ABSTRACT
OBJECTIVE@#To investigate the stress distribution to the mandible, with and without impacted third molars (IM3s) at various orientations, resulting from a 2000-Newton impact force either from the anterior midline or from the body of the mandible.@*MATERIALS AND METHODS@#A 3D mandibular virtual model from a healthy dentate patient was created and the mechanical properties of the mandible were categorized to 9 levels based on the Hounsfield unit measured from computed tomography (CT) images. Von Mises stress distributions to the mandibular angle and condylar areas from static impact forces (Load I-front blow and Load II left blow) were evaluated using finite element analysis (FEA). Six groups with IM3 were included: full horizontal bony, full vertical bony, full 450 mesioangular bony, partial horizontal bony, partial vertical, and partial 450 mesioangular bony impaction, and a baseline group with no third molars.@*RESULTS@#Von Mises stresses in the condyle and angle areas were higher for partially than for fully impacted third molars under both loading conditions, with partial horizontal IM3 showing the highest fracture risk. Stresses were higher on the contralateral than on the ipsilateral side. Under Load II, the angle area had the highest stress for various orientations of IM3s. The condylar region had the highest stress when IM3s were absent.@*CONCLUSIONS@#High-impact forces are more likely to cause condylar rather than angular fracture when IM3s are missing. The risk of mandibular fracture is higher for partially than fully impacted third molars, with the angulation of impaction having little effect on facture risk.
Subject(s)
Adult , Female , Humans , Algorithms , Biomechanical Phenomena , Computer Simulation , Dental Stress Analysis , Elastic Modulus , Finite Element Analysis , Imaging, Three-Dimensional , Mandible/physiopathology , Mandibular Fractures/physiopathology , Models, Biological , Molar, Third/physiopathology , Stress, Mechanical , Tomography, X-Ray ComputedABSTRACT
Analiza que la fractura de la mandíbula ocupa el segundo lugar en frecuencia de las fracturas del complejo maxilofacial. La incidencia de este tipo de lesiones es mayor en el sexo masculino y las edades pico de presentación corresponden a la segunda y tercera décadas de edad. Son varios los factores que determinan el tipo de fractura, destacándose entre los más importantes a la dirección de la fuerza aplicada además de la localización y desplazamiento de las estructuras de acuerdo a la fuerza aplicada. Las fracturas de acuerdo a su ubicación se clasifican en condíleas o subcondíleas, de coronoides, de la rama ascendente, angulares, corporales, sinfisarias, parasinfisarias y alveolares. El sitio de la fractura, características de la misma, estado dentario, edad del paciente y evolución de la consolidación son factores determinantes de la elección de la técnica a emplearse en su resolución (métodos abiertos o cerrados). El aspecto fundamental en el tratamiento de las fracturas mandibulares es la consecución de la correcta articulación dentaria. La utilización de miniplacas ha revolucionado el manejo de las fracturas mandibulares.
Subject(s)
Humans , Mandibular Fractures/classification , Mandibular Fractures/diagnosis , Mandibular Fractures/physiopathology , Mandibular Fractures/therapy , PatientsABSTRACT
O objetivo deste trabalho foi observar se o uso da fixaçäo interna rígida com microplacas em fraturas de colo de côndilo e ângulo de mandíbula, interfere no crescimento mandibular em coelhos jovens. Foram utilizados 35 coelhos machos da raça Nova Zelândia, divididos em 5 grupos, sendo o primeiro grupo de controle. No segundo apenas foi feito o deslocamento do periósteo. O terceiro grupo foi dividido em dois subgrupos, onde foram realizadas fraturas sem osteossíntese, no colo de côndilo e no ângulo de mandíbula. Fraturas nas mesmas regiöes, porém, utilizando-se a FIR com microplacas foram feitas no quarto grupo; no quinto grupo foram unicamente colocadas as microplacas no colo de côndilo. Os resultados encontrados mostram que näo existem diferenças estatisticamente significativas (teste de " t " de Student com nível de significância de 5 por cento) entre os grupos estudados