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.

Odontoma Compuesto: Diagnóstico y Tratamiente Reporte de Casos & Revisión de la Literatura / Compound Odontoma: Diagnosis and Treatment Therapeutic Measures. Case Reports & Literature Review

RESUMEN: Los odontomas son los tumores odontogénicos benignos más prevalentes. Estos están conformados por tejido dentario, epitelio odontogénico y tejido mesenquimático. Se dividen en dos subtipos: odontomas compuestos, que presentan tejidos dentarios normales, pero con una alteración en su conformación y tamaño, y odontomas complejos, que presentan tejidos dentarios bien formados, pero rodeados de tejido desorganizado. Se presentan tres casos de pacientes sexo femenino, quienes acuden para evaluación y tratamiento debido al hallazgo radiográfico de odontoma compuesto. En el caso nº 1 se realizó la desinclusión del diente impactado, la exodoncia del diente remanente, la exéresis del odontoma compuesto, la instalación de un implante dental en el alveolo de la zona intervenida y, finalmente, el posicionamiento de injerto óseo. En el caso nº 2 se realizó la exodoncia del diente temporal remanente y la exéreis del odontoma compuesto. Ambos casos evolucionaron de manera favorable sin complicaciones post operatorias. En el caso nº 3 se realizó la fenestración del diente 18 y la exéreis del odontoma compuesto que retenía su erupción. Todos los casos evolucionaron de manera favorable sin complicaciones post operatorias. Dada la prevalencia de esta patología, es necesario un adecuado conocimiento sobre ella y sus características, para realizar un adecuado diagnóstico y tratamiento. Existen distintas medidas terapéuticas respecto a la rehabilitación de una zona edéntula como resultado de la exéresis de estos tumores. Esto depende principalmente de la edad del paciente. Al ser requeridas medidas rehabilitadoras, un punto importante a considerar es la posibilidad de realizar todos los procedimientos quirúrgicos en un solo tiempo operatorio.

ABSTRACT: Odontomas are the most common benign odontogenic tumors and are composed of dental tissue, odontogenic epithelium and mesenchymal tissue. They are divided into two subtypes: Compound odontomas, which present normal tooth tissue, but an alteration in their conformation and size, and complex odontomas, which present well-formed tooth tissue, but are surrounded by disorganized tissue. A bibliographic review was performed by one operator in Pubmed and Epistemonikos. After filtering by title and abstract, only one systematic review was selected. We present two clinical cases of compound odontoma in female patients at the Military Hospital in Santiago. Patients were referred for evaluation and treatment due to the radiographic finding of compound odontoma. In case # 1, the impacted tooth was disincluded, the remaining temporal tooth was extracted, and excision of the compound odontoma carried out; subsequently a bone graft implant was placed in the remaining socket. In case # 2, the remaining temporal tooth was extracted and compound odontoma excised. After that, natural eruption of the corresponding permanent tooth is expected. In case # 3, tooth 1.8 fenestration and excision of compound odontoma was performed. In this case also, natural eruption of the corresponding permanent tooth is expected. Given the prevalence of this pathology, adequate knowledge of compound odontomas and their characteristics is necessary for proper diagnosis and treatment. There are different therapeutic measures for the rehabilitation of an edentulous area following excision of compound odontoma. This depends mainly on the age of the patient. When rehabilitation measures are required, an important aspect to consider for the patient, is the possibility of a single surgical event, as was done in case # 1.

Three-dimensional dental arch changes of patients submitted to orthodontic-surgical treatment for correction of Class II malocclusion

INTRODUCTION: This study assessed the three-dimensional changes in the dental arch of patients submitted to orthodontic-surgical treatment for correction of Class II malocclusions at three different periods. METHODS: Landmarks previously identified on upper and lower dental casts were digitized on a three-dimensional digitizer MicroScribe-3DX and stored in Excel worksheets in order to assess the width, length and depth of patient's dental arches. RESULTS: During orthodontic preparation, the maxillary and mandibular transverse dimensions measured at the premolar regions were increased and maintained throughout the follow-up period. Intercanine width was increased only in the upper arch during orthodontic preparation. Maxillary arch length was reduced during orthodontic finalization, only. Upper and lower arch depths were stable in the study periods. Differences between centroid and gingival changes suggested that upper and lower arch premolars buccaly proclined during the pre-surgical period. CONCLUSIONS: Maxillary and mandibular dental arches presented transverse expansion at premolar regions during preoperative orthodontic preparation, with a tendency towards buccal tipping. The transverse dimensions were not altered after surgery. No sagittal or vertical changes were observed during the follow-up periods. .

