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1.
Orthod Craniofac Res ; 26(4): 531-538, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36807468

RESUMO

INTRODUCTION: The presented study investigates differences in the biomechanics of straight and mushroom fixed lingual appliances when implementing coil springs and stops for anterior arch expansion. MATERIALS AND METHODS: An in vitro orthodontic simulator was used to measure three-dimensional forces and moments on each tooth of a simulated maxillary arch. Mushroom and straight archwire forms of 0.016″ NiTi round archwire were considered, using 0.010″ × 0.030″ NiTi open coils and 0.016″-0.018″ archwire stops (n = 44 per group). Teeth in the anterior dental arch were moved from a neutral to crowded position to replicate anterior crowding of central and lateral incisors. Forces and moments of interest for lateral incisors and first premolars were compared using repeated measures mixed multivariate analysis of variance (α = 0.05). RESULTS: Three comparisons between straight versus mushroom archwires and two comparisons of coil springs vs. stops were not statistically significant. Overall, it was found that the use of a straight lingual archwire produced larger differences in forces and moments between using stops and coil springs than when using a mushroom archwire. Using stops produced larger forces and moments for both types of archwires as compared to using coil springs. The largest expansion forces were produced using straight archwires with stops, exceeding 3.0 N of force. Straight archwires with coil springs produced the lowest expansion forces on lateral incisors, just exceeding 1.5 N. CONCLUSIONS: The findings of this study have elucidated significant differences in the biomechanics of transverse arch expansion using straight or mushroom fixed lingual appliances with coil springs or stops.


Assuntos
Má Oclusão , Braquetes Ortodônticos , Humanos , Fenômenos Biomecânicos , Desenho de Aparelho Ortodôntico , Fios Ortodônticos , Aparelhos Ortodônticos Fixos , Titânio , Técnicas de Movimentação Dentária/métodos
2.
Sensors (Basel) ; 23(1)2022 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-36616932

RESUMO

Hockey skating objective assessment can help coaches detect players' performance drop early and avoid fatigue-induced injuries. This study aimed to calculate and experimentally validate the 3D angles of lower limb joints of hockey skaters obtained by inertial measurement units and explore the effectiveness of the on-ice distinctive features measured using these wearable sensors in differentiating low- and high-calibre skaters. Twelve able-bodied individuals, six high-calibre and six low-calibre skaters, were recruited to skate forward on a synthetic ice surface. Five IMUs were placed on their dominant leg and pelvis. The 3D lower-limb joint angles were obtained by IMUs and experimentally validated against those obtained by a motion capture system with a maximum root mean square error of 5 deg. Additionally, among twelve joint angle-based distinctive features identified in other on-ice studies, only three were significantly different (p-value < 0.05) between high- and low-calibre skaters in this synthetic ice experiment. This study thus indicated that skating on synthetic ice alters the skating patterns such that the on-ice distinctive features can no longer differentiate between low- and high-calibre skating joint angles. This wearable technology has the potential to help skating coaches keep track of the players' progress by assessing the skaters' performance, wheresoever.


Assuntos
Hóquei , Dispositivos Eletrônicos Vestíveis , Humanos , Fenômenos Biomecânicos , Gelo , Hóquei/lesões , Extremidade Inferior
3.
Sensors (Basel) ; 22(10)2022 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-35632311

RESUMO

A commonly cited reason for the high abandonment rate of myoelectric prostheses is a lack of grip force sensory feedback. Researchers have attempted to restore grip force sensory feedback by stimulating the residual limb's skin surface in response to the prosthetic hand's measured grip force. Recent work has focused on restoring natural feedback to the missing digits directly through invasive surgical procedures. However, the functional benefit of utilizing somatotopically matching feedback has not been evaluated. In this paper, we propose an experimental protocol centered on a fragile object grasp and lift task using a sensorized myoelectric prosthesis to evaluate sensory feedback techniques. We formalized a suite of outcome measures related to task success, timing, and strategy. A pilot study (n = 3) evaluating the effect of utilizing a somatotopically accurate feedback stimulation location in able-bodied participants was conducted to evaluate the feasibility of the standardized platform, and to inform future studies on the role of feedback stimulation location in prosthesis use. Large between-participant effect sizes were observed in all outcome measures, indicating that the feedback location likely plays a role in myoelectric prosthesis performance. The success rate decreased, and task timing and task focus metrics increased, when using somatotopically-matched feedback compared to non-somatotopically-matched feedback. These results were used to conduct a power analysis, revealing that a sample size of n = 8 would be sufficient to achieve significance in all outcome measures.


