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Human bite force

Bushra Malik, Terry Whittle, Toru Ogawa, Greg M Murray
The aims were to test the hypotheses that experimental masseter muscle pain leads to recruitment and/or derecruitment of motor units at different sites within the masseter and that the patterns of change in motor unit activity differ between sites. Single motor unit (SMU) activity was recorded at two sites within the right masseter [superior/anterior, inferior/posterior (IP)] during isometric biting tasks (ramp, step level) on an intraoral force transducer in 17 participants during three experimental blocks comprising no infusion (baseline), 5% hypertonic saline infusion (pain), or isotonic saline infusion (control)...
July 30, 2018: European Journal of Oral Sciences
Isbel Sandoval, Polyana Moura Ferreira, Fabian Obregon, Terry Whittle, Greg M Murray
AIM: To determine if the electromyographic (EMG) activity of the left and right masseter and anterior temporalis muscles is altered by experimental right masseter muscle noxious stimulation during goal-directed isometric biting tasks in asymptomatic humans. METHODS: Isometric biting tasks (slow and fast ramp biting tasks, 2-step biting task) were performed on an intraoral force transducer in 18 participants during the following blocks: baseline block, hypertonic saline infusion into the right masseter muscle (painful block), and isotonic saline infusion into the right masseter (control block)...
July 19, 2018: Journal of Oral Rehabilitation
Sudhir Ramlal Pawar, Rajesh Ashok Kshirsagar, Pratik Hemantkumar Raut, Amod Pramod Patankar
Although leopards are found worldwide, the incidence of leopard attack on humans is reported most often from India and Nepal. Usually, leopards avoid contact with people, but humans may occasionally be targeted as prey. Animal bite wounds may express as punctures, abrasions, tears, or avulsions. The force and bluntness of the teeth increase the probability of a crush injury with devitalized tissue. The clinical presentation and appropriate treatment of infected bite wounds vary according to extent of the wound...
January 2018: National Journal of Maxillofacial Surgery
Eduardo I Faúndez
Bagrada hilaris is an invasive stink bug present in Asia, Africa, Europe, North America, and recently found in Chile, South America. Painted bug is well known as an agricultural pest, attacking mostly Brassicaceae. First records of the painted bug B. hilaris invading homes are given from Chile, from the Metropolitan, and Valparaiso Regions, including mild and heavily infested homes. In addition, the first case ever of an adventitious bite in a human being by this species is provided and described. Additionally, first alleged cases of occupational allergy are also mentioned...
June 20, 2018: Journal of Medical Entomology
Herzl Chai
Fossil teeth are a primary source for inferring species development via evolutionary adaptation due to their linkage to feeding ecology and well perseverance. The main working tools in such studies are bite force analysis derived from jaw musculature and lever arms and morphogenetic based on enamel thickness and occlusal surface area. Despite progress made, quantitative correlation between predictions and behavior is still lacking. We studied histological sections in varieties of extracted premolar and molar human teeth...
June 3, 2018: Acta Biomaterialia
David Ackland, Dale Robinson, Peter Vee Sin Lee, George Dimitroulis
BACKGROUND: Stock prosthetic temporomandibular joint replacements come in limited sizes, and do not always encompass the joint anatomy that presents clinically. The aims of this study were twofold. Firstly, to design a personalized prosthetic total joint replacement for the treatment of a patient's end-stage temporomandibular joint osteoarthritis, to implant the prosthesis into the patient, and assess clinical outcome 12-months post-operatively; and secondly, to evaluate the influence of changes in prosthetic condyle geometry on implant load response during mastication...
July 2018: Clinical Biomechanics
Robert Prose, Nicole E Breuner, Tammi L Johnson, Rebecca J Eisen, Lars Eisen
Clothing treated with the pyrethroid permethrin is available in the United States as consumer products to prevent tick bites. We used tick bioassays to quantify contact irritancy and toxicity of permethrin-treated clothing for three important tick vectors of human pathogens: the blacklegged tick, Ixodes scapularis Say (Acari: Ixodidae); the lone star tick, Amblyomma americanum (L.) (Acari: Ixodidae); and the American dog tick, Dermacentor variabilis (Say) (Acari: Ixodidae). We first demonstrated that field-collected I...