INTRODUÇÃO: esse estudo avaliou as alterações tridimensionais ocorridas na morfologia das arcadas dentárias de pacientes submetidos ao tratamento ortodôntico-cirúrgico para a correção da má oclusão de Classe II, em três períodos distintos: (T1) modelos iniciais, (T2) modelos pré-cirúrgicos imediatos (de 1 a 15 dias antes da cirurgia) e (T3) modelos pós-cirúrgicos (mínimo de 6 meses após a remoção do aparelho ortodôntico). MÉTODOS: pontos previamente demarcados em cada modelo foram digitalizados por meio do digitalizador tridimensional MicroScribe-3DX, cujas coordenadas, armazenadas em planilhas do programa Excel, deram origem a valores que possibilitaram a avaliação da largura, comprimento e profundidade das arcadas dentárias. RESULTADOS: durante o preparo ortodôntico, houve aumentos nas distâncias transversais superiores e inferiores medidas na região de pré-molares que se mantiveram no período total de acompanhamento. Apenas a distância intercaninos superior apresentou alterações de aumento durante o preparo ortodôntico, assim como a largura da arcada superior, que diminuiu durante a fase de finalização. A profundidade de ambas as arcadas manteve-se estável nas fases avaliadas. Diferenças entre as mudanças dos pontos centroide e gengival sugerem que os pré-molares superiores e inferiores inclinaram para vestibular durante o preparo ortodôntico pré-cirúrgico. CONCLUSÇÕES: conclui-se que as arcadas dentárias superiores e inferiores sofreram expansão transversal na região de pré-molares durante o preparo ortodôntico pré-cirúrgico, com tendência à inclinação vestibular de todos os dentes posteriores. Após a cirurgia, as dimensões transversais ...

Osteotomía sagital de rama mandibular con osteosíntesis en L invertido: estudio mecánico con fotoelasticidad / Sagittal split ramus osteotomy with L inverted osteosynthesis: A mechanical study with photoelasticity

El objetivo de esta investigación es identificar las tensiones presentes en tornillos de osteosíntesis utilizados en la fijación de la osteotomía sagital de rama mandibular (OSRM). Se utilizaron dos modelos de OSRM realizados con resina fotoelástica donde el grupo 1 presentaba una osteotomía basilar recta mientras que el grupo 2 presentaba una osteotomía basilar angulada; en ambos se utilizo el sistema de L invertido para la osteosíntesis con tornillos 2.0 de 13 mm de longitud. Posteriormente el sistema fue instalado en un pilar sobre la maquina Instrom, donde se aplico una carga vertical de 1 mm/minuto hasta conseguir el desplazamiento de 3 mm; el punto de carga estuvo en la fosa central del primer molar. La distribución de franjas mostro mayor tensión en el tornillo mas próximo de la osteotomía en ambos grupos; en el grupo 2 se produjo una diseminación de fuerzas levemente hacia la basilar y en el grupo 1 se mantuvo la diseminación a través de la línea oblicua. Se puede concluir que ambas osteotomías mandibulares son eficientes en la distribución de cargas y que no se observan diferencias cualitativas entre tornillos en términos de cantidad de diseminación de energía

The aim of this research was to analyzed the tension in osteosynthesis screw used for fixation of sagittal split ramus osteotomy (SSRS). Was used two model of SSRS made in photoelastic resin; in one of them was include a basilar osteotomy and the another one only SSRS without basilar osteotomy; for both system was used inverted L osteosynthesis with 13 mm screw of 2.0 system. Posteriorly, the hemimandible was installed in Instrom machine with a vertical load of 1 mm/min until the displacement of 3 mm; the load point was on first molar. The fringe distribution show more tension in the screw close to osteotomy in both groups; when SSRS was united to basilar osteotomy was produced a inferior distribution of force and in the SSRS without basilar osteotomy group was maintained a distribution into the oblique line. It's was conclude that both mandibular osteotomies was efficient in load distribution and was not observed important differences between screw related to distribution of load

Biomechanical in vitro evaluation of three stable internal fixation techniques used in sagittal osteotomy of the mandibular ramus: a study in sheep mandibles

