Estudo histológico e imunohistoquímico da degeneração da região central da cartilagem de Meckel na mandíbula em desenvolvimento de ratos / Histological and immunohistochemical study of the degeneration of the central region of Meckel's cartilage in the developing mandible of rats

A cartilagem de Meckel é uma estrutura transitória embrionária presente durante os estágios iniciais da formação da mandíbula, localizada em toda sua extensão e dividida em três porções, anterior, intermediária e posterior. O enfoque deste trabalho foi direcionado à elucidação do destino final da porção intermediária por meio de um estudo temporal sequenciado. Por isso, foi investigado a presença de células de reabsorção e a presença de fibras colágenas, bem como da proteína óssea osteopontina (OPN) na cartilagem de Meckel na região do germe do 1º molar inferior e no seu entorno. Foram utilizados fetos de ratos Wistar em períodos gestacionais pré-estabelecidos, G18 a G21 (grupos de dias intrauterinos), bem como P0 e P1 (recém-nascidos) para remoção das cabeças. Em sequência, os espécimes foram fixados em solução de formaldeído 4% + glutaraldeído 0,1% com tampão fosfato 0,1M, descalcificados em EDTA 4,13%, desidratados em concentrações crescentes de etanol e incluídos em parafina. As amostras foram coradas em hematoxilina e eosina (HE) e tricrômico de Mallory para análise histológica. Adicionalmente, os grupos G19 a P0 foram submetidos à reação histoquímica de TRAP para determinação da presença de células clásticas. Além disso, os grupos G21 e P0 (dia do nascimento) passaram por reações de imunomarcação para análise da expressão de OPN. Foi observado a degeneração gradual da cartilagem com a observação de mudanças estruturais, a justaposição de células clásticas na superfície da cartilagem por reação histoquímica TRAP a partir do G21, o aparecimento de colágeno tipo I nas fases terminais da degeneração, assim como a marcação positiva para a osteopontina na superfície de G21 e em todo o remanescente da cartilagem de Meckel no grupo P0. O estudo apontou um processo de degeneração da cartilagem com evidências de formação de matriz mineralizada de natureza óssea, a qual foi reabsorvida por células clásticas, sugerindo a ossificação da porção intermediária da cartilagem de Meckel.

Sex Determination in the Contemporary Chilean Population by Mandible Analysis in Panoramic Radiographies / Estimación Sexual de la Población Chilena Contemporánea Mediante Análisis de la Mandíbula en Radiografías Panorámicas

SUMMARY: Sex identification of a deceased human individual by means of the mandible is very important for forensic dentistry. The aim of the present study was to determine the sex of Chilean individuals by mandible analysis in panoramic radiographies. Linear and angular parameters of the mandible were analyzed from panoramic radiographies (PR). The study included PR of adult Chilean individuals, of both sexes, with optimum solution and contrast, and which allowed the angles and rami of the mandible to be viewed. Sex was determined by univariate and bivariate discriminant function analysis. The sample consisted of 594 PR of individuals aged between 18 and 84 years. The best sex predictor using univariate discriminant function analysis was the mandibular ramus height (MRH) (74.1 %), followed by the distance from the mental foramen - mandibular base (DMF-MB) (69.1 %) and the bicondylar breadth (BC) (66.7 %). The parameters that presented the lowest sex prediction were the angle of the mandible (AM) with 55.0 % and the distance between mental foramina (DMF) with 53.7 %. The best sex prediction was obtained by the step model of discriminant function analysis (80.2 %), including only three parameters: MRH, BC and DMF-MB. The parameters height of the mandibular ramus, bicondylar breadth and distance from the mental foramen - base of the mandible are good predictors of sex in Chilean individuals when used in conjunction; they are therefore indicated for sex determination in the contemporary Chilean population.

La identificación humana de un individuo fallecido a través de la mandíbula es muy relevante para la odontología forense. El objetivo de este estudio fue estimar el sexo de individuos Chilenos a través del análisis de la mandíbula, utilizando radiografías panorámicas. Fueron analizados parámetros lineales y angulares de la mandíbula, a través de radiografías panorámicas (RP). Se incluyeron RP de individuos chilenos adultos, ambos sexos, con solución y contraste óptimos, y que permitían la visualización de los ángulos y ramas de la mandíbula. Se realizó análisis por función discriminante univariada y bivariada para estimación del sexo. Fueron incluidas 594 RP de individuos entre 18 y 84 años. Para el análisis de función discriminante univariado, la altura de la rama mandibular (ARM) fue el parámetro más predictivo (74,1 %), seguido de la distancia foramen mentoniano - base de la mandíbula (DFM-BM) (69,1 %) y el ancho bicondilar (ABCo) (66,7 %). Los parámetros que presentaron menor predicción sexual fueron el ángulo de la mandíbula (AM) con un 55,0 % y la distancia inter-forámenes mentonianos (DIFM), con el 53.7 %. El análisis por pasos fue el modelo de análisis de función discriminante que presentó la mayor predicción sexual (79,5 %), en el cual fueron incluidos sólo tres parámetros: ARM, ABCo y DFM-BM. Los parámetros altura de la rama de la mandíbula, ancho bicondilar y distancia desde el foramen mentoniano hasta la base de la mandíbula son buenos predictores del sexo en individuos Chilenos cuando utilizados en conjunto y están indicados para estimar el sexo en la población chilena contemporánea.

