feminino, 18 anos procurou tratamento devido a dor na articulação temporomandibular e limitação da abertura da boca. A distância interincisal máxima foi de 30,28mm. A ressonância magnética confirmou o diagnóstico de deslocamento de disco sem redução com sinais de derrame articular na articulação temporomandibular direita. A artrocentese foi realizada com o bloqueio anestésico do nervo auriculotemporal, masseterino e temporal profundo posterior. Depois disso, duas agulhas foram inseridas no compartimento superior da articulação temporomandibular. Na segunda agulha foi conectado um cateter transparente e nesse uma bomba de vácuo. Clinicamente, após a artrocentese, a distância interincisal máxima aumentou para 46,25mm e não houve mais dor. Na nova ressonância magnética realizada 180 dias após, não havia mais sinais de derrame articular. CONCLUSÃO : A artrocentese da articulação temporomandibular foi eficaz no tratamento do paciente com deslocamento do disco sem redução. O aspecto dessa técnica, que é particularmente relevante para a prática clínica, foi a conexão de um cateter transparente a uma bomba de vácuo. Isso permitiu a visão da solução, sua fluidez, além de orientar o fluxo da solução utilizada para lavagem, otimizando a irrigação. No entanto, novos estudos são necessários para comparar diferentes protocolos de irrigação com e sem o uso associado de uma bomba de vácuo.

Surgical treatment of chronic prolonged mandibular dislocation: case report and literature review / 口腔疾病防治

Objective@#To investigate the treatment methods of chronic prolonged mandibular dislocation.@*Methods@#Surgical reduction was performed in a case of temporomandibular joint dislocation over 6 months after manual reduction failure. The flap was removed under general anesthesia, and the bone of the condyle were removed. The articular disc was aligned and incision was sutured, and the procedure was combined with intermaxillary fixation for a correct occlusion and traction. After the operation, the surgical efficacy was observed, and the related literature was reviewed. @*Results@#The patient recovered well after the operation; the mouth opening was 3 cm, and the occlusion was normal. No recurrence was observed after 10 months of follow-up. The literature shows that surgery is a common treatment for temporomandibular joint dislocation after the failure of manual reduction, and postoperative patient education can reduce recurrence and complications. @*Conclusion @#Surgery combined with intermaxillary traction can effectively treat chronic prolonged mandibular dislocation.

Clinical study of treating anterior disk displacement without reduction by conservative sequence method / 实用口腔医学杂志

Objective:To observe the clinical effects of conservative sequence method in the treatment of anterior disk displacement without reduction(ADDWR).Methods:300 patients with ADDWR were included.200 patients were treated by conservative sequence method (including upper articular cavity lavage with single needle + injection of sodium hyaluronate gel + physical therapy + gimmick reset + oral exercise) (group 1);the other 100 were treated by injection of sodium hyaluronate gel(group 2).Maximum mouth opening (MM0) and pain visual analogue scale(VAS) were measured and compared before and after treatment.Results:In group 1 the effective rate was 95.5％,before treatment MMO was (22.90 ± 3.18) mm,VAS (5.81 ± 0.32);3 months after treatment MMO (37.05 ± 4.43) mm,VAS (1.29 ± 0.19);6 months after treatment MMO (36.29 ± 4.08) mm,VAS (1.37 ± 0.22);12 months after treatment MMO (35.76 ±3.87) mm,VAS (1.52 ±0.28),respectively.In group 2,the effective rate was 78％,before treatment MMO was(23.12 ±4.02) mm,VAS (6.11 ±0.67);3 months after treatment MMO (36.11 ±4.02),VAS (1.89 ±0.21);6 months after treatment MMO (35.49 ±3.78),VAS (2.21 ±0.32);12 months after treatment MMO (31.53 ±4.87) mm,VAS (3.88 ±0.51)mm,respectively.By statistics,all the measurments showed statistical significance(P ＜ 0.05) between 2 groups.Conclusion:Conservative sequence method is more effective in the treatment of ADDWR.

Study of Lateral Pterygoid Muscle and its Relation with the Maxillary Artery and Buccal Nerve and an Anatomical Classification Based on its Insertion.

