Academic literature on the topic 'Mechanical mastication'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Mechanical mastication.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Mechanical mastication"
1
Rolere, Sébastien, Florian Deme, Jérôme Sainte-Beuve, and Frédéric Bonfils. "EFFECT OF MASTICATION ON THE STRUCTURE OF MICROGEL PRESENT IN NATURAL RUBBER." Rubber Chemistry and Technology 90, no. 3 (July 1, 2017): 445–54. http://dx.doi.org/10.5254/rct.16.83766.
Full textAbstract:
ABSTRACT Mechanical or thermal mastication experiments were performed on three commercial natural rubber (NR) samples of TSR10 grade made from latex of three different clones (GT1, PB235, and RRIM600). The mesostructure (different gel or aggregate fractions, structure of random coils of cis-1,4-polyisoprene) of all the NR samples was fully characterized by size exclusion chromatography coupled with multiangle light scattering (SEC-MALS), using pretreated SEC columns. This method was used to quantify and investigate the structure of the little-studied smaller microaggregates, constituting the microgel fraction smaller than 1 μm (Microgel<1μ) of NR. The three unmasticated NR samples showed no difference in terms of microaggregate structure. Conversely, microaggregates appeared denser after mastication. This phenomenon was found to depend on the mastication conditions, as mechanically masticated NR samples had smaller (lower radius of gyration) and more compact microaggregates than thermally masticated samples. Macrogel also behaved differently depending on the mastication conditions. Mechanical mastication conditions allowed a higher degradation of the macrogel compared with thermal mastication conditions.
2
Southworth, Darlene, Jessica Donohue, Jonathan L. Frank, and Jennifer Gibson. "Mechanical mastication and prescribed fire in conifer - hardwood chaparral: differing responses of ectomycorrhizae and truffles." International Journal of Wildland Fire 20, no. 7 (2011): 888. http://dx.doi.org/10.1071/wf10033.
Full textAbstract:
Fire-prone hardwood–conifer chaparral comprises a significant component of vegetation in seasonally dry areas where prescribed burns of standing vegetation are limited by air-quality restrictions and narrow climatic opportunities for burning. Mechanical mastication is used by land managers to reduce aerial fuels. When burned, the dry masticated slash layer may result in prolonged soil heating, particularly of the upper soil layers, which contain ectomycorrhizal roots and seasonal truffles (hypogeous fungal sporocarps). The purpose of this study was to examine the effects of mechanical mastication followed by prescribed fire on ectomycorrhizae and truffles. We treated blocks with mechanical mastication only, mechanical mastication followed by prescribed fire, prescribed fire only, and no treatment. Five years after the prescribed burn, soils with ectomycorrhizal roots were sampled at the canopy dripline of Pinus attenuata and Quercus kelloggii and surveyed for truffles. Ectomycorrhizae and truffles were described by morphology and by DNA sequences of the internal transcribed spacer region. Ectomycorrhizal communities did not differ among treatments. However, burning reduced the abundance and species richness of truffles in both controls and masticated vegetation. We conclude that prescribed burning of mechanically masticated slash does not harm ectomycorrhizal communities, but does inhibit fruiting of truffles.
3
Grant, Madeleine A., Thomas J. Duff, Trent D. Penman, Bianca J. Pickering, and Jane G. Cawson. "Mechanical Mastication Reduces Fuel Structure and Modelled Fire Behaviour in Australian Shrub Encroached Ecosystems." Forests 12, no. 6 (June 20, 2021): 812. http://dx.doi.org/10.3390/f12060812.
Full textAbstract:
Shrub encroachment of grassland and woodland ecosystems can alter wildfire behaviour and threaten ecological values. Australian fire managers are using mechanical mastication to reduce the fire risk in encroached ecosystems but are yet to evaluate its effectiveness or ecological impact. We asked: (1) How does fuel load and structure change following mastication?; (2) Is mastication likely to affect wildfire rates of spread and flame heights?; and (3) What is the impact of mastication on flora species richness and diversity? At thirteen paired sites (masticated versus control; n = 26), located in Victoria, Australia, we measured fuel properties (structure, load and hazard) and floristic diversity (richness and Shannon’s H) in 400 mP2 plots. To quantify the effects of mastication, data were analysed using parametric and non-parametric paired sample techniques. Masticated sites were grouped into two categories, 0–2 and 3–4 years post treatment. Fire behaviour was predicted using the Dry Eucalypt Forest Fire Model. Mastication with follow-up herbicide reduced the density of taller shrubs, greater than 50 cm in height, for at least 4 years. The most recently masticated sites (0–2 years) had an almost 3-fold increase in dead fine fuel loads and an 11-fold increase in dead coarse fuel loads on the forest floor compared with the controls. Higher dead coarse fuel loads were still evident after 3–4 years. Changes to fuel properties produced a reduction in predicted flame heights from 22 m to 5–6 m under severe fire weather conditions, but no change in the predicted fire rate of spread. Reductions in flame height would be beneficial for wildfire suppression and could reduce the damage to property from wildfires. Mastication did not have a meaningful effect on native species diversity, but promoted the abundance of some exotic species.
4
Young, Kert R., Bruce A. Roundy, and Dennis L. Eggett. "Mechanical Mastication of Utah Juniper Encroaching Sagebrush Steppe Increases Inorganic Soil N." Applied and Environmental Soil Science 2014 (2014): 1–10. http://dx.doi.org/10.1155/2014/632757.
