Journal articles: 'Mechanical mastication'

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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KAMATANI, Naoya, and Hiroshi MIZUNUMA. "Swallowing and mastication from a view point of mechanical engineering." Proceedings of Mechanical Engineering Congress, Japan 2016 (2016): S0530103. http://dx.doi.org/10.1299/jsmemecj.2016.s0530103.

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Vaccioli, Kleber, Samuel Marcio Toffoli, and Ticiane Sanches Valera. "Influence of the Order of Incorporation of Sulfur in the Mechanical Properties of Vulcanized Nr Compounds." Materials Science Forum 1012 (October 2020): 62–66. http://dx.doi.org/10.4028/www.scientific.net/msf.1012.62.

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The objective of this work was to evaluate the influence of the order of sulfur addition on the mechanical properties of vulcanized natural rubber compounds. The addition of sulfur was carried out by two methodologies: (I) sulfur was added at the beginning of the mastication process, and (II) sulfur was added at the end of the mixing process. The compounds were obtained in open cylinder, and vulcanized in a press at 150°C. The vulcanization parameters were determined by rheometry, where as the mechanical properties were evaluated by testing samples for their tensile strength, tear strength, resilience, and Shore-A hardness. The dimensional stability of the vulcanized samples was also evaluated experimentally, by comparing specimens not heat-treated to those submitted to 100°C for 4 hours. Comparing the results of method (I) to method (II), the results, indicate that the addition of sulfur at the beginning of the mastication process (method I) yielded increases of 20 and 11% in tensile strength and tear strength, respectively, followed by a 9% increase in hardness, and 6% in resilience, without significant losses in maximum elongation. The dimensional stability test showed a reduction of 75% in the contraction for the vulcanized samples which had sulfur addition at the beginning of the mastication process of the unvulcanized NR rubber.

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Frayne, Ryan J., Marvin Schwartz, and James P. Dickey. "A Mastication Mechanism Designed for Testing Temporomandibular Joint Implants." Applied Bionics and Biomechanics 9, no. 3 (2012): 241–47. http://dx.doi.org/10.1155/2012/324034.

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The development of temporomandibular joint implants has involved simplified mechanical tests that apply pure vertical forces or pure rotational movements to the implant. The aim of this study was to develop a biological based mastication mechanism and conduct preliminary testing of a novel temporomandibular joint implant. The mechanism was designed to mimic temporomandibular joint loads by performing compression and anterior/posterior translation. Pilot testing was performed on six implant/joint specimens for seven consecutive hours, completing approximately 22,000 cycles at a frequency of approximately 1 Hz. Each cycle had a joint compression phase (67.3 N over 0.15 s) followed by a translation phase (8.67 N over 0.43 s) that was similar to joint loads/motions that have been reported in vivo. This new mastication mechanism incorporates both anatomical and mechanical variability. The use of biological specimens is an important approach that can help bridge the gap between traditional synthetic implant materials/mechanical testing andin vivotesting.

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Bikos, D., G. Samaras, P. Cann, M. Masen, Y. Hardalupas, C. Hartmann, J. Vieira, and M. N. Charalambides. "Effect of micro-aeration on the mechanical behaviour of chocolates and implications for oral processing." Food & Function 12, no. 11 (2021): 4864–86. http://dx.doi.org/10.1039/d1fo00045d.

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Effect of micro-aeration on the mechanical response of chocolate is investigated and the data are used to calibrate a viscoplastic constitutive model. The link between the laboratory measurements, in vivo mastication data, and texture is highlighted.

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Naser-ud-Din, S., P. F. Sowman, H. Dang, and K. S. Türker. "Modulation of Masseteric Reflexes by Simulated Mastication." Journal of Dental Research 89, no. 1 (December 4, 2009): 61–65. http://dx.doi.org/10.1177/0022034509352842.

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It is well-known that limb muscle reflexes are modulated during human movements. However, little is known about the existence of equivalent masticatory muscle reflex modulation. We hypothesized that masticatory reflexes would be modulated during chewing so that smooth masticatory movements occur. To examine this hypothesis, we studied the modulation of inhibitory reflexes evoked by periodontal mechanoreceptor activation and of excitatory reflexes evoked by muscle spindle activation during simulated mastication. In 28 participants, 1- and 2-N mechanical taps were delivered to the incisor. Reflex responses to these taps were examined in the average masseteric electromyogram. To differentiate between periodontal mechanoreceptor- and muscle-spindle-mediated reflex components, we performed experiments prior to, and in the presence of, periodontal anesthesia. Both periodontal mechanoreceptor and muscle spindle reflexes were reduced during simulated masticatory movements.

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Mao, Qian, Yonghai Sun, Jumin Hou, Libo Yu, Yang Liu, Chao Liu, and Na Xu. "Relationships of Image Texture Properties with Chewing Activity and Mechanical Properties during Mastication of Bread." International Journal of Food Engineering 12, no. 4 (June 1, 2016): 311–21. http://dx.doi.org/10.1515/ijfe-2015-0309.