May 24, 2018: Journal of Medical Entomology
Heidi Haavik, Mustafa Görkem Özyurt, Imran Khan Niazi, Kelly Holt, Rasmus Wiberg Nedergaard, Gizem Yilmaz, Kemal Sitki Türker
Recent research has shown that chiropractic spinal manipulation can alter central sensorimotor integration and motor cortical drive to human voluntary muscles of the upper and lower limb. The aim of this paper was to explore whether spinal manipulation could also influence maximal bite force. Twenty-eight people were divided into two groups of 14, one that received chiropractic care and one that received sham chiropractic care. All subjects were naive to chiropractic. Maximum bite force was assessed pre- and post-intervention and at 1-week follow up...
April 27, 2018: Brain Sciences
M Koutris, K S Türker, M K A van Selms, F Lobbezoo
The effects of masticatory muscles' overloading on jaw-motor control are not yet fully clarified. Therefore, it was tested whether eccentric and concentric exercises of the human masticatory muscles would influence inhibitory jaw reflex responses. Eleven participants (6 males, 5 females) performed 6, 5-minutes bouts of eccentric-concentric contractions. Before, immediately after, 24 hours, 48 hours and 1 week afterwards, visual analogue scale (VAS) scores for jaw muscle fatigue and pain, maximum voluntary bite force (MVBF) and inhibitory jaw reflexes were recorded...
June 2018: Journal of Oral Rehabilitation
Stephen Wroe, William C H Parr, Justin A Ledogar, Jason Bourke, Samuel P Evans, Luca Fiorenza, Stefano Benazzi, Jean-Jacques Hublin, Chris Stringer, Ottmar Kullmer, Michael Curry, Todd C Rae, Todd R Yokley
Three adaptive hypotheses have been forwarded to explain the distinctive Neanderthal face: (i) an improved ability to accommodate high anterior bite forces, (ii) more effective conditioning of cold and/or dry air and, (iii) adaptation to facilitate greater ventilatory demands. We test these hypotheses using three-dimensional models of Neanderthals, modern humans, and a close outgroup ( Homo heidelbergensis ), applying finite-element analysis (FEA) and computational fluid dynamics (CFD). This is the most comprehensive application of either approach applied to date and the first to include both...
April 11, 2018: Proceedings. Biological Sciences
Ricardo Miguel Godinho, Laura C Fitton, Viviana Toro-Ibacache, Chris B Stringer, Rodrigo S Lacruz, Timothy G Bromage, Paul O'Higgins
Modern humans have smaller faces relative to Middle and Late Pleistocene members of the genus Homo. While facial reduction and differences in shape have been shown to increase biting efficiency in Homo sapiens relative to these hominins, facial size reduction has also been said to decrease our ability to resist masticatory loads. This study compares crania of Homo heidelbergensis and H. sapiens with respect to mechanical advantages of masticatory muscles, force production efficiency, strains experienced by the cranium and modes of deformation during simulated biting...
May 2018: Journal of Human Evolution
Sandipan Roy, Mainak DAS, Pratyaya Chakraborty, Jayanta Kumar Biswas, Subhomoy Chatterjee, Niloy Khutia, Subrata Saha, Amit Roy Chowdhury
PURPOSE: Bone quality varies from one patient to another extensively. Young's modulus may deviate up to 40% of normal bone quality, which results into alteration of bone stiffness immensely. The prime goal of this study is to design the optimum dental implant considering the mechanical response at bone implant interfaces for a patient with specific bone quality. METHOD: 3D models of mandible and natural molar tooth were prepared from CT scan data, while dental implants were modelled using different diameter, length and porosity and FE analysis was carried out...
2017: Acta of Bioengineering and Biomechanics
Mônica da Consolação Canuto Salgueiro, Carolina Carvalho Bortoletto, Anna Carolina RattoTempestini Horliana, Ana Carolina Costa Mota, Lara Jansiski Motta, Pamella de Barros Motta, Raquel Agnelli MesquitaFerrari, Kristianne Porta Santos Fernandes, Sandra Kalil Bussadori
BACKGROUND: Bruxism is a repetitive activity that causes tooth wear, audible sounds, and discomfort. Preventive measures have been studied for conditions that can exert a negative influence on physiological development in children. Low-level laser therapy administered over acupoints is an effective, painless, low-cost treatment option that has achieved good results. Thus, the aim of the proposed study is to evaluate changes in muscle activity, bite force and salivary cortisol in children with bruxism after the application of low-level laser to accupoints...