Full textAbstract:
Juniper (Juniperusspp.) has encroached on millions of hectares of sagebrush (Artemisiaspp.) steppe. Juniper mechanical mastication increases cover of understory species but could increase resource availability and subsequently invasive plant species. We quantified the effects of juniper mastication on soil resource availability by comparing total C, total N, C : N ratio, Olsen extractable P, sulfate S, and pH using soil samples and inorganic N (NO3-+NH4+) using ion exchange membranes. We compared resource availability in paired masticated and untreated areas in three juniper-dominated sagebrush and bunchgrass ecosystems in the Utah portion of the Great Basin. Inorganic N was 4.7 times higher in masticated than in untreated areas across seasons (P<0.001). Within masticated areas, tree mounds of juniper leaf scales and twigs served as resource islands with 1.9 times higher inorganic N and total C, and 2.8 times higher total N than bare interspaces across seasons (P<0.01). Bare interspaces had 3.0–3.4 times higher inorganic N than interspaces covered with masticated trees during late-summer through winter (P<0.01). Soil fertility changes associated with mastication were not considered sufficient to favor establishment of annual over perennial grasses, and we expect both to increase in cover following juniper mastication.
5
Takanishi, Atsuo. "Development of Mastication Robot WJ-1." Journal of Robotics and Mechatronics 1, no. 3 (October 20, 1989): 185–91. http://dx.doi.org/10.20965/jrm.1989.p0185.
Full textAbstract:
The purpose of this study was to establish a dynamic, quantitative engineering model for the mandible movement in man's mastication by reproducing this movement by using a mechanical model and to define the mandible movement controlling mechanism from the viewpoint of engineering. To realize this purpose, WJ (Waseda Jaw)1, a 1 degree of freedom mastication robot, was developed. The following is a description of the mastication robot WJ-1 with reference to man's actual mandible movement.
6
EARAR, Kamel, and Dragos Nicola FRATILA. "DIGESTIVE DISORDERS IN THE ORAL CAVITY." Medicine and Materials 1, no. 1 (June 15, 2021): 23–30. http://dx.doi.org/10.36868/medmater.2021.01.01.023.
Full textAbstract:
The progress made in fundamental medical research over the past decades, the scientific acquisitions in the field of genetics, molecular biology and biochemistry in relation to the explosive development of investigative technologies have revolutionized the clinical approach to many pathological entities, practically opening a new era in the evolution of clinical medicine. Dental medicine, as a science, feels the massive impact of the needs for knowledge and relaunches the interest of research in all its subspecialties. From this perspective, these are legitimized not only through the crisis in managing the immense volume of information, but also through the openings offered to the framework of conceptualizing and defining the identity of this branch of medicine, related to the need to particularize the specific problems in this discipline. Digestion is a fundamental process in the survival of an organism. It begins in the oral cavity, where the bolus is formed, and continues in the stomach, forming the chyme, which then reaches the small intestine and transforms into the chyle. Through mastication, the surface of food increases, thus the enzymes are able to act more easily on the substrate. The first enzymes to act on food are the salivary ones - salivary amylase, lingual lipase. Mastication is regulated through the contact of food with receptors in the oral cavity. These will send impulses by way of the trigeminal nerve towards the centre of mastication - located in the bolus. From the bolus, they will start the signals on the efferent pathway (trigeminal, hypoglossal and facial nerves) that will reach the masticatory muscles. Mechanical digestion (mastication) can thus begin. Mechanical digestion in the oral cavity results from mastication. During mastication, the food is manipulated by the tongue, crushed by the teeth and mixed with saliva. Concomitant with mechanical digestion, the chemical digestion takes place through the action of saliva. There are two types of salivary glands in the oral cavity: large glands - parotid, sublingual, submandibular and small glands - disseminated throughout the oral cavity. Within 24 hours, up to 1.5 liters of saliva are secreted, 99% of which is represented by water. The remaining 1% consists of enzymes, mucus, nitrogen content. After finalizing mastication, deglutition begins. This mechanical process consists of thrusting the bolus from the mouth towards the stomach, using the esophagus.
7
Nasruddin, Nasruddin, and Tri Susanto. "Study of the Mechanical Properties of Natural Rubber Composites with Synthetic Rubber Using Used Cooking Oil as a Softener." Indonesian Journal of Chemistry 20, no. 5 (July 18, 2020): 967. http://dx.doi.org/10.22146/ijc.42343.
Full textAbstract:
This research aims to study the mechanical properties of natural rubber composites with nitrile butadiene rubber and ethylene propylene diene monomer rubber. Composite fillers consisted of kaolin, and softener using used cooking oil. The study was carried out by the method of mastication, vulcanization, and maturation of the compound into rubber vulcanizates. The vulcanization and mastication process is carried out in the open mill. The maturation of the compound into rubber vulcanizates from the results of mastication and vulcanization was carried out using semi-automatic heat press and press at a temperature of 130 °C ± 2 °C for 17 min. Based on data from testing the mechanical properties of five samples from five formulas, the mechanical properties of composite rubber are affected by the ratio of natural rubber, synthetic rubber, kaolin, and used cooking oil as a softener. The difference in the results of vulcanizates rubber testing of natural rubber composites with synthetic rubber is not only influenced by the ratio of the composite, but also by the degree of cross-linking between the material molecules.
8
Rusu, Lucian, Cosmina Vigaru, and Dan Ioan Stoia. "Determination of Mastication Forces in Case of Total Dental Prosthesis." Key Engineering Materials 638 (March 2015): 145–50. http://dx.doi.org/10.4028/www.scientific.net/kem.638.145.
