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1.
PLoS One ; 19(8): e0308739, 2024.
Article in English | MEDLINE | ID: mdl-39159186

ABSTRACT

BACKGROUND: Micro-osteoperforation is a minimally invasive technique aimed at accelerating tooth movement. The goal of this novel experimental study was to assess tooth movement and stress distribution produced by the force of orthodontic movement on the tooth structure, periodontal ligament, and maxillary bone structure, with and without micro-osteoperforation, using the finite element method. MATERIALS AND METHODS: Cone-beam computed tomography was used to obtain a virtual model of the maxilla and simulate the extraction of right and left first premolars. Three micro-osteoperforations (1.5 x 5 mm) were made in the hemiarch on the distal and mesial surfaces of upper canines, according to the power tip geometry of the Propel device (Propel Orthodontics, Ossining, New York, USA). An isotropic model of the maxilla was fabricated according to the finite element method by insertion of mechanical properties of the tooth structures, with orthodontic force (1.5 N) simulation in the distal movement on the upper canine of a hemiarch. RESULTS: Initial movement was larger when micro-osteoperforations were performed on the dental crown (24%) and on the periodontal ligament (29%). In addition, stress distribution was higher on the bone structure (31%) when micro-osteoperforations were used. CONCLUSIONS: Micro-osteoperforations considerably increased the movement of both the dental crown and periodontal ligament, which highlights their importance in the improvement of orthodontic movement, as well as in stress distribution across the bone structure. Important stress absorption regions were identified within micro-osteoperforations.


Subject(s)
Finite Element Analysis , Periodontal Ligament , Tooth Movement Techniques , Tooth Movement Techniques/methods , Humans , Periodontal Ligament/physiology , Maxilla/physiology , Stress, Mechanical , Cone-Beam Computed Tomography/methods , Biomechanical Phenomena
2.
J Appl Biomech ; 30(3): 483-90, 2014 Jun.
Article in English | MEDLINE | ID: mdl-24603558

ABSTRACT

The intensity of Pilates exercises is almost exclusively based on experience. Therefore, knowing the precise amount of effort that is exerted during exercises could be useful for professionals conducting exercise assessments and for future research using inverse dynamics (ID) analyses. The reformer is an apparatus that contains a carriage on rails to which resistance is applied via springs attached to the carriage. Subjects apply force to a footbar to displace the carriage, but the magnitude and direction of this force are unknown and need to be quantified if the ID approach is to be used. This study aimed to develop and describe a device built with commercial load cells attached to the reformer's footbar, with the device capable of measuring the direction and magnitude of the force exerted on the reformer's footbar, and to compare the force found using the device with the force estimated using the springs' parameters. To illustrate the device's use, one volunteer performed footwork exercises at different speeds and with different foot support positions and loads. External force estimated by the springs' level of deformation was significantly different (P < .001) from the magnitude of force acquired using the device, showing that the estimation is imprecise.


Subject(s)
Ergometry/instrumentation , Exercise/physiology , Foot/physiology , Manometry/instrumentation , Transducers , Equipment Design , Equipment Failure Analysis , Ergometry/methods , Female , Humans , Manometry/methods , Pressure , Reproducibility of Results , Sensitivity and Specificity , Stress, Mechanical
3.
Motriz rev. educ. fís. (Impr.) ; 19(2): 523-531, abr.-jun. 2013. ilus, graf
Article in Portuguese | LILACS | ID: lil-678327

ABSTRACT

Durante exercícios realizados em máquinas de musculação, a força de atrito (FA) entre seus componentes mecânicos pode influenciar na magnitude da sobrecarga oferecida pela máquina para o praticante do exercício. No entanto, pouco se sabe sobre como medir esse atrito e qual seu real efeito. Assim, os objetivos deste estudo foram (i) descrever uma técnica para medição da FA em máquinas de musculação, e (ii) exemplificar a técnica quantificando a FA de uma máquina de musculação durante exercício em diferentes velocidades e cargas. Foram utilizados diagramas de corpo livre, equações da mecânica clássica além da medição dos ângulos articulares com eletrogoniômetro, e da força aplicada ao cabo de aço com célula de carga, para estimar a força de atrito. Para testar a metodologia, um indivíduo realizou repetições do exercício variando cargas e velocidade de execução. As cargas avaliadas foram 3kg, 6 kg e 9 kg; e as velocidades foram 30º/s, 60º/se 120º/s. A FA, expressa em percentual da carga, mostrou-se crescente com o incremento de velocidade e decrescente com o aumento da carga. Resultados em torno 40% obtidos para a menor carga e maior velocidade sugerem que a força de atrito deve ser um fator levado em consideração na escolha e manutenção de equipamentos de musculação.


During exercises performed in weight training machines, the friction force (FF) between its mechanical components can influence the magnitude of the overload offered by the machine on force of the exercise. However, little is known about how to measure this friction and what its real effect. Thus the objectives of this study were (i) describe a technique for measuring FF in weight training machines, and (ii) exemplify the technique, by quantifying the FF of the weight training machine at different exercise speeds and loads. For this, a subject performed repetitions of the exercise in different loads and speeds. The loads evaluated were 3 kg, 6 kg and 9 kg; and the speeds were 30°/s, 60°/s and 120°/s. The FF, normalized by selected load, increased significantly with the increasing of the speed and decreased with increasing of the load. Results for friction force around 40% found for highest speed and lowest load show that take the FF in count it's an important factor to consider during muscle equipment choice and maintaining.


Subject(s)
Biomechanical Phenomena , Friction , Sports Equipment
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