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Abstract The objective of this study was to investigate the relationships of image texture properties with chewing behaviors, and mechanical properties during mastication of bread. Gray-level gradient co-occurrence matrix (GGCM) was used to process the images of boluses. The chewing behaviors were recorded by electromyography (EMG), and the mechanical properties were measured by texture analyzer. The results showed that among the texture features, the inverse difference moment (IDMGGCM) was selected as the main parameter to describe the decomposition of boluses. IDMGGCM was positively related to the weight gain (r = 0.865, p < 0.01), negatively correlated with hardness (r = –0.835, p <0.01) and EMG activity per cycle (r = –0.767, p < 0.01). GGCM is an effective texture analysis method that could correctly identify 70.1–80.8 % of food bolus images to the corresponding chewing cycles. This study provided a new clue for texture analysis of bread bolus images and offered data revealing the bolus property changes during the mastication of bread.

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Black, Devin E., Mary A. Arthur, Wendy Leuenberger, David D. Taylor, and Jeffrey F. Lewis. "Alteration to Woodland Structure through Midstory Mastication Increased Fuel Loading and Cover of Understory Species in Two Upland Hardwood Stands." Forest Science 65, no. 3 (January 29, 2019): 344–54. http://dx.doi.org/10.1093/forsci/fxy066.

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Abstract The contemporary decline of open woodlands in the eastern United States has prompted land managers to implement management prescriptions that encourage landscape and habitat diversity, often using mechanical thinning and prescribed fire as tools to alter stand structure. To increase habitat diversity and restore natural processes, a long-term oak woodland restoration project was planned for two upland hardwood stands in the Daniel Boone National Forest, Kentucky, United States. As an initial phase of restoration, we examined the effects of midstory mastication on stand structure, understory vegetation response, and fuels. The mastication treatment reduced stem density and basal area of trees ≤7.9 in. (20.1 cm) dbh by 69 percent and 47 percent, respectively, encouraged vigorous stump/root sprouting, and increased ground cover of forbs (204 percent) and native graminoids (253 percent) the first year on treated plots. Additionally, mastication created a variable cover of woody mulch on the forest floor and increased 1-h and 100-h time-lag fuels compared with controls. In year 2, Microstegium vimineum (invasive grass) cover increased by 700 percent on treated plots. This study imparts novel information on the mastication of upland hardwoods to benefit land managers in directing future treatments to shape desired stand structures and compositions, and increase landscape heterogeneity.

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Narayanan, Madusudanan Sathia, Srikanth Kannan, Xiaobo Zhou, Frank Mendel, and Venkat Krovi. "Parallel Architecture Manipulators for Use in Masticatory Studies." International Journal of Intelligent Mechatronics and Robotics 1, no. 4 (October 2011): 100–122. http://dx.doi.org/10.4018/ijimr.2011100106.

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There is considerable scientific and commercial interest in understanding the mechanics of mastication. In this paper, the authors develop quantitative engineering tools to enable this process by: (i) designing a general purpose mastication simulator test-bed based on parallel architecture manipulator, capable of producing the requisite motions and forces; and (ii) validating this simulator with a range of test-foods, undergoing various mastication cycles under controlled and monitored circumstances. Such an implementation provides a test bed to quantitatively characterize the mastication based on “chewability index”. Due to the inherent advantages of locating actuators at the base (ground) in terms of actuator efforts and structural rigidity as well as benefits of using prismatic sliders compared to revolute actuators, the 6-P-U-S system was chosen. A detailed symbolic kinematic analysis was then conducted. For the practical implementation of the test-bed, the analytical Jacobian was examined for singularities and the design was adapted to ensure singularity free operation. A comprehensive parametric study was undertaken to obtain optimal design parameters for desired workspace and end effector forces. Experiments captured jaw motion trajectories using the high speed motion capture system which served as an input to the hardware-in-the-loop simulator platform.

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Kobziar, Leda N., Joe R. McBride, and Scott L. Stephens. "The efficacy of fire and fuels reduction treatments in a Sierra Nevada pine plantation." International Journal of Wildland Fire 18, no. 7 (2009): 791. http://dx.doi.org/10.1071/wf06097.

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Plantations are the most common means of reforestation following stand-replacing wildfires. As wildfires continue to increase in size and severity as a result of fire suppression or climate change, establishment of plantations will likely also increase. Plantations’ structural characteristics, including dense, uniform spacing and abundant ladder fuels, present significant wildfire hazards. Large-scale fuels reduction techniques may be necessary to reduce potential fire behavior in plantations and to protect surrounding forests. In the present study, four different manipulations aimed at reducing potential fire behavior in a Sierra Nevada pine plantation are compared. The treatments include: mechanical shredding, or mastication, of understorey vegetation and small trees; mastication followed by prescribed fire; fire alone; and controls. Fire behavior modeling shows that mastication is detrimental whereas prescribed fire is effective in reducing potential fire behavior at moderate to extreme weather conditions. Predicted fire behavior was compared with actual values from the prescribed burns in an effort to explore the limitations of fire modeling. Fire behavior predictions were similar to field observations in the more structurally homogeneous stands, but differed greatly where mastication created forest openings and patchy fuels distributions. In contrast to natural stands, the homogeneity of pine plantations make the results of the present work applicable to other regions such as the south-eastern US, where similar fuels reduction techniques are used to increase fire-resistance and stand resilience.

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Reemts, Charlotte M., and David A. Cimprich. "Restoring Early-Successional Shrubland Habitat for Black-Capped Vireos using Mechanical Mastication." Natural Areas Journal 34, no. 4 (October 2014): 400–407. http://dx.doi.org/10.3375/043.034.0402.