Full textAbstract:
In whole wide world, lots of individuals lose teeth from different causes. In these cases, in first phase, a dental implant is the best solution. In some cases, as the last solution, a dental prosthesis is needed. To correct these disorders, rehabilitation treatments with adequate dentures, either fixed or removable, are indicated. [6] The forces that appear during mastication are influenced by occlusion type and space distribution of teeth. In case of persons that have a dental prosthesis the forces that occurred during mastication can be reduced if the dental prosthesis is correctly generated. A mastication simulator is any device that reproduces the conditions present during the process of chewing in order to reconstruct the complicated process of mastication outside the body. [5] The aim of this paper is to produce a device that can simulate the mastication and use it to determinate the mastication forces that appears during the mastication of different foods types. On the device that was build can be placed different dental prosthesis. [2] Using the device adjustment facilities we are able to simulate any type of occlusion. Using this device, a mechanical testing equipment and different types of food we are able to determinate the vertical force that occur. Base on these results we will be able to determinate if the dental prosthesis was correctly produced.
9
Brennan, Teresa J., and Jon E. Keeley. "Effect of mastication and other mechanical treatments on fuel structure in chaparral." International Journal of Wildland Fire 24, no. 7 (2015): 949. http://dx.doi.org/10.1071/wf14140.
Full textAbstract:
Mechanical fuel treatments are a common pre-fire strategy for reducing wildfire hazard that alters fuel structure by converting live canopy fuels to a compacted layer of dead surface fuels. Current knowledge concerning their effectiveness, however, comes primarily from forest-dominated ecosystems. Our objectives were to quantify and compare changes in shrub-dominated chaparral following crushing, mastication, re-mastication and mastication-plus-burning treatments, and to assess treatment longevity. Results from analysis of variance (ANOVA) identified significant differences in all fuel components by treatment type, vegetation type and time since treatment. Live woody fuel components of height, cover and mass were positively correlated with time since treatment, whereas downed woody fuel components were negatively correlated. Herbaceous fuels, conversely, were not correlated, and exhibited a 5-fold increase in cover across treatment types in comparison to controls. Average live woody fuel recovery was 50% across all treatment and vegetation types. Differences in recovery between time-since-treatment years 1–8 ranged from 32–65% and exhibited significant positive correlations with time since treatment. These results suggest that treatment effectiveness is short term due to the rapid regrowth of shrubs in these systems and is compromised by the substantial increase in herbaceous fuels. Consequences of not having a full understanding of these treatments are serious and leave concern for their widespread use on chaparral-dominated landscapes.
10
Hatchett, B., Michael P. Hogan, and Mark E. Grismer. "Mechanical mastication thins Lake Tahoe forest with few adverse impacts." California Agriculture 60, no. 2 (April 2006): 77–82. http://dx.doi.org/10.3733/ca.v060n02p77.
Full textDissertations / Theses on the topic "Mechanical mastication"
1
Bybee, Jordan Ann. "Understory Vegetation Response to Mechanical Mastication of Piñon and Juniper Woodlands." BYU ScholarsArchive, 2013. https://scholarsarchive.byu.edu/etd/3817.
Full textAbstract:
Piñon and juniper encroachment and infilling can alter ecosystem processes and decrease resilience and resistance in sagebrush grasslands. Land managers employ a variety of techniques to eliminate these trees and mitigate their negative effects. Mechanical mastication or shredding is an increasingly popular method of removing these trees in Utah. It is a versatile treatment that can reduce canopy fuels, increase infiltration, and reduced sediment loss. We compared vegetation cover for annual and perennial vegetation functional groups on shredded and adjacent unshredded areas across a range of sites. Our approach was to categorize sites by ecological site type (encroachment or tree) and subplots by treatment (untreated, shredded, and shredded-seeded) and initial tree cover. Mixed model analysis of covariance and the Tukey-Kramer test were used to determine significant differences among ecological site type and treatment combinations for each 5% increment of untreated or initial tree cover. Shrub cover was unaffected by treatment and decreased with increasing tree cover. In general, perennial herbaceous understory cover increased after shredding to equal or exceed initial encroachment and infilling levels. This held true for both ecological site types and treatments, even at high pretreatment tree cover percentages. Cheatgrass also increased in cover after tree shredding although this trend was dampened in the seeded treatments indicating some suppression of cheatgrass by seeding. Shredding when there is high cover of perennial herbaceous plants and shrubs or seeding in conjunction with shredding where initial tree cover exceeds 35-40% will help discourage dominance by weeds.
2
Shakespear, Alan Wyatt. "Fuel Response to Mechanical Mastication of Pinyon-Juniper Woodlands in Utah." BYU ScholarsArchive, 2014. https://scholarsarchive.byu.edu/etd/4317.