Validity of the Maturation Stage Method in the Individual Assessment of Midpalatal Suture Ossification Before Maxillary Expansion: A Systematic Review / Validez del Método de la Etapa de Maduración en la Evaluación Individual de la Osificación de la Sutura Palatina Mediana Previo a la Expansión Maxilar: Una Revisión Sistemática

In 2013, midpalatal suture maturation stage assessment was proposed for the evaluation of patients before performing maxillary expansion. In this study, we aimed to analyze the association between the midpalatal suture maturation stages assessed by CBCT, according to the method described by Angelieri et al., and other objective methods used to assess skeletal maturation or bone fusion. A computerized database search was conducted using PubMed, Cochrane Library, SciELO, LILACS, Web of Science, and Scopus, without language restriction. Unpublished literature was searched on ClinicalTrials.gov, the National Research Register, and Pro-Quest Dissertation Abstracts and Thesis database. Authors were contacted when necessary, and reference lists of the included studies were screened. Search terms included midpalatal suture, maturation, correlation, diagnostic performance, classification, evaluation, assessment, and relationship. Quality assessment was performed using the Observational Cohort and Cross-Sectional Studies tool developed by the National Heart, Lung, and Blood Institute. Eleven studies met the inclusion criteria. Of all the studies included, 81.9% had fair qualit y and 18.1% good quality, respectively. Eight out of eleven studies assessed the correlation between the midpalatal suture maturation method and the skeletal maturity evaluated by CVM method (Spearman's correlation coefficient: 0.244-0.908). Two out of eleven studies evaluated the correlation between midpalatal suture maturation method and the skeletal maturity assessed by HWM method (Spearman's correlation coefficient: 0.904-0.905) Even though midpalatal suture maturation stage assessment needs an exhaustive training and calibration process, it is a valid method to evaluate skeletal maturation or bone fusion. From a clinical perspective, for patients at CS4, CS5 and CS6, an assessment of the midpalatal suture on CBCT is indicated. A similar assessment should be done in patients at SMI 7-9.

En 2013, se propuso un nuevo método para la evaluación del estadio de maduración de la sutura palatina mediana para la evaluación de los pacientes antes de realizar la expansión maxilar. En este estudio, nuestro objetivo fue analizar la asociación entre las etapas de maduración de la sutura palatina mediana evaluada en CBCT, según el método descrito por Angelieri et al., y otros métodos objetivos utilizados para evaluar la maduración esquelética o la fusión ósea. Se realizó una búsqueda en las bases de datos PubMed, Cochrane Library, SciELO, LILACS, Web of Science y Scopus, sin restricción de idioma. Se buscó literatura no publicada en ClinicalTrials.gov, el Registro Nacional de Investigación y la base de datos Pro-Quest Dissertation Abstracts and Thesis. Se estableció contacto con los autores cuando fue necesario y se revisaron las listas de referencias de los estudios incluidos. Los términos de búsqueda incluyeron sutura palatina mediana, maduración, correlación, rendimiento diagnóstico, clasificación, evaluación, valoración y relación. La evaluación de la calidad se realizó mediante la herramienta de Estudios transversales y de cohortes observacionales desarrollada por el Instituto Nacional del Corazón, los Pulmones y la Sangre. Once estudios cumplieron con los criterios de inclusión. Del total de estudios incluidos, el 81.9% tuvo calidad regular y el 18.1% calidad buena, respectivamente. Ocho de once estudios evaluaron la correlación entre el método de maduración de la sutura palatina mediana y la madurez esquelética evaluada por el método CVM (coeficiente de correlación de Spearman: 0.244-0.908). Dos de once estudios evaluaron la correlación entre el método de maduración de la sutura palatina mediana y la madurez esquelética evaluada por el método HWM (coeficiente de correlación de Spearman: 0.904-0.905). Aunque la evaluación del estado de maduración de la sutura palatina mediana necesita un proceso exhaustivo de entrenamiento y calibración, es un método válido para evaluar la maduración esquelética o la fusión ósea. Desde una perspectiva clínica, para pacientes en CS4, CS5 y CS6, está indicada una evaluación de la sutura palatina mediana en CBCT. Se debe realizar una evaluación similar en pacientes con SMI 7-9.

Mechanical Evaluation of Different Stable Internal Fixation Techniques of Sagittal Osteotomy in Mandibular Advance / Evaluación Mecánica de Diferentes Técnicas de Fijación Interna Estable de Osteotomía Sagital en Avance Mandibular

The mandibular advancements performed in orthognathic surgeries can be stabilized with several techniques when using stable internal fixation. This study aims to comparatively evaluate, in vitro, the mechanical strength in a polyurethane mandibular model for four fixation techniques for sagittal split ramus osteotomy mandibular. 60 samples were divided into 4 groups, with 15 units for each group: group A, group B, group C and group D. Advances of 5 mm were made for each subgroup and fixed with 2.0 mm system plates and monocortical screws in the replicas of human hemimandibles in polyurethane resin. The samples were submitted to mechanical tests of linear loading, being evaluated the peak load and peak deformation. Technique B presented higher peak load (Kgf) and techniques A and B presented higher peak strain (p<0.05). Technique D presented lower peak load and lower peak strain (p<0.05). It is concluded that the study based on the development of new techniques for fixation for sagittal osteotomy of the mandibular ramus is of great importance for the advancement of orthognathic surgery, provided by the technical innovation of more favorable plate models.

