RESUMO
INTRODUCTION: The aim of this study was to evaluate the effects of a fixed functional appliance (Forsus Fatigue Resistant Device; 3M Unitek, Monrovia, Calif) on the mandible with 3-dimensional finite element stress analysis. METHODS: A 3-dimensional finite element model of the mandible was constructed from the images generated by cone-beam computed tomography of a patient undergoing fixed orthodontic treatment. The changes were studied with the finite element method, in the form of highest von Mises stress and maximum principal stress regions. RESULTS: More areas of stress were seen in the model of the mandible with the Forsus compared with the model of the mandible in the resting stage. CONCLUSIONS: This fixed functional appliance studied by finite element model analysis caused increases in the maximum principal stress and the von Mises stress in both the cortical bone and the condylar region of the mandible by more than 2 times.
Assuntos
Análise de Elementos Finitos , Mandíbula/fisiopatologia , Desenho de Aparelho Ortodôntico , Aparelhos Ortodônticos Funcionais , Adolescente , Fenômenos Biomecânicos , Força de Mordida , Tomografia Computadorizada de Feixe Cônico/métodos , Feminino , Humanos , Processamento de Imagem Assistida por Computador/métodos , Imageamento Tridimensional/métodos , Má Oclusão Classe III de Angle/terapia , Côndilo Mandibular/fisiopatologia , Músculo Masseter/fisiopatologia , Modelos Biológicos , Contração Muscular/fisiologia , Músculos Pterigoides/fisiopatologia , Retrognatismo/terapia , Estresse Mecânico , Músculo Temporal/fisiopatologia , Dente/fisiopatologiaRESUMO
The purpose of this study was to investigate the feasibility of using a new three-dimensional ultrasound system to perform fetal echocardiographic examination in real time. The device consisted of a Philips Sonos 7500 (Andover, MA) ultrasound system and a 4 MHz, 4X matrix transducer. The study was approved by the Institutional Review Board and was performed with the informed consent of the mother. The study population consisted of 12 singleton fetuses with gestational ages of 16-37 weeks. Of these, ten fetuses had normal cardiac anatomy, one had complete atrioventricular septal defect, and the other a thickened tricuspid valve. The system allowed comprehensive visualization of fetal cardiac anatomy and color Doppler flow unattainable by two-dimensional approaches. This preliminary investigation suggests that live three-dimensional fetal echocardiography could be a significant tool for prenatal diagnosis and assessment of congenital heart disease in the human fetus.