Full textAbstract:
Pinyon-juniper woodland encroachment threatens ecosystem function and diversity on sagebrush steppe. Decreased fire frequency likely favors proliferation of pinyon-juniper woodlands and subsequent decline in desirable understory species. Increased tree cover produces hazardous canopy fuel loads that contribute to severe crown fires and threaten life and property at the wildland-urban-interface. Mechanical mastication converts large canopy fuels into small woody debris, altering wildfire dynamics from a potential crown fire to a more controllable surface fire. We measured fuel loading and cover on untreated, masticated, and masticated + burned treatments on 30-m transects within 30 X 33-m subplots, representing 45 different sites throughout Utah. All variables were analyzed using mixed-model analysis of covariance with untreated or pretreatment tree cover as the covariate. Shredding trees reduced large-diameter fuels to primarily 10-hour fuels (6.4-25.4 mm diameter). Reduced fuel sizes, fuel redistribution, and fuelbed compactness resulting from mastication treatments can aid wildfire suppression. Masticated + burned treatments effectively reduced woody surface fuel loading to that of pretreatment conditions. Prescribed burning could be used outside the growing season in cool-weather, high-moisture conditions to remove surface fuels, mitigating lethal soil heating and plant mortality. Shrub loading was not adversely affected by mastication treatments, but was significantly reduced with masticated + burned treatments. Masticated and masticated + burned treatments significantly increased herbaceous fuel loading. Treating at lower tree cover values reduced fuel buildup, and provided more opportunity for a positive herbaceous response. Fuel loading estimates measured in this study were provided to populate fire behavior models for mastication treatments on our study sites when such models become available.
3
Zink, Katherine Diane. "Mechanical and Thermal Food Processing Effects on Mastication and Cranio-Dental Morphology." Thesis, Harvard University, 2013. http://dissertations.umi.com/gsas.harvard:10900.
Full textAbstract:
Chimpanzees spend ~40% of their day chewing fruits, seeds, and tough leaves and pith, while in contrast modern humans spend significantly less time eating (5%), and the foods that they consume are extremely soft and processed. How have these differences, especially the advent and increasing use of foods processing techniques, influenced masticatory effort and ultimately the morphology of the jaws and teeth? This dissertation addresses this question by measuring the effects that early hominin food processing methods (slicing, pounding, and roasting) have on food material properties, masticatory performance and functional integration of the teeth and jaws. Using standard testing techniques, the material properties of plant tubers and meat were quantified. Processing had contrasting effects on the properties of these foods, and were correlated with masticatory performance changes measured in human experiments. Mechanical processing techniques decreased tuber toughness, leading to lower chew force (CF). Roasting further decreased tuber toughness and other material properties, which led to lower comminution efficiency (CE) and CF. In direct contrast to tubers, mechanical processing techniques did not alter meat toughness, yet did increase CF and CE. Roasting the meat also increased CF and CE, likely because of higher toughness and stiffness, coupled with less elastic energy loss. The generation of lower masticatory forces resulting from processing have undoubtedly affected cranio-dental morphology. In particular, it is hypothesized that forces functionally integrate the masticatory system, and reduced forces, especially in modern human populations, lead to malocclusions (dis-integration). An animal experiment was performed to test this hypothesis, and the results indicate that masticatory effort (eating hard or soft foods) coordinates jaw and dental growth. Further testing the hypothesis, the effects of morphology on masticatory function were studied by coupling subject masticatory performance with occlusal scores. Multiple regressions of occlusion and tooth size explained a high proportion of masticatory performance variance (significantly more than tooth size alone), suggesting that occlusal integration does indeed affect masticatory function. Taken together, the results of this dissertation document the significant reductions in hominin masticatory forces and changes in cranio-dental growth and integration that may have resulted from the use of food processing techniques.Human Evolutionary Biology
4
Reed, Warren Paul. "Long-term Fuel and Vegetation Responses to Mechanical Mastication in northern California and southern Oregon." Thesis, Virginia Tech, 2016. http://hdl.handle.net/10919/71295.
Full textAbstract:
Historical land use and changes in climate have altered fire behavior and severity in fire-prone ecosystems of western North America. A variety of fuels treatments are used to abate fire hazard, restore ecosystem processes, and increase forest resilience. Mechanical fuels treatments are increasingly used to alter forest structure and fuel continuity due to impediments to the use of prescribed fire. An increasingly common fuels treatment is mechanical mastication. Mastication does not remove fuels, but instead rearranges live and dead vertical woody fuels into a compacted layer on the forest floor. While mastication reduces potential fire intensity, these compacted fuels are flammable and capable of causing tree mortality and other negative ecological consequences when they burn in prescribed fires or wildfires. A current knowledge gap is quantitative information about the rate at which masticated fuels decompose and the rate at which vegetation reestablishes within sites previously masticated. Using 25 sites across northern California and southern Oregon, this thesis examines how masticated fuels change over time. Results from this study demonstrate that the majority of mass lost from masticated fuel beds occurred in the 1 and 10-hour woody fuel classes. Because surface fire behavior is driven by these fine fuels, these findings are valuable to the planning and retreatment of masticated fuels treatments and the corresponding fire suppression efforts in masticated sites. In combination with masticated wood surface fuels, shrubs and small trees play an important role in fire behavior, acting as ladder fuels that exacerbate surface fire behavior and threaten to ignite residual trees. A lack of understanding of how woody vegetation recovers following masticated fuel treatments gives rise to questions and challenges regarding treatment longevity. In this study, species with the ability to resprout tended to recover more quickly than obligate seeding species. Residual conifer saplings or trees that establish in masticated fuelbeds also recovered rapidly, reducing the efficacy of fuels treatments. Future implementation of masticated fuels treatments should consider both woody fuel decomposition and the corresponding recovery of shrubs and small trees to maximize treatment longevity.Master of Science
5
Patriquin, Michelle Lyn. "The relationship between masticatory stress and prognathism : a finite element and morphometric study." Thesis, University of Pretoria, 2013. http://hdl.handle.net/2263/36682.