Los avances mandibulares realizados en cirugías ortognáticas pueden estabilizarse con varias técnicas cuando se utiliza fijación interna estable. Este estudio tuvo como objetivo evaluar comparativamente, in vitro, la resistencia mecánica en un modelo mandibular de poliuretano para cuatro técnicas de fijación para la osteotomía sagital de la rama mandibular. Se dividieron 60 muestras en 4 grupos, con 15 unidades para cada grupo: grupo A, grupo B, grupo C y grupo D. Se realizaron avances de 5 mm para cada subgrupo y se fijaron con placas de sistema de 2,0 mm y tornillos monocorticales en las réplicas de hemimandíbulas humanas en resina de poliuretano. Las muestras fueron sometidas a pruebas mecánicas de carga lineal, siendo evaluadas la carga máxima y la deformación máxima. La técnica B presentó mayor pico de carga (Kgf) y las técnicas A y B presentaron mayor pico de deformación (p<0,05). La técnica D presentó menor carga máxima y menor tensión máxima (p<0,05). Se concluye que el estudio basado en el desarrollo de nuevas técnicas de fijación para la osteotomía sagital de la rama mandibular es de gran importancia para el avance de la cirugía ortognática, proporcionada por la innovación técnica de modelos de placas más favorables.

Biomechanical Behavior Evaluation of a Mandibular Full-Arch Implant-Supported Prosthesis on ZrO2 and TiO2 Monotype Dental Implants / Evaluación del Comportamiento Biomecánico de una Prótesis Implante Soportada de Arcada Completa Mandibular sobre Implantes Dentales Monotipos de ZrO 2 y TiO

This in silico study aimed to evaluate the biomechanical behavior of a full-arch implant-supported prosthesis on titanium and zirconia monotype implants. A 3D mandible containing 1.0 mm thick cortical and cancellous bone was modeled. Four dental implants (3.3 x 10 mm) were inserted into the jaw model in each model. The implants consisted of Titanium (Ti-S group) and Zirconia Monotype/one-piece (Zr-S group). Fixed full-arch implant-supported prostheses were cemented onto the implant. The models were exported to the analysis software and divided into meshes composed of nodes and tetrahedral elements. All materials were considered isotropic, elastic, and homogeneous. Therefore, all contacts were considered bonded, the mandible model was fixed in all directions, applying a static structural axial load of 300 N on the bottom of the fossa of the left mola r teeth. Microstrain and von-Mises stress (MPa) were adopted as failure criteria. Comparable stress and strain values were shown in the peri-implant bone for both groups. However, the Ti-S group presented a lower stress value (1,155.8 MPa) than the Zr-S group (1,334.2 MPa). Regarding bone tissues, the Ti-S group presented 612 µε and the Zr-S group presented 254 µε. The highest strain peak was observed in bone tissues around the implant closer to the load for both groups. Evaluating monotype zirconia and titanium implants, it is suggested that the greater the rigidity of the implant, the greater the concentration of internal stre sses and the less dissipation to the surrounding tissues. Therefore, monotype ceramic implants composed of yttrium-stabilized tetragonal polycrystalline zirconia may be a viable alternative to titanium implants for full-arch prostheses.

El objetivo de este estudio in silico fue evaluar el comportamiento biomecánico de una prótesis implanto soportada de arcada completa sobre implantes monotipo de titanio y zirconia. Se modeló una mandíbula en 3D que contenía tejido óseo cortical y esponjoso de 1,0 mm de espesor. En cada modelo, se insertaron cuatro implantes dentales (3,3 x 10 mm) en el modelo de mandíbula. Los implantes consistieron en Monotipo de Titanio y Zirconia. Sobre el implante se cementaron prótesis implanto soportadas de arcada completa fija. Los modelos se exportaron al software de análisis y se dividieron en mallas compuestas por nodos y elementos tetraédricos. Todos los materiales se consideraron isotrópicos, elásticos y homogéneos. Por lo tanto, todos los contactos se consideraron cementados, el modelo mandibular se fijó en todas las direcciones, aplicando una carga vertical estructural estática de 300 N en el fondo de la fosa de los dientes molares izquierdos. Se seleccionaron la microesfuerzo y la tensión de Von-Mises (MPa) como criterios de falla. Se mostraron valores de tensión y deformación comparables en el hueso periimplantario para ambos grupos. Sin embargo, el grupo Ti-S presentó un valor de estrés menor (1.155,8 MPa) que el grupo Zr-S (1.334,2 MPa). En cuanto a los tejidos óseos, el grupo Ti-S presentó 612 µε y el grupo Zr-S presentó 254 µε. La mayor concentración de deformación en el tejido óseo se observó en los tejidos alrededor del implante más cerca de la carga para ambos grupos. Al evaluar los implantes monotípicos de zirconia y titanio, se sugiere que cuanto mayor sea la rigidez del implante, mayor será la concentración de tensiones internas y menor la disipación a los tejidos circundantes. Por lo tanto, los implantes cerámicos monotipo compuestos de zirconia policristalina tetragonal estabilizada con itrio pueden ser una alternativa viable a los implantes de titanio para prótesis de arcada completa.