Assuntos
Membros Artificiais , Retroalimentação , Mãos , Humanos , Projetos Piloto , Desenho de Prótese
4.
J Theor Biol ; 495: 110251, 2020 06 21.
Artigo em Inglês | MEDLINE | ID: mdl-32199857

RESUMO

Muscle is typically modelled using a lump sum idealization, scaling a single fascicle to represent the entire muscle. However, fascicles within a muscle have unique orientations, which could result in forces exerted not only in the axis running along the tendon, but also the two perpendicular axes, describing the muscle's width and depth. The purpose of this research was to develop a geometric-based model of the soleus, medial gastrocnemius, and lateral gastrocnemius as distributed force systems which can predict three-dimensional forces. Measurements were taken from the triceps surae in two human cadavers (80 and 85 years old). These models predicted muscle volumes and ankle plantar flexor moments that were realistic considering the age of the cadavers. Small differences were observed in calcaneal tendon force and moment for the distributed force models compared to modelling muscle force using a lump sum idealization. The major finding of the distributed force models was that forces were present in the axes corresponding to the muscle's length, width, and depth. The forces in the width and depth axes may be relevant for evaluating how muscle shape changes during contraction, as well as to investigate stress-strain patterns along the muscle's proximal and distal aponeuroses.


Assuntos
Tendão do Calcâneo , Modelos Biológicos , Contração Muscular , Músculo Esquelético , Idoso de 80 Anos ou mais , Tornozelo/fisiologia , Fenômenos Biomecânicos , Humanos , Perna (Membro) , Músculo Esquelético/fisiologia , Placa Plantar/fisiologia
5.
New Phytol ; 218(2): 835-846, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29453936

RESUMO

Rapidly determining root growth patterns is biologically important and technically challenging. Current methods focus on direct observation of roots and require destructive excavations or time-consuming root tracing. We developed a novel methodology based on analyzing soil particle displacement, rather than direct observation of roots. This inferred root growth method uses digital image correlation (DIC) analysis, an established and high-throughput method used in many engineering and science disciplines. By applying DIC analyses to repeated images of plants grown in clear window boxes, we produced visually intuitive and quantifiable strain maps, indicating the magnitude and direction of soil movement. From this, we could infer root growth and rapidly quantify root system metrics. Strain measures were closely associated with the spatial distribution of roots and correlated with root length measured using conventional approaches. The method also allowed for the detection of root proliferation in nutrient-enriched soil patches, indicating its suitability for quantifying biological patterns. This novel application of DIC in root biology is effective, scalable, low cost, flexible and complementary to existing technologies. This method offers a new tool for answering questions in plant biology and will be particularly useful in studies involving temporal dynamics of root processes.


Assuntos
Processamento de Imagem Assistida por Computador/métodos , Raízes de Plantas/anatomia & histologia , Raízes de Plantas/crescimento & desenvolvimento , Helianthus/anatomia & histologia , Helianthus/crescimento & desenvolvimento , Solo
6.
Eur J Orthod ; 39(6): 665-672, 2017 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-28430887

RESUMO

INTRODUCTION: An Orthodontic SIMulator (OSIM) was used to investigate the propagation of forces and moments around a simulated archform for a gingival displaced canine and lingual displaced lateral incisor using fixed lingual orthodontic appliances. METHODS: In-Ovation L self-ligating lingual brackets were bonded to anatomically shaped teeth on the OSIM, and the teeth were positioned such that a G4 NiTi 0.016" large maxillary mushroom archwire could be ligated in passive position. Each trial consisted of two movements: a 3mm lingual displacement of the 1-2 lateral incisor at 0.2 mm increments, and a 1.5 mm gingival displacement of the 2-3 canine at 0.15 mm increments (n = 50). Anterior brackets were repositioned to accommodate G4 NiTi 0.016" universal straight archwires (n = 50). Tests were completed at 37°C, and force and moment data in all directions was collected for each tooth around the arch at all increments. RESULTS: In general, the straight archwire produced significantly larger forces and moments at the centre of resistance for teeth of interest than did mushroom archwires. Specifically, the straight archwire produced 2.62 N and 3.81 N more force in the direction of tooth movement on the tooth being moved for a gingival displaced canine and lingual displaced lateral incisor, respectively, as compared to mushroom archwires. CONCLUSIONS: Results from this study suggest that mushroom archwires may provide better mechanics for movement of teeth in the anterior segment when using a round archwire; however, only biomechanical data was considered in this study and there are many factors that need to be considered in treatment planning.