Full textAbstract:
Mechanical forces, such as mastication, influence morphological characteristics of the cranium. With varying degrees of prognathism found within and between populations, the ability to accommodate masticatory stress may vary, and this will have profound effects on final craniofacial form. The purpose of this research is a two-fold examination of mid-facial prognathism in modern African males. First, an osteometric and morphological examination of specific areas of the cranium involved in the masticatory apparatus was performed, and its relationship with prognathism assessed. Second, finite element analysis (FEA) was used to interpret the distribution of stress during mastication and the contribution of prognathism to this stress distribution. Two diametrically opposed facial forms (prognathic and orthognathic) were modelled to observe variation in displacement, pressure, and Von Mises stress patterns using linear elastic homogenous isotropic material properties.
Boundary conditions simulating muscle contraction of the masseter, medial pterygoid, and temporalis were attributed to the models. A vertical compressive bite-force was applied at the left central incisor and the first molar, respectively. With the use of FEA, differences in the pattern and magnitude of Von Mises stress were noted under simulated mastication. The prognathic model consistently experienced more stress for a molar and incisal bite-force than the orthognathic model. More specifically, the prognathic model accommodated for larger areas of Von Mises stress in the regions of the zygomatic arch, nasal aperture, margins of the orbits, and in the inter-orbital area. As individual muscle forces were modeled, the temporalis and medial pterygoid caused the greatest difference in the stress at the articular eminence between the working and balancing sides. These muscles and their forces should be further investigated to understand their role in temporomandibular joint disorders.
Several cranial dimensions were shown to increase or decrease with prognathism. The relationship between the gnathic index and facial parameters were statistically significant for nine cranial and seven dental dimensions. The orthognathic group showed a larger inter-orbital dimension with a subsequent decrease in stress in that area. The upper facial index, maxillary molar crown area and the dental arcade shape demonstrated statistically significant shape changes associated with the degree of prognathism. Morphological analysis did not show a significant distribution in browridge expression and robusticity as a means to accommodate masticatory stress. Stress distribution patterns were correlated with osteometric data and showed a significant difference in inter-orbital breadth between the two groups.
Mechanical action of mastication may influence prognathic more than orthognatic facial forms. An orthognatic facial form is biomechanically more efficient under masticatory stress. Mechanical loading during mastication greatly influences the morphological patterns of the facial skeleton. Further investigation into patterns of stress is necessary when changes to the masticatory apparatus arises from clinical involvement, trauma, or as a means to avoid or predict failure in the underlying skeletal architectuThesis (PhD)--University of Pretoria, 2014.
Anatomy
unrestricted
6
Atassi, Mounir. "Mechanical monitoring of inhibitory jaw reflexes in health and simulated dysfunction." Thesis, University of Dundee, 2014. https://discovery.dundee.ac.uk/en/studentTheses/abca297e-8951-447b-8c9e-0bb529d211a9.
Full textAbstract:
Objectives: Previous studies in the Oral Neurophysiology Laboratories in Dundee have defined the electromyographic properties of the inhibitory jaw reflex that can be evoked in human subjects by electrical stimulation of the lip. This reflex, in contrast with the more widely studied biphasic inhibitory reflexes evoked by stimulation of intra-oral nerves, consists of just a single phase of inhibition and usually requires the application of stimuli which excite nociceptive nerves. The aims of the present studies were to define the mechanical manifestations of this reflex in the form of changes in biting forces, and to investigate whether the mechanical manifestation of the inhibitory jaw reflex evoked by stimulation of the human upper lip, can be modulated by experimentally-controlled conditions that mimic symptoms of a myogenous temporomandibular disorder. Methods: Three series of experiments were performed on 49 volunteer subjects in total. The experiments involved recording bite forces between the anterior teeth and electromyograms (EMGs) from the masseter muscles. Transcutaneous electrical stimuli were applied to the hairy skin of upper lip while the subjects maintained a biting force of around 50N with the aid of visual feedback. In the first series of experiments, a range of electrical stimuli below and above the nociceptive threshold was delivered. In the second set of experiments, double stimuli with a range of different inter-stimulus intervals were applied. Finally in a third series of experiments, electrical stimulation was repeated before, immediately after, and 5 and 10 minutes following a 3-minute accelerated chewing task. This task consisted of chewing 1.5g of a tough chewing gum at 1.5 times the subject’s natural chewing rate and in 18 cases, muscle fatigue and/or pain were reported by the subjects. Results: Following stimulation at intensities that were described as sharp or painful, all the subjects showed both a suppression of the masseter EMG and a reduction of biting force. When analysing the maximum responses in each subject, the mean reduction in the EMG inhibition was to 15.78 ± 14.4% and 10.39 ± 7.92% of the baseline (for the ipsi- and contra-lateral EMGs respectively), whereas the biting force was reduced only to 83.98 ± 11.04% of baseline (+ S.D.). The latencies of onset of these responses were: 38.17 ± 3.58ms, 38.97 ± 4.49ms and 51.83 ± 6.23ms respectively. The response observed in the force record was weaker than in that observed in either EMG (Paired t tests, P < 0.005 in both cases). When applying double stimuli, it was found that the prolongation of the EMG inhibitory jaw reflex (to 144.70 ± 46.93% of the control level) evoked by double stimulation of the upper lip (with a 10 ms inter-stimulus interval) resulted in a greater increase in the depth of the accompanied relaxation (to 223.63 ± 70.88% of that seen in the control responses) compared to a relatively smaller increase in the duration of the relaxation (to 128.32 ± 27.23% of that seen in the control responses). Following the accelerated chewing task, 17 out of 22 subjects reported pain and/or fatigue in one or both of the masseter muscles. The integral for the bite force relaxation significantly decreased in size immediately following the conditioning procedure (to 76.04 ± 35.63% of the control level, P = 0.014; single sample t-test with Bonferroni correction, test value 100). Conclusion: The inhibitory jaw reflex evoked by stimulation of the human lip can be demonstrated mechanically as well as electromyographically although the mechanical version of the response appears less marked. In addition to that, the onset of reflex relaxation in bite force lags several milliseconds behind the corresponding reductions in electromyographic activity. The depth of force relaxation can be increased by increasing the duration of EMG recorded inhibitory reflex. Finally, the results from a chewing task suggest that induced acute pain and/or fatigue cause clear changes in the mechanical manifestation of this inhibitory jaw reflex.