Lesión Fibro-ósea de Mandíbula: Un Hallazgo Radiográfico / Fibro-osseous Lesion of the Mandible: A Radiographic Finding

Las lesiones fibro-óseas son consideradas benignas y componen un grupo de patologías de desórdenes que se caracterizan por el reemplazo de un hueso normal por un tejido compuesto de fibras colágenas, fibroblastos y tejido mineralizado. Presentamos un hallazgo radiográfico obtenido de un paciente de sexo masculino de 41 años de edad que asiste a un centro de radiología para realizarse una radiografía panorámica, el examen revela un interesante hallazgo radiográfico en la hemi mandíbula izquierda, donde se observa una lesión fibro-ósea con expansión ósea a nivel de reborde marginal y cortical basal mandibular, desplazamiento de canal mandibular, desplazamiento dentario, compromiso de cortical alveolar y rizálisis en diferentes niveles en los dientes adyacentes a la lesión. De acuerdo a los antecedentes anteriores se establece una hipótesis diagnóstica de Fibroma Osificante de larga data debido a su radiopacidad. La Organización Mundial de la Salud lo clasifica como una neoplasia ósea benigna con afección al esqueleto craneofacial, de mayor incidencia en mandíbula, se presenta generalmente entre la 3º y 4º década de vida. Concluimos que las lesiones fibro-óseas pueden ser detectadas como un hallazgo radiográfico, esto es relevante para un tratamiento precoz, sin embargo, el diagnóstico debe realizarse complementando los antecedentes clínicos e histopatológicos de la lesión, poniendo especial atención en el diagnóstico diferencial.

Fibro-osseous lesions are considered benign and make up a group of disorder pathologies that are characterized by the replacement of normal bone by tissue composed of collagen fibers, fibroblasts, and mineralized tissue. We present a radiographic finding obtained from a 41-year-old male patient who attended a radiology center for a panoramic radiograph. The examination revealed an interesting radiographic finding in the left hemi-mandible, where a fibro-osseous lesion was observed. with bone expansion at the level of the marginal ridge and basal mandibular cortex, displacement of the mandibular canal, dental displacement, compromise of the alveolar cortex and rizalysis at different levels in the teeth adjacent to the lesion. According to the previous antecedents, a long-standing diagnostic hypothesis of Ossifying Fibroma is established due to its radiopacity. The World Health Organization classifies it as a benign bone neoplasm affecting the craniofacial skeleton, with the highest incidence in the jaw, generally presenting between the 3rd and 4th decade of life. We conclude that fibro-osseous lesions can be detected as a radiographic finding, this is relevant for early treatment, however the diagnosis must be made by complementing the clinical and histopathological history of the lesion, paying special attention to the differential diagnosis.

Concordance of the vestibular bone thickness at the level of point a between teleradiography and cone beam computed tomography / Concordancia del espesor óseo vestibular a nivel del punto a entre telerradiografía y tomografía computarizada de haz cónico

Objective: The aim of this study was to determine the concordance of the vestibular bone thickness measured at the level of point A between Teleradiography and Cone Beam Computed Tomography (CBCT). Materials and Methods: This study consisted of a cross-sectional analytical design of concordance that evaluated the teleradiographies and CBCTs of 32 patients. The measurements were performed by three evaluators, specialists in orthodontics. Two of them measured the CBCTs and one evaluated the teleradiographs. The concordance of both tests was determined using the Concordance Correlation Coefficient. Results: When evaluating the value of the vestibular bone thickness at the level of point A between the CBCT and the teleradiography, it was observed that the mean value of the absolute difference between the two was 0.95±0.74, 95%CI [0.68­1.22], being statistically significant (p=0.0027). When the concordance between both tests was analyzed, it was observed that it was poor (CCC=0.204 95%CI [0.014­0.394]), although statistically significant (p<0.00001). Conclusions: It was possible to conclude that there is no concordance in the measurement of the vestibular bone thickness at the level of Point A between the Teleradiography and the CBCT.

Objetivo: El objetivo de este estudio fue determinar la concordancia del espesor óseo vestibular medido a nivel del punto A entre la Telerradiografía y la Tomografía computarizada de haz cónico (CBCT). Materiales y Métodos: Esta investigación presentó un diseño analítico transversal de concordancia en el que se evaluaron las telerradiografías y CBCT de 32 pacientes. Las mediciones fueron realizadas por tres evaluadores especialistas en ortodoncia, dos de ellos midieron los CBCT y uno las telerradiografías. La concordancia de ambos exámenes fue medida mediante Coeficiente de Correlación de Concordancia. Resultados: Al evaluar el valor del grosor óseo vestibular a nivel del punto A entre el CBCT y la telerradiografía, se observó que el valor promedio de diferencia absoluta entre ambos fue de 0,95±0,74 IC95% [0,68­1,22], siendo estadísticamente significativas (p=0,0027). Cuando se analizó la concordancia entre ambos exámenes se observó que esta fue pobre (CCC=0,204 IC95 % [0,014­0,394]), aunque estadísticamente significativa (p<0,00001). Conclusión: Se pudo concluir que no existe concordancia en la medición del espesor óseo vestibular medido a nivel del Punto A entre la Telerradiografía y el CBCT.

Diagnóstico e tratamento de extenso cisto dentígero mandibular em um paciente pediátrico / Diagnosis and treatment of extensive mandibular dentigerous cyst in a pediatric patient