Assuntos
Má Oclusão/terapia , Maxila/fisiopatologia , Braquetes Ortodônticos , Fios Ortodônticos , Técnicas de Movimentação Dentária/instrumentação , Ligas Dentárias , Análise do Estresse Dentário/métodos , Humanos , Incisivo/fisiopatologia , Níquel , Desenho de Aparelho Ortodôntico , Aparelhos Ortodônticos Fixos , Estresse Mecânico , Titânio , Técnicas de Movimentação Dentária/métodos
7.
Am J Orthod Dentofacial Orthop ; 149(1): 67-75, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-26718380

RESUMO

INTRODUCTION: Our objective was to identify and evaluate the accuracy and precision (intrarater and interrater reliabilities) of various anatomic landmarks for use in 3-dimensional maxillary and mandibular regional superimpositions. METHODS: We used cone-beam computed tomography reconstructions of 10 human dried skulls to locate 10 landmarks in the maxilla and the mandible. Precision and accuracy were assessed with intrarater and interrater readings. Three examiners located these landmarks in the cone-beam computed tomography images 3 times with readings scheduled at 1-week intervals. Three-dimensional coordinates were determined (x, y, and z coordinates), and the intraclass correlation coefficient was computed to determine intrarater and interrater reliabilities, as well as the mean error difference and confidence intervals for each measurement. RESULTS: Bilateral mental foramina, bilateral infraorbital foramina, anterior nasal spine, incisive canal, and nasion showed the highest precision and accuracy in both intrarater and interrater reliabilities. Subspinale and bilateral lingulae had the lowest precision and accuracy in both intrarater and interrater reliabilities. CONCLUSIONS: When choosing the most accurate and precise landmarks for 3-dimensional cephalometric analysis or plane-derived maxillary and mandibular superimpositions, bilateral mental and infraorbital foramina, landmarks in the anterior region of the maxilla, and nasion appeared to be the best options of the analyzed landmarks. Caution is needed when using subspinale and bilateral lingulae because of their higher mean errors in location.


Assuntos
Pontos de Referência Anatômicos/diagnóstico por imagem , Tomografia Computadorizada de Feixe Cônico/estatística & dados numéricos , Imageamento Tridimensional/estatística & dados numéricos , Mandíbula/diagnóstico por imagem , Maxila/diagnóstico por imagem , Cefalometria/estatística & dados numéricos , Marcadores Fiduciais , Osso Frontal/diagnóstico por imagem , Humanos , Processamento de Imagem Assistida por Computador/estatística & dados numéricos , Osso Nasal/diagnóstico por imagem , Variações Dependentes do Observador , Órbita/diagnóstico por imagem , Reprodutibilidade dos Testes
8.
Am J Orthod Dentofacial Orthop ; 148(3): 431-9, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26321341

RESUMO

INTRODUCTION: This in-vitro study presents the development and validation of an artificial tooth-periodontal ligament-bone complex (ATPBC) and comparison of its behavior with that of rigid dowels during third-order torque simulation. METHODS: ATPBCs were coupled using a 1:1 mixture of room-temperature vulcanization silicone and gasket sealant to act as a periodontal ligament simulant (PDLS). PDLS thicknesses ranging from 0.2 to 0.7 mm, in increments of 0.1 mm (n = 5 for each thickness), were tested using a linear crown displacement procedure. A suitable PDLS thickness was selected for use in third-order torque simulations to compare ATPBC (n = 29) and rigid (n = 24) dowel behavior. Their results were compared for archwire rotations up to 20° for both loading and unloading curves with repeated-measures analysis of variance. RESULTS: When used in third-order torque simulations, the ATPBC dowels with a 0.5-mm PDLS thickness showed a statistically significant difference from rigid dowels (P = 0.020), with a 95% confidence interval (0.254, 2.897 N·mm) and a mean difference of 1.575 N·mm. CONCLUSIONS: Inclusion of a PDLS in an ATPBC resulted in a statistical difference when compared with rigid dowels; however, the region where behavior differed was at low angles of archwire rotation, and the resultant torque was arguably outside a clinically relevant range.