7
Johnsen, Skjalg E. "Human periodontal mechanoreceptors : functional properties and role in jaw motor control /." Stockholm, 2005. http://diss.kib.ki.se/2005/91-7140-321-3/.
Full text
8
De, Loubens Clément. "Compréhension et modélisation des phénomènes physiques régissant la libération des stimuli orosensoriels." Phd thesis, AgroParisTech, 2010. http://pastel.archives-ouvertes.fr/pastel-00560501.
Full textAbstract:
La compréhension et la modélisation des phénomènes régissant la libération des stimuli orosensoriels durant la consommation d'un aliment doit permettre de respecter des critères de conception à la fois nutritionnels et organoleptiques. Un modèle de libération du sel au cours de la mastication a été développé pour des produits " solides ". La déstructuration du produit a été appréhendée en terme de génération de surface de contact entre le produit et la salive qui gouverne les transferts de sel. La surface de contact a été considérée comme étant le produit de deux fonctions. La première est reliée au sujet et est fonction de son efficacité masticatoire. La seconde est reliée au produit et dépend de ses propriétés de déstructuration qui peuvent être déterminées par des tests in vitro. Durant la phase pharyngée, la biomécanique de la déglutition gouverne l'enduction des muqueuses par le bol alimentaire et ainsi la libération des composés d'arôme présents dans cette couche. Ces phénomènes sont régis par un écoulement en film mince, stationnaire, dans un contact élastohydrodynamique mou dont la cinématique équivaut à un processus d'enduction par des cylindres contrarotatifs lubrifiés par de la salive. Deux régimes ont été distingués. Lorsque le film de salive est fin, la viscosité du bol alimentaire a un grand rôle sur l'enduction et la libération des composés d'arôme. Lorsque le film de salive est épais, le bol est dilué par la salive durant le processus de déglutition et sa viscosité a un faible effet sur l'enduction et la libération des composés d'arôme. Ce second régime permet d'expliquer l'origine physique d'observations in vivo concernant la libération des composés d'arôme.
Books on the topic "Mechanical mastication"
1
Grandhe, Radhika P., Matthew Valeriano, and Dmitri Souza. Mechanical Chronic Jaw Pain. Oxford University Press, 2018. http://dx.doi.org/10.1093/med/9780190271787.003.0003.
Full textAbstract:
Mechanical jaw pain and temporomandibular joint (TMJ) disorders are the most common causes of nondental orofacial pain. The pain can originate from the joint structures or from the muscles of mastication. Diagnosis is based predominantly on the clinical history and exam findings, but imaging is indicated in certain circumstances. Secondary causes of chronic jaw pain must be sought out and meticulously ruled out. Patients presenting with TMJ pain have a high prevalence of fibromyalgia and other chronic pain conditions. Multidisciplinary treatment involving medications, minimizing parafunctional habits, oral splints, physical therapy, psychotherapy, and injections forms the cornerstone of management of this complex condition. Surgery is indicated in select conditions, such as ankylosis of the joint or tumors.
Book chapters on the topic "Mechanical mastication"
1
Katherine, E., and Marianne Defernez. "Relating Surface Electromyograms of the Facial Muscles During Mastication to the Mechanical and Sensory Properties of Foodstuffs." In Applications of EMG in Clinical and Sports Medicine. InTech, 2012. http://dx.doi.org/10.5772/26798.
Full text
2
Heath, M. R. "The basic mechanics of mastication: man's adaptive success." In Feeding and the Texture of Food, 143–66. Cambridge University Press, 1991. http://dx.doi.org/10.1017/cbo9780511600555.008.
Full textConference papers on the topic "Mechanical mastication"
1
Guessasma, S., and G. Della Valle. "Exploring mastication of cellular solids and assessment of mechanical behaviour using finite elements calculation." In 13th World Congress of Food Science & Technology. Les Ulis, France: EDP Sciences, 2006. http://dx.doi.org/10.1051/iufost:20061055.
Full text
2
Bani-Hani, Muath, and M. Amin Karami. "Power Generation From Mastication Forces Using a Smart Tooth." In ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/detc2016-60518.