Background: Lateral pterygoid muscle plays an important role in the mandibular movements and dynamics of temporomandibualr joint. Anterior displacement of the disc and temporomandibular dysfunction has been related to the insertion of upper head of LPM in the TMJ disc. Materials and Methods: A study was conducted on forty specimens from formalin fixed cadavers in the department of Anatomy , BMCRI, Bangalore. Results and Discussion: In 72.5% of cases the upper head of LPM insert to the disc and blend with the capsule and lower head inserts to the inferior aspect of the disc, to the capsule and the condyle of mandible. Conclusion: Though there is no clear demarcation between the heads of LPM majority of the upper fibers insert to the disc and to the capsule.

MR imaging of the chronic clicking temporomandibular joints / 实用放射学杂志

Objective To analyse the MRI characteristics of the chronic clicking temporomandibular joints(TMJs).Methods 20 TMJs in 10 young chronic clicking individuals (12 clicking TMJs)and 60 TMJs in 30 young healthy volunteers were examined by MRI scanner, and sagittal oblique opened-mouth and closed-mouth position images were observed.Then comparing the MRI findings of the acquired j oints between two groups.Results The ratio of the non-double concave articular disc,slightly high signal intensity in the articular disc, abnormal changes of the condyle,articular fluid,anterior displacement of the articular disc,and increasedDraceangles in the clicking group were significantly higher than those in the control group(P<0.05).The result revealed statistically significant differences.Conclusion The MRI anatomical characteristics can be an indicator for the TMJ anomalys,and provide an obj ective radiological basis for clinical diagnosis and treatment to some extent.

Percentage of lateral pterygoid muscle inserted in the disc of human temporomandibular joint / Porcentaje del músculo pterigoideo lateral inserto en el disco de la articulación temporomandibular humana

Insertion of the upper head of the lateral pterygoid (UHLP) in the temporomandibular joint disc (TMJ) has been linked to anterior displacement of the disc and temporomandibular disfunction. The aim of this study was to determine in human adults, the percentage of muscle fiber in the upper head of the lateral pterygoid muscle inserted in the articular disc. A systematic review of the literature was designed beginning with articles published in Medline, Lilacs and Scielo data bases between the years 1990 and 2010. Key words "Lateral Pterygoid Muscle" and Pterygoid Lateral Muscle" were used, and the term MeSH "Pterygoid Muscle" with Boolean OR "Lateral Ptrerygoid Muscle" AND "Insertion" and the free terms "Pterygoid Lateral Muscle Disc Articular" and "Pterygoid lateral Muscle Meniscus". Of the 156 articles obtained and analyzed, 18 articles meeting eligibility criteria were selected. Based on those articles the percentage of insertion of the CSPL in the TMJ disc was evaluated, each one was subsequently assigned a level of evidence according to OCEBM Oxford Centre Evidence Based Medicine. Only four articles answered the research inquiry, three studies were histological and one used imaging techniques with cross section slices with an adequate evidence level (1B). However, results differed with insertion percentages from 2 percent to 69.8 percent being reported in the superior head of the lateral pterygoid muscle in the articular disc.

La actividad de la inserción de la cabeza superior del pterigoideo lateral (CSPL) en el disco de la articulación temporomandibular (ATM) ha sido vinculada al desplazamiento anterior del disco y disfunción temporomandibular. El propósito de este estudio fue determinar el porcentaje de fibras musculares de la cabeza superior del músculo pterigoideo lateral que se insertan en el disco articular, en humanos adultos. Se diseñó una revisión sistemática de la literatura a partir de artículos primarios publicados en las bases de datos Medline, Lilacs y Scielo entre los años 1990 y 2010. Se utilizaron las palabras clave "Músculo Pterigoideo Lateral" y "Pterygoid Lateral Muscle", el Término MeSH: "Pterygoid Muscle" con los boleanos OR "Lateral Pterygoid Muscle" AND "Insertion" y los Términos Libres: "Pterygoid Lateral Muscle Disc Articular" y "Pterygoid lateral Muscle Meniscus". Se obtuvieron 156 artículos, los cuales fueron analizados y se seleccionaron 18 que cumplieron con los criterios de elegibilidad. En base a estos artículos se evaluó el porcentaje de inserción de la CSPL en el disco de la ATM, posteriormente a cada uno se les otorgó un nivel de evidencia de acuerdo a la clasificación de Oxford Centre Evidence Based Medicine (OCEBM). Solo 4 artículos respondieron a la pregunta de investigación, 3 estudios fueron histológicos y 1 imagenológico, todos con diseños de cortes transversales con buen nivel de evidencia (1b). Sin embargo los resultados fueron disímiles, reportándose porcentajes de inserción del 2 al 69,8 por ciento de la cabeza superior del pterigoideo lateral en el disco articular.