Assuntos
Processo Alveolar/fisiologia , Incisivo/fisiologia , Aparelhos Ortodônticos , Ligamento Periodontal/fisiologia , Técnicas de Movimentação Dentária/instrumentação , Processo Alveolar/anatomia & histologia , Fenômenos Biomecânicos , Complacência (Medida de Distensibilidade) , Ligas Dentárias/química , Humanos , Incisivo/anatomia & histologia , Metacrilatos/química , Modelos Anatômicos , Braquetes Ortodônticos , Fios Ortodônticos , Ligamento Periodontal/anatomia & histologia , Polimetil Metacrilato/química , Distribuição Aleatória , Reprodutibilidade dos Testes , Rotação , Silicones/química , Aço Inoxidável/química , Estresse Mecânico , Alvéolo Dental/anatomia & histologia , Alvéolo Dental/fisiologia , Dente Artificial , Torque
9.
Sports Biomech ; 14(1): 122-38, 2015 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25895990

RESUMO

Hip extensor strategy, specifically relative contribution of gluteus maximus versus hamstrings, will influence quadriceps effort required during squat exercise, as hamstrings and quadriceps co-contract at the knee. This research examined the effects of hip extensor strategy on quadriceps relative muscular effort (RME) during barbell squat. Inverse dynamics-based torque-driven musculoskeletal models were developed to account for hamstrings co-contraction. Net joint moments were calculated using 3D motion analysis and force platform data. Hamstrings co-contraction was modelled under two assumptions: (1) equivalent gluteus maximus and hamstrings activation (Model 1) and (2) preferential gluteus maximus activation (Model 2). Quadriceps RME, the ratio of quadriceps moment to maximum knee extensor strength, was determined using inverse dynamics only, Model 1 and Model 2. Quadriceps RME was greater in both Models 1 and 2 than inverse dynamics only at barbell loads of 50-90% one repetition maximum. The highest quadriceps RMEs were 120 ± 36% and 87 ± 28% in Models 1 and 2, respectively, which suggests that barbell squats are only feasible using the Model 2 strategy prioritising gluteus maximus versus hamstrings activation. These results indicate that developing strength in both gluteus maximus and quadriceps is essential for lifting heavy loads in squat exercise.


Assuntos
Exercício Físico/fisiologia , Articulação do Quadril/fisiologia , Músculo Esquelético/fisiologia , Músculo Quadríceps/fisiologia , Adulto , Fenômenos Biomecânicos , Feminino , Humanos , Contração Muscular , Levantamento de Peso , Adulto Jovem
10.
Am J Orthod Dentofacial Orthop ; 146(6): 758-64, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-25432257

RESUMO

INTRODUCTION: Two-dimensional maxillary superimposition techniques have been routinely used in clinical practice, but a 3-dimensional plane has yet to be introduced and validated. The purposes of this study were to propose a new plane for regional superimposition of the maxillary complex and then to validate it through clinical data. METHODS: Pretreatment and posttreatment palatal expansion records were used. The magnitudes of the transverse expansion at the levels of the first premolars and the first molars were assessed using the proposed superimposition plane and then were compared with the gold standard plaster model measurements. Descriptive statistics and agreement testing were performed to compare the methods. RESULTS: When comparing the superimposition and plaster measurement methods, the mean errors for intermolar and interpremolar distances were 0.57 and 0.59 mm, respectively. Both the intraclass correlation coefficient and the Bland-Altman plot demonstrated high agreement between the 2 methods (intraclass correlation coefficient greater than 0.9). CONCLUSIONS: The proposed maxillary superimposition plane yields clinically suitable results when compared with the gold standard technique, with a mean error of less than 0.6 mm for typical intra-arch measurements. This new landmark-derived maxillary plane for superimposition is a promising tool for evaluating maxillary dentoalveolar changes after treatment.