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Ali, Benaissa, El Bahri Ould Chikh, Hadj Miloud Meddah, Ali Merdji, and Bel abbes Bachir Bouiadjra. "Effects of overloading in mastication on the mechanical behaviour of dental implants." Materials & Design 47 (May 2013): 210–17. http://dx.doi.org/10.1016/j.matdes.2012.12.019.

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Kreye, Jesse K., J. Morgan Varner, and Eric E. Knapp. "Moisture desorption in mechanically masticated fuels: effects of particle fracturing and fuelbed compaction." International Journal of Wildland Fire 21, no. 7 (2012): 894. http://dx.doi.org/10.1071/wf11077.

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Mechanical mastication is increasingly used as a wildland fuel treatment, reducing standing trees and shrubs to compacted fuelbeds of fractured woody fuels. One major shortcoming in our understanding of these fuelbeds is how particle fracturing influences moisture gain or loss, a primary determinant of fire behaviour. To better understand fuel moisture dynamics, we measured particle and fuelbed drying rates of masticated Arctostaphylos manzanita and Ceanothus velutinus shrubs, common targets of mastication in fire-prone western USA ecosystems. Drying rates of intact and fractured particles did not differ when desorbing at the fuelbed surface, but these particles did dry more rapidly than underlying fuelbeds. Average response times of 10-h woody particles at the fuelbed surfaces ranged from 16 to 21 h, whereas response times of fuelbeds (composed of 1-h and 10-h particles) were 40 to 69 h. Response times did not differ between fuelbeds composed of fractured woody particles and fuelbeds composed of intact particles (P = 0.258). Particle fracturing as a result of mastication does not affect the drying rate, but the longer-than-expected response times of particles within fuelbeds underscores the needs to better understand fuel moisture dynamics in these increasingly common fuels.

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Wongpreedee, Thapanee, Karine Mougin, and Taweechai Amornsakchai. "Effect of Mastication Time on the Properties of Stearic Acid Coated Pineapple Leaf Fiber Reinforced Natural Rubber." Key Engineering Materials 824 (October 2019): 100–106. http://dx.doi.org/10.4028/www.scientific.net/kem.824.100.

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Pineapple leaf fiber (PALF) having an average diameter and length of about 4 μm and 6 mm, respectively, was used as reinforcing element for natural rubber (NR) composites. PALF was coated with different amount of stearic acid at 10, 30 and 50 wt% of PALF. PALF-NR composites containing two levels of PALF at 5 and 10 part per hundred rubber (phr) were prepared in a two roll mill. Mastication times of 2, 4 and 8 min were used. Tensile stress-strain curves and fracture surfaces of both untreated PALF and stearic acid coated PALF (SA-PALF) reinforced NR prepared with different mastication times were compared. At low level of PALF where aggregation was not a problem, stearic coating had adverse effect on mechanical properties due to the slippery PALF-rubber interface. At high level of PALF, the coating gave composites with higher tensile strength and strain at break. Moreover, tensile strength and strain at break increased with increasing mastication time. This indicates that stearic acid coating reduces the formation of PALF aggregations and allows PALF to work effectively.

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Kreye, Jesse K., and Leda N. Kobziar. "The effect of mastication on surface fire behaviour, fuels consumption and tree mortality in pine flatwoods of Florida, USA." International Journal of Wildland Fire 24, no. 4 (2015): 573. http://dx.doi.org/10.1071/wf14186.

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Mastication of understorey shrubs and small trees to reduce fire hazard has become a widespread forest management practice, but few empirical studies have quantified the effects of this mechanical treatment on actual fire behaviour and fire effects at the stand scale. We conducted experimental burns in masticated pine flatwoods with palmetto/gallberry understories, a common ecosystem of the Southern US Coastal Plain. Fire behaviour (flame height, rate of spread) and fire effects were compared between treated and untreated sites burned in the typical winter prescribed burning season. Mastication effectively reduced flame heights by 66%, but recovering shrubs (cover, height) influenced fire behaviour within six months following treatment, suggesting time-limited effectiveness. Trees had less crown scorch and bole char in masticated sites, but tree mortality was minimal on both treated and untreated sites. Consumption of masticated fuel was substantial across both treatments, but little duff was consumed under the moist soil conditions. When burning is conducted soon after treatment, mastication may effectively reduce fire behaviour in pine flatwoods sites, but the duration of treatment efficacy remains unclear.

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Nikolov, V. V., D. M. Korol, D. D. Kindiy, and M. D. Korol. "DETERMINATION OF CHEWING EFFICIENCY IN PATIENTS WITH RESTORED TOOTH CROWN PART." Ukrainian Dental Almanac, no. 1 (March 23, 2021): 64–68. http://dx.doi.org/10.31718/2409-0255.1.2021.10.