Full textAbstract:
The batteries of the current pacing devices are relatively large and occupy over 60 percent of the size of pulse generators. Therefore, they cannot be placed in the subtle areas of human body. In this paper, the mastication force and the resulting tooth pressure are converted to electricity. The pressure energy can be converted to electricity by using the piezoelectric effect. The tooth crown is used as a power autonomous pulse generator. We refer to this envisioned pulse generator as the smart tooth. The smart tooth is in the form of a dental implant. A piezoelectric vibration energy harvester is designed and modeled for this purpose. The Piezoelectric based energy harvesters investigated and analyzed in this paper initially includes a single degree of freedom piezoelectric based stack energy harvester which utilizes a harvesting circuit employing the case of a purely resistive circuit. The next step is utilizing and investigating a bimorph piezoelectric beam which is integrated/embedded in the smart tooth implant. Mastication process causes the bimorph beam to buckle or return to unbuckled condition. The transitions result in vibration of the piezoelectric beam and thus generate energy. The power estimated by the two mechanisms is in the order of hundreds of microwatts. Both scenarios of the energy harvesters are analytically modeled. The exact analytical solution of the piezoelectric beam energy harvester with Euler-Bernoulli beam assumptions is presented. The electro-mechanical coupling and the geometric nonlinearities have been included in the model for the piezoelectric beam.
3
Mishra, Dhaneshwar, Seung-Hyun Yoo, Chang Yeong Park, and Jeong Ung Rak. "Evaluation of Fracture Toughness of Human Dentine-Enamel Junction (DEJ) by Finite Element Analysis." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-10874.
Full textAbstract:
Human teeth system is one of the most important organs, plays vital role in mastication process. It consist 3 layers, outer hard and brittle cover enamel and porous dentine separated by very thin interfacial region called Dentine Enamel Junction (DEJ) or crown dentine. Dentine and enamel has almost isotropic material property while DEJ has different microstructure near enamel and dentine represented by functionally graded microstructure. Experimental evidences show that the crack initiated in the hard enamel region grows towards the crown dentine, it starts healing after 10–15 micron. Finite element analysis has been carried out and fracture toughness has been evaluated for layered model of human teeth with crack initiated at enamel region grows towards DEJ with its healing capabilities and graded structure. Comparison of the result with experimental value reported in literature shows acceptable matching suggests; FE results can be taken as basis for estimating Fracture toughness of human teeth system especially at interface of Enamel and Dentine, the DEJ.
4
Chun, Keyoung Jin, Hyun Ho Choi, and Jong Yeop Lee. "A Study of the Mechanical Role of Enamel and Dentin in Human Teeth." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-86831.
Full textAbstract:
The dental hard tissues of a tooth are combined of enamel and dentin together. The enamel protects the dentin and comes in direct contact with food during mastication. Bite force is expressed as compression force. The purpose of this study is to identify the primary roles of enamel and dentin during mastication by analyzing their mechanical properties and hardness. Healthy human teeth (age: 19.3 ± 4.1) were used as specimens for mechanical tests. The teeth, which underwent epoxy resin molding, were machine cut to make 10 enamel specimens, 10 dentin specimens and 10 enamel–dentin composite (ED) specimens of 1.2 mm × 1.2 mm × 3.0 mm (Width × Height × Length) in size. Compression tests were conducted using a micro-load system at 0.1 mm/min test speed. Teeth surface hardness (HV) was measured by a Vickers diamond indenter with a 300g indentation load. Data were obtained from 4 points on each enamel specimen and 4 points on each dentin specimen. The strain (%), stress (MPa) and modulus of elasticity (E, MPa) of the specimens were obtained from compression tests. The MAX. strain of the enamel, dentin and ED specimens were 4.5 ± 0.8 %, 11.9 ± 0.1 % and 8.7 ± 2.7 %, respectively. The MAX. stress of the enamel, dentin and ED specimens were 62.2 ± 23.8 MPa, 193.7 ± 30.6 MPa and 126.1 ± 54.6 MPa, respectively. The E values of the enamel, dentin and ED specimens were 1338.2 ± 307.9 MPa, 1653.7 ± 277.9 MPa and 1628.6 ± 482.7 MPa, respectively. The E of the dentin specimens was the highest and the E of the enamel specimens was the lowest, but the E values of all specimens was not significantly different in the T-test (P > 0.1). The measured hardness value of the enamel specimens (HV = 274.8 ± 18.1) was about 4.2 times higher than that of the dentin specimens (HV = 65.6 ± 3.9). Because of the values of MAX. stress and MAX. strain of the enamel specimens, the enamel specimens tended to fracture earlier than the dentin and ED specimens; therefore, enamel was considered to be more brittle than dentin and ED. Enamel is a harder tissue than dentin based on their measured hardness values. Therefore, enamel has a higher wear resistance, making it suitable for grinding and crushing, whereas dentin has a higher force function, making it suitable for abutment against bite force.
5
Zaylor, William, Betty Sindelar, and John R. Cotton. "Finite Element Analysis Demonstrates Splinting in the Porcine Mandibular Condyle Causes Changes in Bone Volume Fraction and Stiffness Anisotropy." In ASME 2012 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/sbc2012-80311.
Full textAbstract:
Currently about 10 million Americans report signs and symptoms of TMJ dysfunction. One form of treatment for TMJ dysfunction is dental splints which reorient the jaw during mastication. This presumably changes the direction, magnitude and location of mechanical loads on the mandibular condyle of the temporomandibular joint (TMJ). The precise nature of load changes and their effect on the underlying condylar trabecular bone have not been reported.
6
Hedjazi, Lotfi, Christophe L. Martin, Sofiane Guessasma, Guy Della Valle, and Rémy Dendievel. "Application of Discrete Element Simulation to the Crushing of a Food Biopolymer Foam for Mastication Modelling." In ASME 2012 11th Biennial Conference on Engineering Systems Design and Analysis. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/esda2012-82953.