Assuntos
Cefalometria/estatística & dados numéricos , Processamento de Imagem Assistida por Computador/estatística & dados numéricos , Imageamento Tridimensional/estatística & dados numéricos , Maxila/diagnóstico por imagem , Nariz/diagnóstico por imagem , Pontos de Referência Anatômicos/diagnóstico por imagem , Dente Pré-Molar/diagnóstico por imagem , Criança , Tomografia Computadorizada de Feixe Cônico/estatística & dados numéricos , Arco Dental/diagnóstico por imagem , Feminino , Humanos , Masculino , Modelos Dentários , Dente Molar/diagnóstico por imagem , Técnica de Expansão Palatina , Reprodutibilidade dos Testes , Estudos Retrospectivos
11.
Eur J Orthod ; 36(4): 381-8, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-22015820

RESUMO

Orthodontic torque expression is the result of axial rotation of rectangular archwires within a rectangular bracket slot. This study investigates the effect of bracket material on torque expression. Torque exerted by a rotating archwire on each bracket will be measured as well as the relative deformation of each bracket slot. A total of 60 tests were performed where archwires were rotated within a bracket slot to produce torque within a bracket. Thirty Ormco Orthos Ti and 30 Orthos SS were compared to investigate the effect of torque on bracket material. Each bracket was mounted on a six-axis load cell that measured forces and moments in all directions. The archwire was rotated from an initial angle of 0 degree in 3 degrees increments to maximum angle of 51 degrees and then returned to the initial position. An overhead camera took images at each 3 degrees increment. The bracket images were post-processed using a digital image correlation technique to measure the relative deformation of each bracket slot. The maximum torque expressed at 51 degrees was 99.8 Nmm and 93.0 Nmm for Orthos Ti and Orthos SS, respectively. Total plastic deformation measured at 0 degrees post-torquing of the Orthos SS was 0.038 mm compared to 0.013 mm for Orthos Ti. The Orthos Ti brackets plastically deformed less than the Orthos SS brackets after torquing. The Orthos SS bracket plastic deformation was 2.8 times greater than that of Orthos Ti brackets. The Orthos Ti brackets expressed more torque than the stainless steel brackets but exhibited substantial variation.


Assuntos
Materiais Dentários/química , Desenho de Aparelho Ortodôntico , Braquetes Ortodônticos , Aço Inoxidável/química , Titânio/química , Humanos , Processamento de Imagem Assistida por Computador/métodos , Teste de Materiais , Fios Ortodônticos , Fotografação/métodos , Rotação , Estresse Mecânico , Propriedades de Superfície , Torque
12.
J Appl Biomech ; 30(1): 179-83, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24676526

RESUMO

Sit-to-stand transfer is a common prerequisite for many daily tasks. Literature often assumes symmetric behavior across the left and right side. Although this assumption of bilateral symmetry is prominent, few studies have validated this supposition. This pilot study uniquely quantifies peak joint moments and ground reaction forces (GRFs), using a Euclidian norm approach, to evaluate bilateral symmetry and its relation to lower limb motor-dominance during sit to stand in ten healthy males. Peak joint moments and GRFs were determined using a motion capture system and inverse dynamics. This analysis included joint moment contributions from all three body planes (sagittal, coronal, and axial) as well as vertical and shearing GRFs. A paired, one-tailed t test was used, suggesting asymmetrical joint moment development in all three lower extremity joints as well as GRFs (P < .05). Furthermore, using an unpaired two-tailed t test, asymmetry developed during these movements does not appear to be predictable by participants' lower limb motor-dominance (P < .025). Consequently, when evaluating sit-to-stand it is suggested the effects of asymmetry be considered in the interpretation of data. The absence of a relationship between dominance and asymmetry prevents the suggestion that one side can be tested to infer behavior of the contralateral.


Assuntos
Lateralidade Funcional/fisiologia , Articulações/fisiologia , Perna (Membro)/fisiologia , Movimento/fisiologia , Contração Muscular/fisiologia , Músculo Esquelético/fisiologia , Postura/fisiologia , Adulto , Simulação por Computador , Desenho de Equipamento , Análise de Falha de Equipamento , Humanos , Masculino , Modelos Biológicos , Projetos Piloto , Estresse Mecânico , Torque
13.
J Orthod ; 41(3): 188-200, 2014 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-24596162