Introdução: lesões gnáticas pediátricas são comumente assintomáticas e diagnosticadas em exames de imagem de rotina. Entretanto, algumas podem cursar com dor, assimetria facial, destruição óssea e rápida evolução, requerendo diagnóstico preciso e precoce. Objetivo: o objetivo desse estudo é reportar o processo de diagnóstico e tratamento de um extenso cisto dentígero (CD) em um paciente pediátrico. Relato do caso: um menino de 5 anos idade apresentou queixa de aumento de volume doloroso na região posterior de mandíbula com tempo de evolução de 4 meses. A tomografia computadorizada demonstrou uma imagem hipodensa, bem delimitada, envolvendo a coroa do dente 37, causando a expansão da cortical vestibular e erosão da cortical lingual, com aproximadamente 3cm. Com as hipóteses diagnósticas de fibroma ameloblástico ou CD, a lesão foi enucleada totalmente. Microscopicamente, observou-se uma lesão cística com revestimento epitelial odontogênico, áreas de hiperplasia e exocitose, além de cápsula de tecido conjuntivo densamente colagenizado, com áreas de hemorragia e infiltrado inflamatório linfoplasmocitário. Resultados: baseado nas características clínicas, imagenológicas e histopatológicas, o diagnóstico final foi de CD inflamado. O paciente continua em acompanhamento clínico e radiográfico, com ausência de recidiva. Conclusão: CD inflamados em pacientes pediátricos podem apresentar comportamento peculiar e mimetizar outras lesões de natureza odontogênica. O diagnóstico precoce permite uma menor morbidade associada aos tratamentos cirúrgicos.

Introduction: pediatric gnathic lesions are commonly asymptomatic and diagnosed in routine imaging exams. However, some of them may cause pain, facial asymmetry, bone destruction and rapid evolution, requiring accurate and early diagnosis. Objective: the aim of this study is to report the diagnosis and treatment of an extensive dentigerous cyst (DC) in a pediatric patient. Case report: a 5-year-old boy complained of painful swelling in the posterior region of the mandible with an evolution time of 4 months. Computed tomography showed a hypodense, well-delimited image involving the crown of tooth 37, causing buccal cortical expansion and lingual cortical erosion, measuring approximately 3cm. With the diagnostic hypotheses of ameloblastic fibroma or DC, the lesion was completely enucleated. Microscopically, a cystic lesion with an odontogenic epithelial lining with areas of hyperplasia and exocytosis was observed, in addition to a densely collagenous connective tissue capsule, with areas of hemorrhage and lymphoplasmacytic inflammatory infiltrate. Results: based on clinical, imaging and histopathological characteristics, the final diagnosis was inflamed DC. The patient remains under clinical and radiographic follow-up, with no recurrence. Conclusion: inflamed DC in pediatric patients may show a peculiar behavior and mimic other odontogenic lesions. Early diagnosis allows for lower morbidity associated with surgical treatments.

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.

Frecuencia de la cavidad ósea de Stafne. Un análisis retrospectivo en radiografías panorámicas / Frequency of Stafne's bone cavity. A retrospective analysis in panoramic radiographs

Introducción: La cavidad ósea de Stafne es una variante anatómica poco frecuente, radiolúcida y bien delimitada, que usualmente se presenta en la región molar cerca del ángulo mandibular y por debajo del canal para el nervio dentario inferior. Es frecuente que sea erróneamente diagnosticada con otras entidades de carácter patológico. Objetivo: Determinar la frecuencia de la cavidad ósea de Stafne en las radiografías panorámicas del Servicio de Radiología Oral y Maxilofacial del Centro Dental Docente "Cayetano Heredia", desde 2015 hasta 2019. Métodos: Se realizó un estudio observacional, descriptivo, transversal y retrospectivo de una muestra de 17875 radiografías panorámicas. Se consideraron las variables demográficas como el sexo, la edad, la localización y la forma, posteriormente se realizaron tablas de contenido para el análisis de los datos. Resultados: Entre los 17875 pacientes, solo 24 (0,13 por ciento) presentaban cavidad ósea de Stafne, incluidos 16 hombres y 8 mujeres. La octava década de vida presentó la mayor cantidad de casos con 6 (0,4 por ciento). La localización posterior derecha contó con 13 (54,17 por ciento), la posterior izquierda con 7 (29,17 por ciento) y la anterior con 4 (16,67 por ciento). La forma ovalada con 23 (95,83 por ciento) y la redonda solo con 1 (4,17 por ciento). Conclusiones: La frecuencia de la cavidad ósea de Stafne fue de 0,13 por ciento con predilección del sexo masculino, la octava década de vida, la localización posterior derecha y la forma ovalada(AU)

Introduction: Stafne's bone cavity is a rare, radiolucent, well-demarcated anatomic variant that usually occurs in the molar region near the mandibular angle and below the canal for the inferior dental nerve. It is frequently misdiagnosed with other pathological entities. Objective: To determine the frequency of Stafne's bone cavity in panoramic radiographs of the Oral and Maxillofacial Radiology Service of the Teaching Dental Care Center "Cayetano Heredia", from 2015 to 2019. Methods: An observational, descriptive, cross-sectional and retrospective study was performed on a sample of 17875 panoramic radiographs. Demographic variables such as gender, age, location and shape were considered; subsequently tables of contents were performed for data analysis. Results: Among the 17875 patients, only 24 (0.13 percent) had Stafne's bone cavity, including 16 males and 8 females. The eighth decade of life presented the highest number of cases with 6 (0.4 percent). The right posterior location accounted for 13 (54.17 percent), the left posterior with 7 (29.17 percent) and the anterior with 4 (16.67 percent). The oval shape with 23 (95.83 percent) and round with only 1 (4.17 percent). Conclusions: The frequency of Stafne's bone cavity was 0.13 percent with male sex predilection, eighth decade of life, right posterior location and oval shape(AU)

Defeito ósseo de Stafne uma depressão lingual na mandíbula: revisão da literatura / Stafne's bone defect a lingual depression in the jaw: literature review

