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
Multiloop Edgewise Archwire Technique es una técnica desarrollada en los años 60 por Young H. Kim, la cual ha tenido un fuerte desarrollo en los países de Asia, especialmente Japón y Corea, por el Prof. Sadao Sato de la Universidad de Kanagawa, Japón. En la experiencia de la filosofía MEAW se ha dado particular importancia al tratamiento no quirúrgico de clases III y mordidas abiertas esqueletales. La discrepancia posterior (CP), concepto nuevo para la ortodoncia occidental, es considerada para determinar la remoción temprana de los terceros molares debido a su importancia como factor coadyuvante en la recidiva de los tratamientos de ortodoncia, especialmente el apiñamiento incisivo y en particular en la orientación del Dr. Sato, debido a su importancia en el desarrollo de la DP, que como se ha mencionado, es un factor etiopatogénico en el desarrollo de las maloclusiones esqueletales y mordidas abiertas antes, durante y postratamiento de ortodoncia.