RESUMO

OBJECTIVE: Torque is applied to orthodontic brackets in order to alter the buccal-lingual angulation of a tooth. One factor that can affect torque is the ligation mode used to retain the archwire in the bracket slot. The objective of this study was to investigate the effects of stainless steel ligation on torque expression and bracket deformation. METHODS: This study utilized 60 upper right central incisor Damon Q brackets and 60 Ormco Orthos Twin brackets. The brackets used in this study were subdivided into four groups: (1) Damon Q ligated with SS ligature; (2) Damon Q with the sliding bracket door; (3) Orthos Twin bracket ligated with SS wire; and (4) Orthos Twin ligated with elastic ties. All brackets were tested using an orthodontic torque simulating device that applied archwire rotation from 0° to 45°. RESULTS: All brackets ligated with stainless steel ties exhibited greater torque expression and less deformation than brackets without stainless steel ties. As well, Damon Q brackets exhibit less bracket deformation than Orthos Twin brackets. CONCLUSIONS: Stainless steel ties can reduce the amount of plastic deformation for both types of brackets used in this study.


Assuntos
Ligas Dentárias/química , Desenho de Aparelho Ortodôntico , Braquetes Ortodônticos , Fios Ortodônticos , Aço Inoxidável/química , Análise do Estresse Dentário/instrumentação , Elasticidade , Humanos , Teste de Materiais , Rotação , Estresse Mecânico , Propriedades de Superfície , Técnicas de Movimentação Dentária/instrumentação , Torque
14.
J Orthod ; 41(4): 285-91, 2014 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-24852959

RESUMO

AIMS: To better understand the effects of copper nickel titanium (CuNiTi) archwire size on bracket-archwire mechanics through the analysis of force/couple distributions along the maxillary arch. The hypothesis is that wire size is linearly related to the forces and moments produced along the arch. MATERIALS AND METHODS: An Orthodontic Simulator was utilized to study a simplified high canine malocclusion. Force/couple distributions produced by passive and elastic ligation using two wire sizes (Damon 0.014 and 0.018 inch) measured with a sample size of 144. RESULTS: The distribution and variation in force/couple loading around the arch is a complicated function of wire size. The use of a thicker wire increases the force/couple magnitudes regardless of ligation method. Owing to the non-linear material behaviour of CuNiTi, this increase is less than would occur based on linear theory as would apply for stainless steel wires. CONCLUSIONS: The results demonstrate that an increase in wire size does not result in a proportional increase of applied force/moment. This discrepancy is explained in terms of the non-linear properties of CuNiTi wires. This non-proportional force response in relation to increased wire size warrants careful consideration when selecting wires in a clinical setting.


Assuntos
Dente Canino/patologia , Arco Dental/patologia , Má Oclusão/terapia , Maxila/patologia , Desenho de Aparelho Ortodôntico , Fios Ortodônticos , Técnicas de Movimentação Dentária/instrumentação , Fenômenos Biomecânicos , Cobre/química , Ligas Dentárias/química , Elasticidade , Humanos , Níquel/química , Dinâmica não Linear , Estresse Mecânico , Titânio/química
15.
J Biomech Eng ; 135(9): 91007, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23722595

RESUMO

The periodontal ligament is the tissue that provides early tooth motion as a result of applied forces during orthodontic treatment: a force-displacement behavior characterized by an instantaneous displacement followed by a creep phase and a stress relaxation phase. Stress relaxation behavior is that which provides the long-term loading to and causes remodelling of the alveolar bone, which is responsible for the long-term permanent displacement of the tooth. In this study, the objective was to assess six viscoelastic models to predict stress relaxation behavior of rabbit periodontal ligament (PDL). Using rabbit stress relaxation data found in the literature, it was found that the modified superposition theory (MST) model best predicts the rabbit PDL behavior as compared to nonstrain-dependent and strain-dependent versions of the Burgers four-parameter and the five-parameter viscoelastic models, as well as predictions by Schapery's viscoelastic model. Furthermore, it is established that using a quadratic form for MST strain dependency provides more stable solutions than the cubic form seen in previous studies.