O defeito ósseo de Stafne foi considerado por muito tempo como um cisto ósseo por se apresentar radiograficamente de forma radiolúcida, circunscrita, com bordas delimitadas e em quase todos os casos unilateral. Hoje em dia já se sabe que é uma depressão e/ou cavidade óssea causada pelo alojamento da glândula submandibular ou parte dela e/ou seus tecidos adjacentes na região posterior da mandíbula, ou na região anterior em casos mais raros pelo alojamento da glândula sublingual. Sendo assim, o objetivo deste trabalho é realizar uma breve revisão da literatura acerca das características mais frequentes e suas variações desta anomalia anatômica. As buscas foram realizas em periódicos de artigos científicos publicado nas bases de dados eletrônicas: PubMed, Scielo e Google Acadêmico, contendo artigos científicos dos últimos dez anos nos idiomas inglês e português. Os dados mostram que o defeito ósseo de stafne tem predileção pelo sexo masculino, é assintomática, pois se trata de uma alteração anatômica, não requer tratamento, portanto cabe ao cirurgião dentista ter conhecimento, uma vez que este é encontrado de forma ocasional em radiografias panorâmicas para investigação de outras circunstancias, e que muitas vezes acaba levando o profissional odontólogo a realizar diagnósticos errôneos ou exames mutiladores como a biopsia que são desnecessários nesta situação pelo fato desta variação anatômica ter características muitos semelhantes aos cistos.

Stafne's bone defect was considered for a long time as a bone cyst because it presents radiographically in a radiolucent, circumscribed form, with delimited borders and, in almost all cases, unilateral. Nowadays it is known that it is a depression and / or bone cavity caused by the accommodation of the submandibular gland or part of it and / or its adjacent tissues in the posterior region of the mandible, or in the anterior region in rarer cases by the accommodation of the sublingual gland. Therefore, the objective of this work is to carry out a brief literature review of the more specific characteristics and their variations of this anatomical anomaly. Searches were performed in journals of scientific articles published in electronic databases: PubMed, Scielo and Academic Google, containing scientific articles from the last ten years in English and Portuguese. The data show that the stafne bone defect has a predilection for males, it is asymptomatic, as it is an anatomical alteration, does not require treatment, therefore it is up to the dental surgeon to be aware, once panoramic to investigate other circumstances, and that many Sometimes it ends up leading the dental professional to perform misdiagnosis or mutilating tests such as a biopsy, which are unnecessary in this situation because this anatomical variation has characteristics that are very similar to cysts.

Automated diagnostic classification with lateral cephalograms based on deep learning network model / 中华口腔医学杂志

Objective: To establish a comprehensive diagnostic classification model of lateral cephalograms based on artificial intelligence (AI) to provide reference for orthodontic diagnosis. Methods: A total of 2 894 lateral cephalograms were collected in Department of Orthodontics, Capital Medical University School of Stomatology from January 2015 to December 2021 to construct a data set, including 1 351 males and 1 543 females with a mean age of (26.4± 7.4) years. Firstly, 2 orthodontists (with 5 and 8 years of orthodontic experience, respectively) performed manual annotation and calculated measurement for primary classification, and then 2 senior orthodontists (with more than 20 years of orthodontic experience) verified the 8 diagnostic classifications including skeletal and dental indices. The data were randomly divided into training, validation, and test sets in the ratio of 7∶2∶1. The open source DenseNet121 was used to construct the model. The performance of the model was evaluated by classification accuracy, precision rate, sensitivity, specificity and area under the curve (AUC). Visualization of model regions of interest through class activation heatmaps. Results: The automatic classification model of lateral cephalograms was successfully established. It took 0.012 s on average to make 8 diagnoses on a lateral cephalogram. The accuracy of 5 classifications was 80%-90%, including sagittal and vertical skeletal facial pattern, mandibular growth, inclination of upper incisors, and protrusion of lower incisors. The acuracy rate of 3 classifications was 70%-80%, including maxillary growth, inclination of lower incisors and protrusion of upper incisors. The average AUC of each classification was ≥0.90. The class activation heat map of successfully classified lateral cephalograms showed that the AI model activation regions were distributed in the relevant structural regions. Conclusions: In this study, an automatic classification model for lateral cephalograms was established based on the DenseNet121 to achieve rapid classification of eight commonly used clinical diagnostic items.

Isolated metastasis of the ascending ramus of the mandible of thyroid follicular carcinoma: a case report / 临床耳鼻咽喉头颈外科杂志

The mandibular metastatic spread of carcinoma from the thyroid gland is exceedingly rare. Follicular thyroid carcinoma is the second most common type of thyroid carcinoma，accounting for approximately 10% to 15% of all thyroid cancers. The prognosis of FTC is relatively satisfactory. Due to its rich blood transport, it is easy to metastasize hematological, with the main sites of metastasis are bone and lung. However，mandibular metastasis of thyroid follicular carcinoma is rare. We report a case of thyroid follicular carcinoma that metastasized to the ascending ramus of the mandible 21 years after surgery.The operation was successfully completed, and there was no recurrence during postoperative follow-up. Due to the absence of obvious clinical symptoms in the patient, the diagnosis and treatment were challenging. We have provided detailed radiographic and pathological images to facilitate understanding and discussion of the disease.