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Supporting teeth preservation at the restoration of dentition defects with the help of fixed porcelain fused metal dentures is considered one of the most important issues of prosthodontics. Margin line preparation strategies are still disputable nowadays. In most cases preparation is confined to the ledge creation. Its function is to provide a smooth transition of orthopedic restoration to a tooth root and prevent the traumatization of marginal paradontium. These issues are gaining a momentum when the possibility of manufacturing fixed prosthesis with the use of partially or completely ruined teeth with the preserved root as a support appears. Since the opportunities of thermal method for gingiva retraction and marginal line formation around the supporting teeth are not studied enough in modern scientific sources, our research aims to define the mastication efficiency state in patients of sample groups after the fixation of dentures on the supporting teeth prepared for prosthesis with the help of diathermocoagulation and mechanical retraction. The authors of the article have determined the mastication efficiency in the patients with the restored tooth crown. Altogether 54 patients of two sample groups aged from 20 to 60 years and above with completely ruined tooth crowns were examined. Their soft tissues around the supporting teeth were prepared for the fixed prosthesis manufacturing. The first sample group involved 29 patients that made up 53.7% of general studied population. Their supporting teeth gingiva margins were retracted with the help of diathermocoagulation while preparing them for the fixed dentures. While the gingiva margins of the patients of the second sample group, consisting of 25 people (46.3% of general studied population), were retracted with the help of cotton Ultrapak cord, produced by Ultradent (the USA). It is offered in several size options. Mastication efficiency state after prosthesis was determined with the help of mastication test (Ukrainian Utility Patent # 94841). In this case, mastication index was the main diagnostic tool. It was received with the help of computer analysis of digital samples in software “Adobe Photoshop Extended”. The analysis of the dynamics of mastication test indices of the patients of sample group 1 delivered typical results. In a week after the fixation of fixed porcelain fused metal dentures, the reduction of the mean value of mastication test index by 0.2 was fixed. The verification of these changes according to the statistical significance showed positive result (at p = 0.0004). At the same time, the verification of the changes, occurred during the period from the 7th to the 30th day after the fixation of dentures in patients of sample group 1, with the help of Wilcoxon test showed that at p = 0.9 the reduction of the mean value to 5.148 had no statistical significance. While the dynamics of mastication test changes in sample group 2 looked as follows. The reduction of the mean values of mastication test index from 5.184 to 5.112 was observed. So, the spread between the values received before the retraction and in seven days after crown fixation made up 0.072. The conducted statistical verification of these changes (at p = 0.01) proved their statistical significance. In contrast, the collation of the indices received after seven days of denture fixation and in 30-days period after it (from 5.112 to 5.132) at p = 0.961 demonstrated changes at the level of statistical error. According to the received research results, prosthesis with the fixed porcelain fused metal dentures promotes patients’ mastication efficiency restoration. That is traced in the reduction of the mastication test index values received after the 7th day of crown fixation in both sample groups. It should be noted here, that statistically significant difference between the indices of the patients of sample group 1 and 2 was not found. On the 30th day of denture fixation, mastication efficiency indices remained almost the same.

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Pallares Pallares, Andrea, Bram Loosveldt, Solomon N. Karimi, Marc Hendrickx, and Tara Grauwet. "Effect of process-induced common bean hardness on structural properties of in vivo generated boluses and consequences for in vitro starch digestion kinetics." British Journal of Nutrition 122, no. 04 (July 3, 2019): 388–99. http://dx.doi.org/10.1017/s0007114519001624.

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AbstractIn the present study, we evaluated the effect of process-induced common bean hardness on structural properties ofin vivogenerated boluses and the consequences forin vitrostarch digestion. Initially, the impact of human mastication on the particle size distribution (PSD) of oral boluses from common beans with different process-induced hardness levels was investigated through a mastication study. Then the effect of structural properties of selected boluses onin vitrostarch digestion kinetics was assessed. For a particular process-induced hardness level, oral boluses had similar PSD despite differences in masticatory parameters between participants of the mastication study. At different hardness levels, a clear effect of processing (P<0·0001) was observed. However, the effect of mastication behaviour (P=0·1141) was not significant. Two distinctive fractions were present in all boluses. The first one was a cotyledon-rich fraction consisting of majorly small particles (40–125 µm), which could be described as individual cells based on microscopic observations. This fraction increased with a decrease in process-induced hardness. The second fraction (>2000 µm) mostly contained seed coat material and did not change based on hardness levels. Thein vitrostarch digestion kinetics of common bean boluses was only affected by process-induced hardness. After kinetic modelling, significant differences were observed between the reaction rate constant of boluses generated from the hardest beans and those obtained from softer ones. Overall this work demonstrated that thein vitronutritional functionality of common beans is affected to a greater extent by structural properties induced by processing than by mechanical degradation in the mouth.

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Kim, Hee-Sun, Jae-Yong Park, Na-Eun Kim, Yeong-Soo Shin, Ji-Man Park, and Youn-Sic Chun. "Finite element modeling technique for predicting mechanical behaviors on mandible bone during mastication." Journal of Advanced Prosthodontics 4, no. 4 (2012): 218. http://dx.doi.org/10.4047/jap.2012.4.4.218.

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Panagiotopoulou, Olga, and Samuel N. Cobb. "The mechanical significance of morphological variation in the macaque mandibular symphysis during mastication." American Journal of Physical Anthropology 146, no. 2 (August 8, 2011): 253–61. http://dx.doi.org/10.1002/ajpa.21573.

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Pamungkas, Putri Bintang, Shanty Chairani, and Rani Purba. "Performance of Mastication in Menopausal Women in Palembang." Jurnal Kesehatan Gigi 6, no. 2 (December 31, 2019): 113–17. http://dx.doi.org/10.31983/jkg.v6i2.5487.

