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Martins P.,University of Porto | Pena E.,Aragon Institute of Engineering Research | Pena E.,CIBER ISCIII | Jorge R.M.N.,University of Porto | And 7 more authors.
Journal of the Mechanical Behavior of Biomedical Materials | Year: 2012

The aim of this study is to characterize and model the damage process in the anterior rectus abdominal aponeurosis (anterior rectus sheath) undergoing finite deformations. The resistance of the anterolateral abdominal aponeuroses is important when planning the surgical repair of incisional hernias, among other medical procedures. Previous experiments in prolapsed vaginal tissue revealed that a softening process occurs before tissue rupture. This nonlinear damage behaviour requires a continuum damage theory commonly used to describe the softening behaviour of soft tissues under large deformations. The structural model presented here was built within the framework of non-linear continuum mechanics. Tissue damage was simulated considering different damage behaviours for the matrix and the collagen fibres. The model parameters were fit to the experimental data obtained from anterior rectus sheath samples undergoing finite deformations in uniaxial tension tests. The tests were carried out with samples cut along the direction of the collagen fibres, and transversal to the fibres. Longitudinal and transverse mechanical properties of human anterior rectus sheath are significantly different.The damage model was able to predict the stress-strain behaviour and the damage process accurately. The error estimations pointed to an excellent agreement between experimental results and model fittings. For all the fitted data, the normalized RMS error ε presented very low values and the coefficient of determination R2 was close to 1. The present work constitutes the first attempt (as far as the authors know) to present a damage model for the human rectus sheath. © 2011 Elsevier Ltd. Source


Trindade V.L.A.,University of Porto | Martins P.A.L.S.,University of Porto | Parente M.P.L.,University of Porto | Natal Jorge R.M.,University of Porto | And 3 more authors.
Journal of Biomechanics | Year: 2013

The present study focuses on the determination of the biomechanical properties for the human temporalis muscle. Eight pairs of temporalis muscles were collected from fresh cadavers and uniaxial traction tests were performed. Three specific regions were considered within the muscle: anterior, central and posterior. The results show that the central and posterior muscle regions are stiffer than the anterior ones. In order to interpret the different regional mechanical profiles observed in the temporalis muscle, a kinematic structural model for the muscle/joint system is proposed. Age influences the mechanical properties of the muscle, as older samples are apparently stiffer than younger ones. © 2013 Elsevier Ltd. Source


Trindade V.L.A.,University of Porto | Santos S.,University of Porto | Parente M.P.L.,University of Porto | Martins P.,University of Porto | And 4 more authors.
Technology and Medical Sciences, TMSi 2010 - Proceedings of the 6th International Conference on Technology and Medical Sciences | Year: 2011

The act of chewing involves the use of the four pairs of mastication muscles, the temporalis, masseter and the external and of the pterigoideus. The temporalis integration occurs in the temporal fossa and ends on the anterior mandibular ramus and coronoid apophysis, thus is main function to elevate and retract the mandible [Gray, et al. 1995], Studying the mastication muscles such as the temporal, it is an important step on understanding the bruxism pathology, which is responsible for many symptoms such as chronic headache, insomnia and sore or painful jaw that affect the patient's life quality. It is an oral parafunctional activity, characterized by the grinding of the teeth and is typically accompanied by the clenching of the jaw occurring mostly during sleep ultimately leading to temporomandibular joint dysfunction [Jadidi, et al. 2007], This biomechanical study of the temporalis aims to characterize the chosen muscle's behavior by means of the Neo-Hookean constitutive equation and it constant. The method we used was uniaxial tension testes performed on samples collected from a cadaver donor at the National Institute of Legal Medicine (INML). The Marquart-Leven's algorithm, presented at [Martins, 2009], was employed to compute the constants associated with each stress-strain graphic to the chosen constitutive model. Afterwards we compared constants by some plotting work in order to determine what would the differences be, between the three samples taken from different areas of the muscle. The conclusions will eventually lead to the recognition of the temporalis importance on the mastication muscles' group and on oral health disorders such as bruxism and temporomandibular joint pathologies. © 2011 Taylor & Francis Group. Source


Trindade V.L.A.,University of Porto | Martins P.A.L.S.,University of Porto | Santos S.,University of Porto | Parente M.P.L.,University of Porto | And 4 more authors.
Journal of Biomechanics | Year: 2012

The present study focuses on the determination of human temporal tendons and deep temporal fascia biomechanical behavior. The tensile and shear loads generated by the temporal muscle are transmitted to the masticatory system by the temporal tendons and muscle fascia. Establishing these connective tissues' biomechanical properties will help to develop proper finite element-based simulations of the human masticatory system, which will allow better understanding of diseases affecting the temporomandibular joint.The tissues were harvested from 8 male fresh cadavers, who were subjected to uniaxial tension tests. Available literature states that different connective tissues undergo identical biochemical, cellular and mechanical changes during senescence. Several mechanical phenomena occur during maturation, resulting in stiffer, stronger and more stable connective tissues, although less flexible. Based on this evidence, the present study suggests that older temporal tendon and fascia samples are stiffer than younger ones. We also found significant higher secant moduli with increasing age. © 2011 Elsevier Ltd. Source

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