Research progress in effect of chewing-side preference on temporomandibular joint and its relationship with temporo-mandibular disorders / 浙江大学学报·医学版

Chewing-side preference is one of the risk factors for temporomandibular disorders (TMD), and people with chewing-side preference is more prone to have short and displaced condyles, increased articular eminence inclination and glenoid fossa depth. The proportion of TMD patients with chewing-side preference is often higher than that of the normal subjects. Clinical studies have shown a strong correlation between chewing-side preference and TMD symptoms and signs; and animal studies have shown that chewing-side preference can affect the growth, development, damage and repair of the mandible. After long-term unilateral mastication, changes in the stress within the joint cause the imbalance of temporomandibular joint (TMJ) structural reconstruction, the transformation and even destruction of the fiber structure of masticatory muscle, resulting in uncoordinated movement of bilateral muscles. The joint neurogenic diseases caused by the increase of neuropeptide substance P and calcitonin-gene-related-peptide (CGRP) released locally by TMJ may be the mechanism of TMD. This article reviews the research progress of the influence of chewing-side preference on the structure of TMJ, the relationship between chewing-side preference and TMD, and the related mechanisms.

Implications of occlusal plane in diagnosis and treatment of malocclusion / 浙江大学学报·医学版

Occlusal plane (OP) is one of the essential factors affecting craniofacial morphology and function. The OP not only assists in diagnosing malocclusion but also serves as an important reference for making treatment plans. Patients with different types of malocclusions have different forms of OP. Compared with patients with standard skeletal facial type, the occlusal plane of patients with skeletal class Ⅱ and high angle is steeper, while that of patients with skeletal class Ⅲ and low angle is more even. In orthodontic treatment, adjusting and controlling the OP can promote the normal growth and development of the mandible in most patients with malocclusion during the early stage of growth, while causing favorable rotation of the mandible in some adults with mild-to-moderate malocclusion. For moderate-to-severe malocclusion, the OP rotation by orthodontic-orthognathic treatment can achieve better long-term stability. This article reviews the evolution of the definition of OP and its implications for diagnosing and the guiding treatment of malocclusion.

Automatic determination of mandibular landmarks based on three-dimensional mandibular average model / 北京大学学报(医学版)

OBJECTIVE@#To explore an efficient and automatic method for determining the anatomical landmarks of three-dimensional(3D) mandibular data, and to preliminarily evaluate the performance of the method.@*METHODS@#The CT data of 40 patients with normal craniofacial morphology were collected (among them, 30 cases were used to establish the 3D mandibular average model, and 10 cases were used as test datasets to validate the performance of this method in determining the mandibular landmarks), and the 3D mandibular data were reconstructed in Mimics software. Among the 40 cases of mandibular data after the 3D reconstruction, 30 cases that were more similar to the mean value of Chinese mandibular features were selected, and the size of the mandibular data of 30 cases was normalized based on the Procrustes analysis algorithm in MATLAB software. Then, in the Geomagic Wrap software, the 3D mandibular average shape model of the above 30 mandibular data was constructed. Through symmetry processing, curvature sampling, index marking and other processing procedures, a 3D mandible structured template with 18 996 semi-landmarks and 19 indexed mandibular anatomical landmarks were constructed. The open source non-rigid registration algorithm program Meshmonk was used to match the 3D mandible template constructed above with the tested patient's 3D mandible data through non-rigid deformation, and 19 anatomical landmark positions of the patient's 3D mandible data were obtained. The accuracy of the research method was evaluated by comparing the distance error of the landmarks manually marked by stomatological experts with the landmarks marked by the method of this research.@*RESULTS@#The method of this study was applied to the data of 10 patients with normal mandibular morphology. The average distance error of 19 landmarks was 1.42 mm, of which the minimum errors were the apex of the coracoid process [right: (1.01±0.44) mm; left: (0.56±0.14) mm] and maximum errors were the anterior edge of the lowest point of anterior ramus [right: (2.52±0.95) mm; left: (2.57±1.10) mm], the average distance error of the midline landmarks was (1.15±0.60) mm, and the average distance error of the bilateral landmarks was (1.51±0.67) mm.@*CONCLUSION@#The automatic determination method of 3D mandibular anatomical landmarks based on 3D mandibular average shape model and non-rigid registration algorithm established in this study can effectively improve the efficiency of automatic labeling of 3D mandibular data features. The automatic determination of anatomical landmarks can basically meet the needs of oral clinical applications, and the labeling effect of deformed mandible data needs to be further tested.

Decompensation effectiveness and alveolar bone remodeling analysis of mandibular anterior teeth after preoperative orthodontic treatment in high-angle patients with skeletal class Ⅱ malocclusion / 北京大学学报(医学版)