Among the osteotomies performed in orthognathic surgery, the sagittal osteotomy of the mandibular ramus (SOMR) is the most common, allowing a great range of movements and stable internal fixation (SIF), therefore eliminating the need of maxillomandibular block in the postoperative period. OBJECTIVES: The purpose of this study was to evaluate the biomechanical resistance of three national systems used for SIF in SOMR in sheep mandibles. MATERIAL AND METHODS: The study was performed in 30 sheep hemi-mandibles randomly divided into 3 experimental groups, each containing 10 hemi-mandibles. The samples were measured to avoid discrepancies and then subjected to SOMR with 5-mm advancement. In group I, 2.0x12 mm screws were used for fixation, inserted in an inverted "L" pattern (inverted "L" group). In group II, fixation was performed with two 2.0x12 mm screws, positioned in a linear pattern and a 4-hole straight miniplate and four 2.0x6.0 mm monocortical screws (hybrid group). In group III, fixation was performed with two 4-hole straight miniplates and eight 2.0x6.0 mm monocortical screws (mini plate group). All materials used for SIF were supplied by Osteosin - SIN. The hemimandibles were subjected to vertical linear load test by Kratos K2000MP mechanical testing unit for loading registration and displacement. RESULTS: All groups showed similar resistance during mechanical test for loading and displacement, with no statistically significant differences between groups according to analysis of variance. CONCLUSION: These results indicate that the three techniques of fixation are equally effective for clinical fixation of SOMR.

Evaluación de la anatomía mandibular relacionada con la osteotomía sagital de la rama / Evaluation of mandibular anatomy related to sagittal split ramus osteotomy

La osteotomía sagital de la rama mandibular (SSRO) es una de las técnicas quirúrgicas más frecuentes para corregir las deformidades de la mandíbula. Con el fin de prevenir problemas anatómicos y quirúrgicos, los cirujanos requieren una mayor investigación sobre las estructuras anatómicas relacionadas con la SSRO. El objetivo de este estudio fue investigar las posiciones de la antilingula (AL), la entrada al nervio alveolar inferior (NAI) en la mandíbula y otros puntos de referencia anatómicos en relación con la língula mandibular (L). Fueron estudiadas 70 hemimandíbulas secas. La AL y los demás puntos de referencia y, la posición correspondiente de la L se marcaron en la cara medial y lateral de la rama mandibular respectivamente. Fueron medidas las distancias de la AL, NAI y L en los planos anterior-posterior y superior-inferior con un caliper, y se estableció su relación geométrica. Los resultados mostraron que la AL era perceptible en el 100 por ciento de las caras laterales mandibulares. La mayoría de las ALs se encuentran anterior a la L, con una distancia media de 0,66+/-2,43mm y 0,92+/-2,56 mm y, 4,23+/-2,97 mm y 3,62 +/- 3,14 mm superior a ella (lados derecho-izquierdo respectivamente) (ambos con un valor de p <0,001). Valores similares se observaron en relación con el NAI. No se encontraron diferencias significativas entre los lados derecho e izquierdo, para la mayoría de los parámetros. Los parámetros estudiados pueden asistir a los cirujanos maxilofaciales a determinar la proximidad anatómica del NAI, y reducir al mínimo el riesgo de dañar el nervio y vasos sanguíneos. No recomendamos el uso de la AL como única referencia anatómica cuando se realiza un procedimiento de SSRO.

Sagittal split ramus osteotomy (SSRO) of the mandible is one of the most common surgical techniques to correct mandibular deformities. In order to prevent many surgical anatomical problems, surgeons have found that further investigation of the anatomical structures related to SSRO is needed. This study aims to investigate positions of the antilingula (AL), inferior alveolar nerve (IAN) and other anatomic landmarks in relation to the lingula of dried mandibles. 70 Chilean dried hemimandibles were studied. The AL, others landmarks and the corresponding position of the L were marked on the internal and external aspect of the mandibular ramus respectively. The distances from the AL, IAN and L were measured in the anterior­posterior and the superior­inferior planes using a digital caliper and geometric relationship was established. The results showed the AL was discernible in 100 percent of lateral mandibular rami studied. The most of the AL was found anteriorly to the L with a mean distance of 0.66+/-2.43mm and 0.92+/-2.56mm, and 4.23 +/- 2.97mm and 3.62+/-3.14mm superiorly (right-left sides respectively) (both with p value <0.001). Similar values were seen in relation with IAN. No significant differences were found between the right and left sides, for the majority of parameters. The studied parameters will assist clinicians to determine the anatomical proximity to the IAN, and, minimize the risk of damaging nerver and vessels. We do not recommend the use of antilingula as only anatomical landmark when performing a SSRO procedure.