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Mastication is the mechanical process of breaking down food in oral cavity. The mastication system involves several components, including saliva and alveolar bone. Salivary flow rate and alveolar bone mineral density have been reported decreased in menopausal women due to the impact of declining estrogen levels. Menopause is the permanent cessation of menstruation resulting from the loss of ovarian follicular activity. The aim of this study was to evaluate the masticatory performance in menopausal women in Kelurahan Talang Kelapa RW 19. This observational experimental study with cross-sectional design involved 36 women, consisting of 18 women and 18 non-menopause women. Masticatory performance was evaluated using a sieve method. Each subject was asked to chew 3 gram peanuts for 20 masticatory strokes, which that procedure was repeated for five times. Masticatory performance was measured using a sieve method which based on the assessment of the size of food particles that have been chewed and filtered over a number 10 mesh sieve. Percentage masticatory performance was obtained by dividing volume of particles passed through the filter with the volume of total particles. The masticatory performance data were analyzed statically with independent samples T test. The mean masticatory performance score was 13,71%, in menopausal women and 30,62% in non-menopausal women. It was found that masticatory performance in menopausal women was significantly lower when compared to non-menopausal women (p0,05). It may be concluded that menopause decreased the masticatory performance.

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Reed, Warren P., J. Morgan Varner, Eric E. Knapp, and Jesse K. Kreye. "Long-term changes in masticated woody fuelbeds in northern California and southern Oregon, USA." International Journal of Wildland Fire 29, no. 9 (2020): 807. http://dx.doi.org/10.1071/wf19156.

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Mechanical mastication is a fuels treatment that shreds midstorey trees and shrubs into a compacted woody fuel layer to abate fire hazards in fire-prone ecosystems. Increased surface fuel loading from mastication may, however, lead to undesirable fire intensity, long-duration flaming or smouldering, and undesirable residual tree mortality. Two major questions facing fuels managers are: how long do masticated fuels persist, and how does the composition of masticated fuelbeds change over time? To evaluate these changes, we measured 25 masticated sites with a range of vegetation, species masticated and time since treatment (1–16 years) in the western US. Seven of the 25 sites were sampled nearly a decade earlier, providing a unique opportunity to document fuelbed changes. Woody fuel loading ranged from 12.1 to 91.9Mg ha−1 across sites and was negatively related to time since treatment. At remeasured sites, woody fuel loads declined by 20%, with the greatest losses in 1- and 10-h woody fuels (69 and 33% reductions in mass respectively). Reductions were due to declines in number of particles and reduced specific gravity. Mastication treatments that generate greater proportions of smaller-diameter fuels may result in faster decomposition and potentially be more effective at mitigating fire hazard.

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Schiks, T. J., and B. M. Wotton. "Modifying the Canadian Fine Fuel Moisture Code for masticated surface fuels." International Journal of Wildland Fire 24, no. 1 (2015): 79. http://dx.doi.org/10.1071/wf14041.

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Mechanical mastication is a fuel management technique that disrupts the vertical continuity of forest fuels by shredding of trees and understory vegetation into a highly compacted surface fuel bed. Despite the increasing application of mastication to manage wildfire risk, there is little information to date on fuel moisture in masticated fuels and optimal ignition patterns for prescribed burning. We investigated the applicability of the Fine Fuel Moisture Code (FFMC), a component of the Canadian Fire Weather Index (FWI) System, in tracking the diurnal and day-to-day changes in masticated surface fuel moisture, and developed a calibration of the standard conversion between moisture content and FFMC via regression modelling. We also proposed several modifications to the FFMC model (including a solar radiation driven fuel temperature) to better estimate the fuel-specific parameters of small diameter (<1 cm) masticated surface fuels. Model validation was performed using destructive moisture content observations from a mastication treatment in west-central Alberta, Canada. A calibrated form of the moisture content to FFMC conversion produced mean error of –2.3% moisture content, and closely resembled previous FWI System calibrations for fast drying surface fuels. Our modified FFMC-based model fit well with field observations, and was capable of producing mean error of 1.0% moisture content. The fast drying that we observed highlights the need to better understand moisture dynamics of masticated fuel beds.

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Becker, Ryer, and Robert Keefe. "Prediction of Fuel Loading Following Mastication Treatments in Forest Stands in North Idaho, USA." Sustainability 12, no. 17 (August 28, 2020): 7025. http://dx.doi.org/10.3390/su12177025.

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Fuel reduction in forests is a high management priority in the western United States and mechanical mastication treatments are implemented common to achieve that goal. However, quantifying post-treatment fuel loading for use in fire behavior modeling to forecast treatment effectiveness is difficult due to the high cost and labor requirements of field sampling methods and high variability in resultant fuel loading within stands after treatment. We evaluated whether pre-treatment LiDAR-derived stand forest characteristics at 20 m × 20 m resolution could be used to predict post-treatment surface fuel loading following mastication. Plot-based destructive sampling was performed immediately following mastication at three stands in the Nez Perce Clearwater National Forest, Idaho, USA, to correlate post-treatment surface fuel loads and characteristics with pre-treatment LiDAR-derived forest metrics, specifically trees per hectare (TPH) and stand density index (SDI). Surface fuel loads measured in the stand post-treatment were consistent with those reported in previous studies. A significant relationship was found between the pre-treatment SDI and total resultant fuel loading (p = 0.0477), though not between TPH and fuel loading (p = 0.0527). SDI may more accurately predict post-treatment fuel loads by accounting for both tree number per unit area and stem size, while trees per hectare alone does not account for variations of tree size and subsequent volume within a stand. Relatively large root-mean-square errors associated with the random forest models for SDI (36%) and TPH (46%) suggest that increased sampling intensity and modified methods that better account for fine spatial variability in fuels resulting from within-stand conditions, treatment prescriptions and machine operators may be needed. Use of LiDAR to predict fuel loading after mastication is a useful approach for managers to understand the efficacy of fuel reduction treatments by providing information that may be helpful for determining areas where treatments can be most beneficial.