Assuntos
Modelos Biológicos , Ortodontia , Ligamento Periodontal , Estresse Mecânico , Animais , Dinâmica não Linear , Coelhos
16.
J Shoulder Elbow Surg ; 22(11): 1552-7, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-23639833

RESUMO

BACKGROUND: Despite the advent of locking plate techniques, proximal humeral fracture fixation can fail due to varus collapse, especially in osteoporotic bone with medial cortex comminution. This study investigated the effect of restoring the integrity of the medial column by fracture impaction and shaft medialization with locking plate fixation. This construct was compared with a traditional locking plate construct under conditions of varus cyclical loading. MATERIALS AND METHODS: Proximal humeral fractures with medial comminution were simulated by performing wedge-shaped osteotomies at the surgical neck in cadaveric specimens and removing 1 cm of medial cortex. For each cadaver (n = 6), 1 humeral fracture was fixed with a traditional locking plate construct. The other was fixed with the locking plate construct plus fracture impaction and shaft medialization, resulting in medial column restoration. The humeral head was immobilized, and a repetitive, varus force was applied to the humeral shaft until construct collapse or until 25,000 cycles were completed. RESULTS: None of the constructs with fracture impaction collapsed, whereas 5 of 6 of the nonaugmented constructs collapsed before reaching 25,000 cycles (P = .008). Collapse of the 5 nonimpacted constructs that failed occurred after an average of 11,470 ± 3589 cycles. CONCLUSION: Fracture impaction increased the ability of the locking plate to withstand repetitive varus loading. This technique provides a construct biomechanically superior to locking plate fixation alone.


Assuntos
Fixação Interna de Fraturas/instrumentação , Fixação Interna de Fraturas/métodos , Fraturas Cominutivas/cirurgia , Fraturas do Ombro/cirurgia , Idoso , Idoso de 80 Anos ou mais , Fenômenos Biomecânicos , Placas Ósseas , Cadáver , Feminino , Humanos , Masculino , Pessoa de Meia-Idade
17.
J Strength Cond Res ; 27(12): 3225-32, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-23442272

RESUMO

Jumping and weightlifting tasks involve impact phases, where work is performed by the lower extremity to absorb energies present at contact. This study compared the lower extremity kinematic and kinetic strategies to absorb energy during the impact phase of jumping and weightlifting activities. Ten women experienced in jumping and weightlifting performed 4 tasks (landing from a jump, drop landing, clean, and power clean) in a motion analysis laboratory. Work performed at the hip, knee, and ankle were calculated during the landing and receiving phases of jumping and weightlifting tasks, respectively. Additionally, segment and joint kinematics and net joint moments were determined. The most lower extremity work was performed in the clean and drop landing, followed by landing from a jump, and the least work was performed in the power clean (p < 0.05). For all tasks, work performed by the knee extensors was the greatest contributor to lower extremity work. Knee extensor net joint moment was greater in the power clean than jump and drop landings, and greater in the clean than all other tasks (p < 0.05). Knee flexion angle was not different between the power clean and jump landing (p > 0.05) but greater in the drop landing and clean (p < 0.05). A common characteristic of the impact phase of jumping and weightlifting tasks is a large contribution of knee extensor work. Further, the correspondence in kinematics between impact phases of jumping and weightlifting tasks suggests that similar muscular strategies are used to perform both types of activities. Weightlifting tasks, particularly the clean, may be important exercises to develop the muscular strength required for impact actions due to their large knee extensor net joint moments.


Assuntos
Articulação do Tornozelo/fisiologia , Exercício Físico/fisiologia , Articulação do Quadril/fisiologia , Articulação do Joelho/fisiologia , Extremidade Inferior/fisiologia , Força Muscular , Levantamento de Peso/fisiologia , Adolescente , Adulto , Fenômenos Biomecânicos , Estudos Transversais , Feminino , Humanos , Análise Multivariada , Análise e Desempenho de Tarefas , Adulto Jovem
18.
Am J Orthod Dentofacial Orthop ; 143(5): 645-57, 2013 May.
Artigo em Inglês | MEDLINE | ID: mdl-23631966