Evaluación histológica e histoquímica de las fibras colágenas y elásticas de los tejidos de la ATM humana / Histological and histochemical evaluation of collagen and elastic fibers in human TMJ tissue

Se estudió la cantidad y distribución de las fibras colágenas y elásticas de los distintos tejidos que conforman la articulación témporomandibular humana (ATM). Se utilizaron diecisiete ATMs humanas. Las muestras fueron procesadas con técnicas histológicas e histoquímicas. Al evaluar la morfología articular, ocho presentaron características histológicas normales y nueve alteradas. La cantidad y distribución de fibras elásticas varió para cada tejido articular en estudio, siendo notable la cantidad de fibras elásticas en la zona anterior y retrodiscal. Se determinó gran cantidad de fibras colágenas tipo I en todos los tejidos articulares. Entre los manojos de colágeno I se encontraron fibras de colágeno tipo III. Estos hallazgos nos indican que la cantidad y distribución de estas fibras están relacionadas con el rol funcional de los tejidos articulares donde ellas se encuentran. No se encontraron diferencias significativas en la cantidad de fibras elásticas, colágenas tipo I y III entre los tejidos conectivos evaluados en articulaciones sanas y enfermas.

The quantity and distribution of collagen and elastic fibers of seventeen human TMJ tissues were studied. Histological and histochemical methods were used. The histological evaluation showed eight TMJs with normal morphology and nine with joint tissue alterations. Elastic fibers amount and distribution was different in every analyzed articular tissue, noting the amount of elastic fibers in the anterior and retrodiscal zones. A great quantity of type I collagen fibers was found in all the joint tissues. Type III collagen fibers were found among the type I collagen bundles. These findings suggest a relationship between function and the amount and distribution of these fibers. No significant difference was found in the quantity of elastic, collagen type I and III fibers among the connective tissues in healthy and sick joints.

Anterior disc displacement and the superior head of lateral pterygoid muscle: a case-control study / Desplazamiento discal anterior y la cabeza superior del músculo pterigoideo lateral: un estudio caso-control

The objective of this study was to assess the association between an increase in the proportion of the superior head of the lateral pterygoid muscle (SHLP) inserted into the temporomandibular joint (TMJ) disc and the presence of anterior disc displacement diagnosed by using MRI. We analyzed 75 images of patients with anterior displacement and 75 controls with normal relationship between the mandibular head and the articular tubercle also diagnosed by MRI. Levels of insertion were measured. Descriptive and analytic statistics were calculated. Analyses of differences were made by Fischer's exact test and also were calculated clinical significance (OR, CI = 95 percent). The average insertion of SHLP was 71.14 percent (SD 14.13) in controls and 67.80 percent (SD.16.23) in cases group. The only relationship that presented a significant association (OR 5.61) was found when comparing subjects with a percentage of inserting the disc into the SHLP at 50 percent with those who had higher levels of insertion (50 percent). Our results suggest that the highest percentage of insertion serves as a protective factor for anterior disc displacement, probably due to greater control of neuromuscular activity.