OBJECTIVE@#To evaluate the decompensation effectiveness and alveolar bone remodeling of mandibular anterior teeth after preoperative orthodontic treatment in high-angle patients with skeletal class Ⅱ malocclusion using lateral cephalogram and cone-beam computed tomography (CBCT).@*METHODS@#Thirty high-angle patients with skeletal class Ⅱ malocclusion who had received preoperative orthodontic treatment and orthognathic surgery in Peking University School and Hospital of Stomatology between Ja-nuary 2017 and August 2022 and had taken lateral cephalogram and CBCT before and after preoperative orthodontic treatment were selected. Items were measured with lateral cephalogram including: The lower central incisor (L1)-Frankfort plane angle (L1-FH), the L1-mandibular plane angle (L1-MP), the L1-nasion-supramental angle (L1-NB) and the vertical distance from the incisal edge of lower central incisor to NB line (L1-NB distance), etc. The incidence of dehiscence/fenestration and the length of dehiscence at labial side (d-La) and lingual side (d-Li) were measured using CBCT. Pearson correlation analysis was used to evaluate the correlation between the changes of d-Li of L1 and age, duration of preoperative orthodontic treatment and the cephalometric measurements before preoperative orthodontic treatment to screen out risk factors affecting the periodontal risk of preoperative orthodontic treatment in high-angle patients with skeletal class Ⅱ malocclusions.@*RESULTS@#After preoperative orthodontic treatment, L1-FH, L1-MP, L1-NB and L1-NB distances changed by 11.56°±5.62°, -11.13°±5.53°, -11.57°±5.43° and (-4.99±1.89) mm, respectively, and the differences were all statistically significant (P < 0.05). Among the 180 measured mandibular anterior teeth, 45 cases with labial dehiscence/fenestration before preoperative orthodontic treatment (T0) had no longer labial dehiscence/fenestration after preope-rative orthodontic treatment (T1); 142 cases without lingual dehiscence/fenestration at T0 had lingual dehiscence/fenestration at T1. After preoperative orthodontic treatment, the d-La of lower lateral incisors (L2), lower canines (L3) and lower anterior teeth (L1+L2+L3) decreased by (0.95±2.22) mm, (1.20±3.23) mm and (0.68±2.50) mm, respectively, and the differences were statistically significant (P < 0.05); the d-Li of L1, L2, L3 and L1+L2+L3 increased by (4.43±1.94) mm, (4.53±2.35) mm, (3.19±2.80) mm and (4.05±2.46) mm, respectively, and the differences were statistically significant (P < 0.05). The increase of d-Li of L1 was positively correlated with L1-FH (r=0.373, P=0.042).@*CONCLUSION@#This study showed that high-angle patients with skeletal class Ⅱ ma-locclusion could achieve ideal decompensation effect of mandibular anterior teeth after preoperative orthodontic treatment with bilateral mandibular first premolars extracted, but the lingual periodontal risk of mandibular anterior teeth was increased. This risk could be correlated to L1-FH before preoperative orthodontic treatment, which should be paid more attention in the design of orthodontic-orthognathic surgical treatment.

Diversity of root canal morphology in mandibular first premolars and its clinical strategies / 中华口腔医学杂志

It is a basic prerequisite for the successful completion of endodontic treatment to thoroughly understand the root canal space anatomy. With the development of dental devices in dentistry, the root canal morphology of the mandibular first premolars can be presented in more detail. Before conducting root canal therapy on the mandibular first premolar with complex root canal morphology, it should be necessary to evaluate the potential difficulties and risks for making an appropriate treatment plan. The present paper reviews the research progress on the diversities of root canal morphology in mandibular first premolars in recent years, and then makes technologic recommendations based on the morphology diversities.

Study on mandibular movement trajectory and virtual occlusal pre-adjustment under light and heavy bite force / 中华口腔医学杂志

Objective: To investigate the influence of light and heavy bite force on the mandibular movement trajectories, and the influence of bite force on virtual occlusal pre-adjustment of digital full crown. Methods: From October 2021 to March 2022, 10 postgraduate volunteers (3 males and 7 females, aged 22-26 years) were recruited from Peking University School and Hospital of Stomatology. Maxillary and mandibular digital models of the participants were obtained by intraoral scanning. Jaw relations were digitally transferred under heavy bite force and mandibular movement trajectories under light and heavy bite force were recorded by jaw motion analyser. Three mandibular markers were chosen, namely the mesial proximal contact point of the central incisor (incisal point) and the mesial buccal cusp tips of the bilateral first molars. The three-dimensional displacements of the markers under two kinds of bite force in the intercuspal position (ICP), the sagittal projection of the three-dimensional displacements in the protrusive edge-to-edge position, and the coronal projection of the three-dimensional displacements in the lateral edge-to-edge position of upper and lower posterior teeth were measured. Single-sample t-test was used to compare the three-dimensional displacements and the corresponding sagittal projection and coronal projection with 0, respectively. The left maxillary central incisor and left mandibular first molar were virtually prepared by the reverse engineering software. Then dental design software was used to design digital full crown using the copy method. The mandibular movement trajectories under light and heavy bite force were separately used to guide virtual occlusal pre-adjustment. The three-dimensional deviations (mean deviations and root mean square) between the lingual surface of the left maxillary central incisor or the occlusal surface of the left mandibular first molar and that of the natural tooth before preparation were calculated (light bite force group and heavy bite force group), and the differences between the two groups were compared by the paired t-test. Results: Under the two kinds of bite force, the three-dimensional displacements of the markers in the ICP were (0.217±0.135), (0.210±0.133) and (0.237±0.101) mm, respectively; the sagittal projection of the three-dimensional displacements of the markers in the protrusive edge-to-edge position were (0.204±0.133), (0.288±0.148) and (0.292±0.136) mm, respectively; the coronal projection of the three-dimensional displacements of the mesial buccal cusp tips of the bilateral first molars in the lateral edge-to-edge position were (0.254±0.140) and (0.295±0.190) mm, respectively. The differences between the above displacements and 0 were statistically significant (P<0.05). The results of occlusal pre-adjustment showed that the mean deviations of the lingual surface of the left maxillary central incisor in the light and heavy bite force groups were (0.215±0.036) and (0.195±0.041) mm (t=3.95, P=0.004), respectively. The mean deviations of the occlusal surface of the left mandibular first molar were (0.144±0.084) and (0.100±0.096) mm (t=0.84, P=0.036), respectively. Conclusions: Both the light and heavy bite force have an influence on the mandibular movement trajectories. Virtual occlusal pre-adjustment of prostheses with mandibular movement trajectories under heavy bite force can obtain morphology of lingual or occlusal surfaces closer to the natural teeth before preparation.