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Ooyama, Takahiro, Satomi Akutsu, Kazuko Ito, Tsuneo Watanabe, Kimii Yamazaki, and Kaoru Kohyama. "The Influence of Skin Processing on Mechanical and Mastication Properties of Takuan (Pickled Radish)." Nippon Shokuhin Kagaku Kogaku Kaishi 57, no. 6 (2010): 232–37. http://dx.doi.org/10.3136/nskkk.57.232.

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Ctvrtlik, Radim, and Jan Tomastik. "Wear Behavior of Hard Dental Tissues and Restorative Materials." Applied Mechanics and Materials 486 (December 2013): 72–77. http://dx.doi.org/10.4028/www.scientific.net/amm.486.72.

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Human teeth are exposed to various chemical and mechanical factors. From mechanical point of view it includes attrition, abrasion or their combination. Teeth and dental restorative materials are subjected to normal and shear loads. Therefore the contact-based stresses during mastication and teeth wear are of considerable importance. In order to study wear behavior of enamel, dentine and two dental restorative composite materials scratch test at various contact conditions was employed. Hardness and elastic modulus were measured using nanoindentation with spherical and pyramidal indenters. Residual wear tracks were observed using laser scanning confocal microscopy.

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Commisso, Maria S., Joaquín Ojeda, Juana Mayo, and Javier Martínez-Reina. "Influence of the Temporomandibular Joint in the Estimation of Bone Density in the Mandible through a Bone Remodelling Model." Mathematical Problems in Engineering 2018 (October 21, 2018): 1–14. http://dx.doi.org/10.1155/2018/7243696.

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The temporomandibular joint (TMJ) plays a key role in the distribution of stresses in the mandible during mastication and consequently in the distribution of bone density, due to the interconnection between both variables through bone remodelling. Two finite element models of the mandible were compared to study the influence of the redistribution of stresses produced by the joint: (1) a model without TMJ, but with simplified boundary conditions to replace the joint, as done in previous models; (2) a more realistic model including the articular disc and some ligaments present in the TMJ. The stresses and strains in both models were compared through the strain energy density, used in many bone remodelling models as a measure of the mechanical stimulus. An anisotropic bone remodelling model was used to simulate the behaviour of mandible bone and to estimate its density distribution. The results showed that the TMJ strongly affects the stress distribution, the mechanical stimulus, and eventually the bone density, and not only locally in the condyle, but also in the whole mandible. It is concluded that it is utterly important to include a detailed model of the TMJ to estimate more correctly the stresses in the mandible during mastication and, from them, the bone density and anisotropy distribution.

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Wang, Lin. "Biomechanical Analysis in Human Masticatory System." Applied Mechanics and Materials 249-250 (December 2012): 1294–300. http://dx.doi.org/10.4028/www.scientific.net/amm.249-250.1294.

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The necessary theoretical and methodological foundation is provided by means of which the human mastication process could be studied and reproduced in a digital dynamic way. This paper reviews previous publications and elaborates further mathematical analysis and mechanical analysis of biomechanical functions, explaining the characteristics of human mandible, Temporomandibular joints (TMJs), muscles based on clinical anatomy, and analysing the inter-relationship and inter-reflection between each component of this multi-body assembled organism.

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Kane, Jeffrey M., J. Morgan Varner, Eric E. Knapp, and Robert F. Powers. "Understory vegetation response to mechanical mastication and other fuels treatments in a ponderosa pine forest." Applied Vegetation Science 13, no. 2 (April 2010): 207–20. http://dx.doi.org/10.1111/j.1654-109x.2009.01062.x.

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Tanrattanakul, Varaporn, Pranee Bunkaew, and Nutnicha Boonlong. "Influence of Rubber Mastication on Mechanical Properties of Poly(lactic acid)—Based Thermoplastic Natural Rubber." Journal of Biobased Materials and Bioenergy 6, no. 5 (October 1, 2012): 573–79. http://dx.doi.org/10.1166/jbmb.2012.1259.

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Seavy, Nathaniel E., John D. Alexander, and Paul E. Hosten. "Bird community composition after mechanical mastication fuel treatments in southwest Oregon oak woodland and chaparral." Forest Ecology and Management 256, no. 4 (August 2008): 774–78. http://dx.doi.org/10.1016/j.foreco.2008.05.034.

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Dutzan, Nicolas, Loreto Abusleme, Hayley Bridgeman, Teresa Greenwell-Wild, Tamsin Zangerle-Murray, Mark E. Fife, Nicolas Bouladoux, et al. "On-going Mechanical Damage from Mastication Drives Homeostatic Th17 Cell Responses at the Oral Barrier." Immunity 46, no. 1 (January 2017): 133–47. http://dx.doi.org/10.1016/j.immuni.2016.12.010.