El objetivo de este estudio fue evaluar la asociación entre el aumento de la proporción de la cabeza superior del músculo pterigoideo lateral (CSPT) insertado en la articulación temporomandibular (ATM) y la presencia de desplazamiento discal anterior diagnosticado mediante resonancia magnética. Se analizaron 75 imágenes de pacientes con desplazamiento discal anterior y 75 controles con una relación normal entre la cabeza de la mandíbula y el tubérculo articular, también diagnosticada por resonancia magnética. Los niveles de inserción fueron medidos. La estadística descriptiva y analítica fueron calculadas. Los análisis de las diferencias se hicieron por la prueba exacta de Fischer, y también se calculó la significancia clínica (OR, IC=95 por ciento). La inserción media de la CSPT fue 71,14 por ciento (DS 14,13) en los controles y 67,80 por ciento (SD 16,23) en los casos de grupo. La única relación que presentó una asociación significativa (OR 5,61) se encontró al comparar los sujetos con un porcentaje de inserción en la CSPT 50 por ciento con aquellos que tenían niveles más altos de inserción (50 por ciento). Nuestros resultados sugieren que el mayor porcentaje de inserción sirve como un factor de protección para el desplazamiento discal anterior, probablemente debido a un mayor control de la actividad neuromuscular.

Frequency of occurence of the discomalleolar ligament in the adult man / Frecuencia aparición del ligamento discomaleolar en el hombre adulto

The discomaleollar ligament is not described in the anatomy textbooks but was demonstrated by Pinto (1962) and others. It is a ligamentous structure connecting the malleus in the tympanic cavity and the articular disc and the capsule of the temporomandibular joint. This anatomical relationship between the middle ear and temporomandibular joint is supposed to be one of the explanations for the otological symptons associated with temporomandibular joint dysfunction. The aim of our study was to determine the frequency of occurence of the discomaleollar ligament. Twenty hemi-heads of adults human were carefully dissected from a superior approach through the middle cranial fossa. The bone of the middle cranial fossa over the temporomandibular joint region and the roof of the tympanic cavity were carefully removed to expose the articular disc, ossicles of the middle ear, lateral pterygoid muscle and other structures in the region. The discomalleolar ligament was found in all studied cases what allow us to suggest that it is an intrinsic ligament of the temporomandibular joint.

El ligamento discomaleolar no se describe en los textos de anatomía, pero ha sido demostrado por Pinto (1962) y otros. Es una estructura ligamentosa que conecta el maléolo en la cavidad timpánica con el disco articular y la cápsula de la articulación temporomandibular. Esta relación anatómica entre el oído medio y la articulación temporomandibular se supone que es una de las explicaciones de los síntomas otológicos asociados a la disfunción temporomandibular. El objetivo de nuestro estudio fue determinar la frecuencia de aparición del ligamento discomaleolar. Veinte hemi-cabezas de individuos adultos fueron cuidadosamente disecadas desde un acceso superior a través de la fosa craneal media. Se retiró el hueso de la fosa craneal media sobre la región de la articulación temporomandibular y el techo de la cavidad timpánica, para exponer el disco articular, osículos del oído medio, músculo pterigoideo lateral y otras estructuras en la región. El ligamento discomaleolar se encontró en todos los casos estudiados, lo que nos permite sugerir que es un ligamento intrínseco de la articulación temporomandibular.

Superior head of the lateral pterygoid muscle inserting in asymptomatictemporomandibular joints / Inserción de la cabeza superior del músculo pterigoideo lateral enarticulaciones temporomandibulares asintomáticas

The constitution and shape of superior head of the lateral pterygoid muscle (SHLP) inserts remains a topic of interest in the literature. The purpose of this study was to analyze by magnetic resonance imaging (MRI) the temporomandibular joint (TMJ) of individuals without signs of temporomandibular dysfunction. One hundred seventy-eight MRI images of one hundred and three patients were utilized, and the surface and percentage of the SHLP insert into the articular disc and condilar process was determined. In women, the average insertion into the disc was found to be between 5.7–5.5mm (SD 1.5–1.3), corresponding to 69.8–70.7 percent of the SHLP. In men, the average insertion into the disc was between 6.2–6.12mm (SD 1.8–1.9), or 68.9–74.2 percent. There were no differences in terms of the sex of the patients or the side of the joint. We found a significant percentage of SHLP fibers embedded in the disc of asymptomatic TMJs, and its role in theanterior disc displacement and the development of the temporomandibular dysfunction should be revised.