RESUMO

INTRODUCTION: Archwire rotation is used in orthodontic treatment to alter the labiolingual orientation of a tooth. Measurement of the 3-dimensional (3D) motion of the orthodontic brackets requires a new configuration of the orthodontic torque simulator. METHODS: The orthodontic torque simulator was coupled with a stereo microscope and 2 cameras to allow for the 3D bracket motion to be determined during wire twisting. The stereo camera images were processed with a 3D digital image correlation technique to determine the 3D deformation of the orthodontic brackets. Three self-ligating brackets (Damon Q, Ormco, Orange, Calif; In-Ovation R, GAC, Bohemia, NY; and Speed, Strite Industries, Cambridge, Ontario, Canada) were compared by using the 3D digital image correlation method to demonstrate the difference in 3D motion of self-ligating brackets components. RESULTS: Contour plots of the 3 brackets demonstrate the 3D motion of the bracket tie-wings and the archwire retentive component. The 3D motion of the bracket tie-wings and archwire retentive component were quantified. The displacement values of the archwire retentive component measured with the 3D orthodontic torque simulator were found to be 2.0 and 3.5 times less for the In-Ovation and Damon Q brackets than the values in previous studies that examined the compliance of the archwire retentive component. CONCLUSIONS: The 3D digital image correlation method used to quantify bracket deformation showed the 3D motion of the bracket tie-wings and the motion of the archwire retentive component. The use of a 3D optical measurement system is useful to understand the motion of the archwire retentive component but is not necessary to quantify bracket tie-wing motion. This measurement technique can be used to evaluate brackets of varying designs.


Assuntos
Análise do Estresse Dentário/instrumentação , Braquetes Ortodônticos/estatística & dados numéricos , Fios Ortodônticos/estatística & dados numéricos , Torque , Humanos , Imageamento Tridimensional , Ortodontia Corretiva/instrumentação
19.
Eur J Orthod ; 35(6): 719-29, 2013 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-21750240

RESUMO

Edgewise orthodontic treatment utilizes a force couple in order to achieve labial-lingual tooth angulation. Two self-ligating brackets (Damon Q and Speed) were examined across a range of clinically relevant torques in order to assess the loading and unloading curves and bracket deformation. A previously developed torquing and load measurement system was utilized to rotate a 0.199 × 0.25 in stainless steel wire in a fixed bracket slot to the following angles: 16, 20, 24, 28, 32, and 40 degrees. The torque on the bracket was measured during both wire loading and unloading cycles. The torque play for the Damon brackets was determined to increase by less than 0.4 degrees when torqued to 70 Nmm, whereas the increase for the Speed brackets was 2.1 degrees at the same torque magnitude. The deformation curves for the Damon and Speed brackets were found to be different for loading and unloading. Speed brackets were found to start to plastically deform when torqued to 24 degrees (26 Nmm of torque), while Damon brackets did not plastically deform until 28 degrees (38 Nmm of torque). Damon brackets were found not to plastically deform as easily and to have a smaller increase in torque play than Speed brackets. Both the Damon and the Speed brackets demonstrated minimal effect of plastic deformation and torque play at maximum angles of twist less than 20 degrees. Torque measured in the brackets was different for loading and unloading.


Assuntos
Análise do Estresse Dentário/métodos , Desenho de Aparelho Ortodôntico , Braquetes Ortodônticos , Humanos , Plásticos , Aço Inoxidável , Torque
20.
Expert Rev Med Devices ; 20(9): 729-739, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37537898

RESUMO

INTRODUCTION: A key determinant of prosthesis use is the quality of fit of the prosthetic socket. The socket surrounds the residual limb and applies the appropriate force distribution to the soft tissues to maintain suspension, support, and stabilization as well as translate limb movement to prosthesis movement. The challenge in socket fabrication lays in achieving geometry that provides the appropriate force distribution at physiologically appropriate locations; a task dependent on the understanding of interface tissue-mechanics. AREAS COVERED: In the last 20 years substantial advancements in sensor innovation and computational power have allowed researchers to quantify the socket-residual limb interface; this paper reviews prominent measurement and sensing techniques described in literature over this time frame. Advantages and short comings of each technique are discussed with a focus on translation to clinical environments. EXPERT OPINION: Prosthetic sockets directly influence comfort, device use, user satisfaction, and tissue health. Advancements in instrumentation technology have unlocked the possibility of sophisticated measurement systems providing quantitative data that may work in tandem with a clinician's heuristic expertise during socket fabrication. If validated, many of the emerging sensing technologies could be implemented into a clinical setting to better characterize how patients interact with their device and help inform prosthesis fabrication and assessment techniques.


Assuntos
Membros Artificiais , Implantação de Prótese , Humanos , Desenho de Prótese , Fenômenos Mecânicos , Extremidades , Cotos de Amputação
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