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Lovald, Scott T., Tariq Khraishi, John Wood, Jon Wagner, Bret Baack, and James Kelly. "Finite Element Analysis of Screw-Plate Systems for Fixation of Parasymphyseal Fractures of the Mandible." Journal of Mechanics 23, no. 1 (March 2007): 69–77. http://dx.doi.org/10.1017/s172771910000109x.

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AbstractFinite Element Modeling was used to compare the efficacy of common screw-plate configurations used for fixation of parasymphyseal fractures of the mandible. Measures of Von Mises stress on the screw bone interface, as well as principal strain in the reduced fracture region, were used in this comparison. This study also explored differences between orthotropic and isotropic modeling practices and compared the effect of mastication forces on both the fractured and intact halves of the mandible. The results of this analysis showed no major differences between configurations from a mechanistic point of view. This suggests that the use of any of the studied screw-plate configurations will not increase chances for post-operative complications. Furthermore, little difference is seen between analyses with either orthotropic or isotropic material properties. The inclusion of orthotropic properties can thus be avoided in future studies with similar boundary and plating conditions. Mastication ipsilateral to the fracture increases Von Mises stress 2 to 4 times, and should be avoided during early healing periods. These recommendations only apply to patients whose fractures mimic the finite-element model.

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Yang, Bin, Zheng Shi, Qun Wang, Feng Xiao, Tong-Tong Gu, Yong-Kai Yin, and Zhong-Liang Miao. "Frequency spectrum of the human head–neck to mechanical vibrations." Journal of Low Frequency Noise, Vibration and Active Control 37, no. 3 (December 20, 2017): 611–18. http://dx.doi.org/10.1177/1461348417747179.

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This study is based on a real finite element human head–neck model and concentrates on its numerical vibration characteristic. Frequency spectrum and mode shapes of the finite element model of human head–neck under mechanical vibration have been calculated. These vibration characteristics are in good agreement with the previous studies. The simulated fundamental frequency of 35.25 Hz is fairly similar to the published documents, and rarely reported modal responses such as “mastication” and flipping of nasal lateral cartilages modes, however, are introduced by our three-dimensional modal analysis. These additional modes may be of interest to surgeons or clinicians who are specialized in temporomandibular or rhinoplasty joint disorder. Modal validation in terms of modal shapes proposes a necessity for elaborate modeling to identify each individual part’s extra frequencies. Furthermore, it also studies the influence of damping on resonant frequencies and biomechanical responses. It is discovered that damping has an inverse proportionality between damping effect on natural frequency and that on biomechanical responses.

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Hisano, Masataka, and Kunimichi Soma. "A mechanical consideration for the shaping of the mandibular path during the occlusal phase of mastication." Journal of Japanese Society of Stomatognathic Function 3, no. 2 (1997): 115–19. http://dx.doi.org/10.7144/sgf.3.115.

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Kane, Jeffrey M., J. Morgan Varner, and Eric E. Knapp. "Novel fuelbed characteristics associated with mechanical mastication treatments in northern California and south-western Oregon, USA." International Journal of Wildland Fire 18, no. 6 (2009): 686. http://dx.doi.org/10.1071/wf08072.

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Mechanically masticated fuelbeds are distinct from natural or logging slash fuelbeds, with different particle size distributions, bulk density, and particle shapes, leading to challenges in predicting fire behavior and effects. Our study quantified some physical properties of fuel particles (e.g. squared quadratic mean diameter, proportion of non-cylindrical particles) and surface fuel loading with planar intercept and plot-based methods in 10 mechanically masticated sites in northern California and south-western Oregon. Total woody fuel load differed among masticated sites, ranging from 15.3 to 63.4 Mg ha–1, with the majority of the load concentrated in the 10-h (53.7%) and 1-h (29.2%) time-lag classes. Masticated fuels were densely packed, with total depths ranging from 4.6 to 8.0 cm and fuelbed bulk densities ranging from 45.9 to 115.3 kg m–3. To accurately quantify loading in masticated fuelbeds, we recommend using a hybrid methodology, where 1-h and 10-h fuel loadings are estimated using a plot-based method and 100-h and 1000-h fuel loadings are estimated using the standard planar intercept method. Most masticated fuelbeds differed in loading by fuel class and fuelbed depth, when compared with existing natural and slash-based fuelbeds, suggesting new fire behavior fuel models specific to masticated fuelbeds may be warranted.

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Danciu, T. E., E. Gagari, R. M. Adam, P. D. Damoulis, and M. R. Freeman. "Mechanical Strain Delivers Anti-apoptotic and Proliferative Signals to Gingival Fibroblasts." Journal of Dental Research 83, no. 8 (August 2004): 596–601. http://dx.doi.org/10.1177/154405910408300803.

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Physical forces play a critical role in the survival and proliferation of many cell types, including fibroblasts. Gingival fibroblasts are exposed to mechanical stress during mastication, orthodontic tooth movement, and wound healing following periodontal surgery. The aim of this study was to examine the effect of mechanical strain on human gingival fibroblasts (hGF). Cells were subjected to short-term (up to 60 min) and long-term (up to 48 hrs) 20% average elongation at 0.1 Hz. We monitored survival signaling by evaluating the phosphorylation status and localization of Forkhead box (FoxO) family members, which are mediators of apoptosis. We also examined strain-induced proliferation by measuring the level of proliferating cell nuclear antigen (PCNA). We observed that cyclic strain caused the phosphorylation and retention in the cytoplasm of FoxO family members. Moreover, mechanical strain resulted in increased ERK kinase phosphorylation and PCNA expression. In conclusion, cyclic strain delivers anti-apoptotic and proliferative stimuli to hGF.