La constitución y la forma de inserción de la cabeza superior del músculo pterigoideo lateral (CSMPL) sigue siendo un tema de interés en la literatura. El objetivo de este estudio fue analizar mediante resonancia nuclear magnética (RNM) la articulación temporomandibular (ATM) de individuos sin signos de disfunción temporomandibular. Fueron utilizadas 178 imágenes de RNM pertenecientes a 103 pacientes. Se determinó la superficie y porcentaje de la inserción de la CSMPL en el disco y proceso condilar. En mujeres, la media de inserción en el disco estuvo entre 5,7-5,5 mm (SD 1,5- 1,3) correspondiente al 69,8-70,7 por ciento de la CSMPL. En hombres, la media de inserción en el disco estuvo entre 6,2-6,12mm (SD 1,8-1,9) correspondiente al 68,9-74,2 por ciento de la CSMPL. No hubo diferencias en cuanto al sexo de los pacientes o lado de la articulación. Hemos encontrado un porcentaje significativo de las fibras de la CSMPL insertadas en el disco de ATMs asintomáticas, y su papel en el desplazamiento anterior del disco y el desarrollo de disfunción temporomandibular debe ser revisado.

Prevalence of the third head of the lateral pterygoid muscle: a magnetic resonance image study / Prevalencia de la tercera cabeza del músculo pterigoideo lateral: estudio con imaenes de resonancia magnética

The lateral pterygoid muscle (LPM) is important in the physiology and dysfunction of the temporomandibular joint (TMJ), which has described the presence of a third head in the lateral pterygoid muscle (THLPM). The purpose of this study was to evaluate the prevalence of THLPM and its relationship with the TMJ disc through magnetic resonance imaging (MRI). It was evaluated 178 MRI of the TMJ of healthy individuals, in images that presented THLPM, and these were defined and measured at the surface inserted into the disc. The prevalence of THLPM was 20.22 percent (n = 36). Insertion of THLPM was made entirely on the TMJ disc, the average area of insertion was 4.14mm (SD 1.35) in women and 4.67 (SD 2.68) in men, but these differences were not significant. We concluded that the LPM has a complex structure, and that a THLPM could contribute in the development of TMJ disc function alterations and anterior disc displacement.

El músculo pterigoideo lateral (MPL) tiene importancia en la fisiología y en la disfunción de la articulación temporomandibular (ATM), se ha descrito la presencia de una tercera cabeza en el músculo pterigoideo lateral (TCPL). El propósito de este estudio fue evaluar mediante resonancia nuclear magnética (RNM) la prevalencia de la TCPL y su relación con el disco de la ATM. Se evaluaron 178 RNM de ATM de individuos sanos. En las imágenes que presentaron TCPL éstos fueron delimitados y se midió la superficie inserta en el disco. La prevalencia de la TCPL fue del 20,22 por ciento (n=36). La inserción de la TCPL se realizó completamente en el disco de la ATM, la media del área de inserción fue de 4,14mm (DS. 1,35) en mujeres y 4,67 (DS. 2,68) en hombres, estas diferencias no resultaron significativas. Concluimos que el MPL presenta una estructura compleja y que una TCPL podría participar en el desarrollo de alteraciones en la función discal y en la presencia de desplazamiento anterior del disco.

Effect of hepatocyte growth factor on the repair of defect in the articular disc in rabbit temporomandibular joint

An experimental study of the remodeling mechanism of the retrodiscal tissues by traction of the mandibular ramus and zygomatic arch in rabbits / 实用口腔医学杂志

Objective; To investigate the remodeling mechanism of the retrodiscal tissues of temporomandibular joint after mechanical loading. Methods; 15 adult New Zealand rabbits were subjected to traction between the mandibular ramus and zygomatic arch in the postero-superior direction unilaterally using elastic force. The animals were killed respectively at 2, 4 and 6 weeks. The histologic features were observed by Hematoxylin & Eosin and Alcian blue staining. The expressions of aggre can and collagen II antigen in the articular disc of temporomandibular joint were observed by immunohistochemical staining. Results: The articular disc of the traction side in temporomandibular joint was characterized by an early phase (2 weeks postoperatively) with partial anterior disc displacement and disc deformity and subsequently in deposition of fibrous material in the matrix of the retrodiscal tissues. With time going on, fibroblasts significantly decreased and connective tissues increased. A small quantity of cartilage-like cells were also investigated in that area. However, no obvious histological change was observed in the control group. Compared with the control group, glycosaminoglycan, ag-grecan and collagen II were weakly positive in the intermediate zone of articular disc in experimental group. Aggrecan was stronger positive in the intermediate zone of articular disc after two weeks in experimental group. When traction period prolonged, glycosaminoglycan, aggrecan and collagen II were strong positive in the retrodiscal tissue of articular disc in experimental group. Conclusion; These investigations reveal that distracting mandibule towards rear and top through ansa capitis, the synthesis of cartilage matrix increase and a small quantity of cartilage cells appear to adjust to its functions.