August 8, 2017: BMC Complementary and Alternative Medicine
Lixian Zhang, Yaqi Zheng, Qiong Rong, Guofeng Wu
BACKGROUND: Muscles converge or intertweave around the perioral area, and this can be treated with sequential therapy in infants with cleft lip and palate (CLP). The force of perioral muscles has a great influence on maxillary development and morphology. Perioral force in infants with CLP has not been well studied, and accurate and reliable measurement of perioral force in infants remains a challenge. This study aimed to investigate a new way to accurately and reliably measure perioral force in infants with unilateral CLP (UCLP) and explore the change before and after cheiloplasty...
November 2017: Journal of Plastic, Reconstructive & Aesthetic Surgery: JPRAS
James Ij Green
a mouthguard, also known as a gumshield, mouth protector or sports guard is an appliance that covers the teeth and surrounding mucosa with the aim of preventing or reducing trauma to the teeth, gingival tissue, lips and jaws. The device is usually worn on the maxillary arch and works by separating the maxillary and mandibular dentition, protecting the teeth from the surrounding soft tissue, absorbing or redistributing shock and/or stabilising the mandible during traumatic jaw closure. They may also play a role in preventing and reducing concussion by absorbing impact forces that would otherwise be transmitted through the base of the skull to the brain, although the evidence for this is less conclusive...
May 1, 2017: Primary Dental Journal
Hsin-Chung Cheng, Boe-Yu Peng, May-Show Chen, Chiung-Fang Huang, Yi Lin, Yung-Kang Shen
Endosseous oral implant is applied for orthodontic anchorage in subjects with multiple tooth agenesis. Its effectiveness under orthodontic loading has been demonstrated clinically and experimentally. This study investigates the deformation and stress on the bone and implant for different bite forces by three-dimensional (3D) finite element (FE) methods. A numerical simulation of deformation and stress distributions around implants was used to estimate the survival life for implants. The model was applied to determine the pattern and distribution of deformations and stresses within the endosseous implant and on supporting tissues when the endosseous implant is used for orthodontic anchorage...
2017: BioMed Research International
L R Iwasaki, Y M Gonzalez, Y Liu, H Liu, M Markova, L M Gallo, J C Nickel
Cartilage fatigue may be a factor in the precocious development of degenerative changes in the temporomandibular joint (TMJ). This cross-sectional study estimated potential for cartilage fatigue via TMJ energy densities (ED) and jaw muscle duty factors (DF), which were combined to calculate mechanobehavioral scores (MBS) in women with (+) and without (-) bilateral TMJ disc displacement (DD). All subjects gave informed consent to participate and were examined using Diagnostic Criteria (DC) for Temporomandibular Disorders (TMD) and magnetic resonance (MR) and computed tomography (CT) images...
July 2017: Journal of Dental Research
V Pommier de Santi, I Dusfour, E de Parseval, B Lespinet, C Nguyen, P Gaborit, R Carinci, G Hyvert, R Girod, S Briolant
Between 2008 and 2014, there were 1070 malaria cases reported in French Guiana among members of the armed forces. Most of the malaria outbreaks investigated were multifactorial and followed missions conducted at illegal gold mining sites. For example, a malaria outbreak occurred in September 2013, three weeks after the deployment of 15 soldiers at Dagobert, which is such a site. The attack rate was 53%, with seven Plasmodium vivax infections and one coinfection with both Plasmodium vivax and Plasmodium falciparum...
February 1, 2017: Médecine et Santé Tropicales
M A Masud, Byul Nim Kim, Yongkuk Kim
Dengue viruses (DENV) are transmitted to humans by the bite of Aedes mosquitoes. It is known that dengue virus infection in Aedes aegypti female mosquitoes makes a change in the feeding behavior of the infected mosquitoes. In this study, using the forces of infection, we incorporated the effect of changes in the feeding behavior of mosquitoes into the standard vector-borne SIR-SI model. It has been proved that both a single-strain model and a two-strain model exhibit forward bifurcations. Moreover, optimal implementations of control with specific prevention measures for dengue transmission are analyzed...
June 2017: Bio Systems
Xing Weibin, Zheng Shuxian, Yang Shiyi
OBJECTIVE: Finite elemental analysis of the mechanical characteristics of a first mandibular implant molar under different mandibular plane angles determines the load conditions on the implant, thereby providing guidance for clinical application. METHODS: CT data of three mandibular plane angles (low, average, high) were collected. A finite elemental combination model of a dental implant was constructed. The orthogonal experimental research was designed. Results followed data collection and analysis...
October 1, 2016: Hua Xi Kou Qiang Yi Xue za Zhi, Huaxi Kouqiang Yixue Zazhi, West China Journal of Stomatology
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