Full textAbstract:
The fragmentation behaviour of brittle airy cereal foods is studied both numerically and experimentally. The food item is subjected to severe compression until densification stage. Experimental evidence of typical cellular material behaviour is pointed out by elasticity, cell collapse and densification regimes. Using an accurate description of the cellular structure determined by X-ray tomography, a numerical approach based on discrete element method is proposed in order to better explain the resulting fragmentation. The approach allows to reproduce the deformation stages and predicted results show good agreement with experimental mechanical responses, in terms of maximum force. Moreover, large size fragments are found to form as a consequence of small rupture events.
7
Jeng, Yeau-Ren, Chien-Ping Mao, Tsung-Ting Lin, and Dar-Bin Shieh. "Contact Mechanics Study in Biotribology: A Tissue Engineering Example." In ASME/STLE 2007 International Joint Tribology Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ijtc2007-44141.
Full textAbstract:
The study of biotribology attracts increasingly attention because it holds great promise to have profound impact on the way people live their lives. This study presents two cases of contact mechanics study on tissue engineering: one in soft tissue and the other one in hard tissue. In the study of soft tissue, we conducted a theoretical investigation into the effect of particle on the adhesion of a biological nanostructure system. Based on a three-body contact model and JKR theory our results show that geckos’ spatulas provides robust adhesions even with trapped particles in the interface. In the case of hard tissue, we utilized nanoindentation technique to characterize the mechanical property and tribology behavior of calcium fluoride-like deposits on human tooth. The low nanohardness and high nano-wear depth characteristics of the surface deposits identified in this study account for the natural loss of the surface deposits days or weeks after topical fluoride treatment as a result of daily brushing and mastication.
8
Shanmuga Sundaram, Karibeeran, Gurusami Kiliyappan, and Senthil Kumaran Selvadurai. "The Influence of Laser Irradiation Parameters on Tribological Behaviour of Commercially Pure Titanium for Dental Prostheses." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-66524.
Full textAbstract:
Laser shock peening (LSP) is one of the innovative technique that produces a compressive residual stress on the surface of metallic materials, thereby significantly increasing its fatigue life in applications where failure is caused by surface-initiated cracks. The specimens were treated with laser shock waves with different processing parameters, and characterization studies were made on treated specimens. The purpose of the present study was to investigate the influence of Nd:YAG laser on commercially pure titanium (CP-Ti) used in prosthetic dental restorations. The treatment influenced change in microstructure, micro hardness, surface roughness, and wear resistance characteristics. Though CP-Ti is considered as an excellent material for dental applications due to its outstanding biocompatibility, it is not suitable when high mastication forces are applied. In the present study, pulsed Nd:YAG laser surface treatment technique was adopted to improve the wear resistance of CP-Ti. The wear test pin specimens of CP-Ti were investment cast with centrifugal titanium casting machine. The wear properties of specimens were evaluated after LSP on a “pin-on-disc” wear testing tribometer, as per ASTM G99-05 standards. The results of the wear experiment showed that the treated laser surface has higher wear resistance, micro hardness, and surface roughness compared to as-cast samples. The improvement of wear resistance may be attributed due to grain refinement imparted by LSP processes. The microstructure, wear surfaces, wear debris, and morphology of the specimen were analyzed by using optical electron microscope, scanning electron microscope, and X-ray diffraction (XRD). The data were compared using ANOVA and post-hoc Tukey tests. The characteristic change resulted in increase in wear resistance and decrease in wear rate. Hence, it is evident that the more reliable and removable partial denture metal frameworks for dental prostheses may find its applications.
9
Agostinho Hernandez, Bruno, Alexander Paterno, Edson Antonio Capello Sousa, João Paulo de Oliveira Freitas, and Cesar Renato Foschini. "Fatigue Analysis of Dental Prostheses by Finite Element Method (FEM)." In ASME 2015 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/imece2015-51911.
Full textAbstract:
Introduction and Objectives: The dental prostheses are typical biomechanical structures because they have the objective to restore the mastication functions and are responsible for replacing the original tooth that was damaged. In the last few years, many studies have been done and big achievements have been noticed in this area. However, clinical studies and experimental procedures for these conditions are sometimes impractical, due to the biological nature of these components and the difficult to reproduce and to analyze such conditions. Moreover, it involves complex geometries, loads and mechanical behaviors, which analytical solution is very difficult to achieve. For these reasons, many researchers have applied the Finite Element Method (FEM). This method allows the evaluation of non-linear situations (e.g. biomechanical interactions) with complex geometries where experimental tests are usually difficult to be conducted. Furthermore, the uses of this method allow failure evaluation and it forecast occurrence. Like any mechanical structure, prostheses are sensible to failures. The cyclic nature of the loading that components are exposed means that fatigue failures are the type of failure which needs more attention in these kinds of structures. Therefore, this project aims to develop a tridimensional finite element model of dental prosthesis in order to evaluate the fatigue problem. Methods: A geometric model from a single dental prosthesis compounded by an implant, an abutment screw, an abutment, a fixation’s screw and a crown will be generated from Micro CT and scanning data. Then, the geometry will be exported to finite element software where a finite element model will be created. After these steps, boundaries conditions will be applied and simulations will be done. Finally, the simulation results will be analyzed. Results: The results from fatigue simulations and analysis demonstrated that abutment screw will have a finite life in most of the analyzed cases, and the fixation screw will be an infinite life. Conclusion: The results obtained illustrate the efficiency of Finite Element Method on simulating the biomechanical conditions, mainly in dental prostheses. In this study, the fatigue conditions were explored and analyzed. Finally, the knowledge about this problem could be improved.