Changes in the shape and ultrastructure of the articular disc of the rat mandibular joint with aging / 대한치과교정학회지

The purpose of this study was to investigate changes in the shape and ultrastructure of the articular disc of the rat mandibular joint with aging. Mechanical stress applied to the articular disc changes during neonatal, suckling, juvenile, adult and senile stages. Mandibular joints of 6 groups of rats(l-, 7-, 17-, 27-, 55-day and over-1-year groups) were removed en bloc and processed for light and electro microscopic study. The changes in the shape of articular disc were examined by light microscope in each group. Structural and ultrastructural changes in the articular disc were examined by light and electron microscope in each group. The results were as follows : In the 1-day and 7-day groups, the articular disc was long and slender in shape and the articular disc was not fitted with the shape of the mandibular fossa and condyle. However, after that time, the anterior and posterior portions of the articular disc were more bulged and the middle portion was shorter and biconcave. Thus the articular disc was well fitted with the shape of the mandibular fossa and condyle. The cell density decreased with aging. In the 1-day and 7-day groups, the Golgi apparatus, rough endoplasmic reticulum and free ribosome, which are involved in the synthesis of intracellular and extracellular matrix, were developed. In the 17-day, 27-day and 55-day groups, not only the cell organelles involved in the synthesis of the intracellular and extracellular matrix but also the cell organelles involved in the remodeling of the extracellular matrix(i.e., finger-like cell process, lysosome and mitochondria)were well developed. With advancing age, intracytoplasmic microfilaments were more accumulated and condroid cells increased. In the over-1-year group, the majority of cells of the articular disc were chondroid cells. The majority of cytoplasmic compartment were filled with intracytoplasmic microfilaments and cell organelles were not developed. Therefore, metabolic activities of the cell was markedly reduced and cells contained structures enduring mechanical stress, and cells which were in the process of degeneration were observed occasionally.

Changes in the shape and ultrastructure of the articular disk of rat following postural hyperpropulsor / 대한치과교정학회지

This study was conducted to examine the changes in the shape of the Sprague-Dawley rats' articular disk following postural hyperpropulsion by observing their articular specimens through light and electronic microscopes after following 2-week and 4-week postural hyperpropulsion from their four weeks of age. The findings of this study are summarized as follows, It was shown that as compared with the control group, the experimental group indicated a significant increase in thickness of the 2-week groups' anterior and postreior portion of the articular disc. The experimental group showed statistically more significant increase in thickness of the 4-week groups' anterior portion of the articular disc than the control group. Light micrograph showed that the experimental group had more fibroblast in the anterior portion of the 2-week and 4-week groups than the comparing group. The 2-week groups showed in the findings through the electronic microscope that there were found the well developed and dilated HER which seems to actively synthesize the extracellular matrix including collagen, the cells with the well developed RER without distention which seems to actively synthesize the intracellular microfilaments due to the well developed free ribosome, and the typical chondroid cells. In addition, there was more fibroblast cell with the distended and well developed RER in the anterior area of the experimental group than that of the control group. The 4 week experimental group's anterior area of the disk had more cells than that of the control group while fibroblast with the well developed RER and free ribosome was quite abundant. Based on the above result of this study, it was shown that the functional hyperpropulsion of the mandible causes the changes in the nature of the mechanical load to the certain portion of the articular disk. As a result, it seems that there may be occurred some changes in morphology of the disc by adaptation or confrontation with these changes at the cellular level.