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Barlow, Steven M., and Paul T. Bradford. "Comparison of Perioral Reflex Modulation in the Upper and Lower Lip." Journal of Speech, Language, and Hearing Research 39, no. 1 (February 1996): 55–75. http://dx.doi.org/10.1044/jshr.3901.55.

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The spatiotemporal organization and specificity of the mechanically evoked, short latency penoral response (R1) was sampled from a group of normal adult humans. Perioral reflex activity was sampled during passive and active static force conditions in the presence of servo-controlled mechanical inputs to lip vermilion. Results confirmed that the sensorimotor apparatus of the lower face is very responsive to low level mechanical inputs and highly dependent on several factors including input site (upper vs. lower lip), amount of glabrous tissue stimulated (contactor array size), and task dynamics (passive vs. active subject-generated lip force). Arguments are presented to support the idea that several features of the peripheral sensory environment encoded by primary trigeminal afferents, including afferent gain, specificity, locus, and spatial summation, collectively provide inputs vital to higher order sensory relays in the development of a central representation and dynamic conformational map of perioral space. These sensorimotor features encoded by trigeminal afferents are presumed important for motor learning and maintenance of oromotor control during speech, suck, mastication and swallow, and gesture.

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González, R., I. Montoya, and J. Cárcel. "Review: the Use of Electromyography on Food Texture Assessment." Food Science and Technology International 7, no. 6 (December 2001): 461–71. http://dx.doi.org/10.1106/nrht-l39d-hy1y-8rgb.

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Sensory evaluation (SE) involves evoking, measuring and interpreting human responses to the properties of foods. Among these properties texture is an important one for food acceptability. Texture is mainly perceived through mastication, a process that changes food characteristics throughout time by comminuting and salivation. Electromyography (EMG) has emerged as a new tool in sensory evaluation mainly for assessing texture characteristics. Thus, it is interesting to analyze the knowledge so far generated and the procedures employed. Bipolar surface electrodes are placed on the four main masticatory muscles (masseter right-left and temporalis right-left) and their electric activity recorded during mastication. The signals need to be amplified and filtered, and afterwards their acquisition by a computer allows conditioning and analysis. The output is a series of bursts corresponding to the chews during mastication. EMG parameters include the area under the curve (linked to masticatory work) and voltage (linked to the force exerted) at different moments of the process. Many other parameters are derived from the recording and related to food texture characteristics. EMG allows the study of changes throughout the masticatory process, these changes in EMG parameters permit a better assessment of sensory characteristics than mechanical measurements. Nevertheless, close-fitting correlations have been found between sensorymechanical-EMG measurements. In the literature, texture assessment by using EMG includes many products like carrots, biscuits, cooked meat, cooked rice, cheese, etc., as well as different texture characteristics like tenderness, hardness, crunchiness, juiciness, among others. Nowadays, texture studies involving EMG are mainly linked to describing changes or differences in the signals, good descriptors of perceived differences. Nevertheless for quantifying purposes, in order to allow comparisons among authors, a first step should be undertaken to standardize EMG parameters definition and procedures used in SE.

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Dutta, Abir, Kaushik Mukherjee, Venkata Sundeep Seesala, Kaushik Dutta, Ranjan Rashmi Paul, Santanu Dhara, and Sanjay Gupta. "Load transfer across a mandible during a mastication cycle: The effects of odontogenic tumour." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 234, no. 5 (February 5, 2020): 486–95. http://dx.doi.org/10.1177/0954411920904618.

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The extent to which load transfer in a diseased mandible with odontogenic tumour might influence the potential risk of pathological fracture has scarcely been investigated. The study sought to investigate the quantitative deviations in load transfer across healthy and cancer-affected (diseased) mandibles having odontogenic tumours. The effect of size of the tumours (small: 9 mm diameter, large: 19 mm diameter), and variation in bone mechanical (elastic) properties of the mandible on load transfer in cancer-affected mandibles during a mastication cycle have been investigated. Based on patient-specific computed tomography–scan datasets, detailed three-dimensional finite element models of healthy and diseased mandibles were developed. High stresses of 25–30 MPa and strains ∼700 µε were observed in the healthy mandible during the right molar bite. However, marginal deviations were observed in principal stress distributions in the diseased mandibles with small- and large-sized tumours, as compared to the healthy mandible. Maximum principal strains of ∼1474 µε were found in the body region adjacent to the symphysis region for small-sized tumour. Whereas for large-sized tumour, maximum strains of ∼2700 µε were observed in the right buccal regions. Reduction in Young’s modulus due to different stages of odontogenic tumours had a localised effect on the principal stress distributions, but triggered an abrupt increase in the principal tensile strains. It appears that there is a potential risk of pathological fracture for large-sized odontogenic tumour, owing to high tensile stresses and strains.

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Marek, M. "Interactions Between Dental Amalgams and the Oral Environment." Advances in Dental Research 6, no. 1 (September 1992): 100–109. http://dx.doi.org/10.1177/08959374920060010101.

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Dental amalgam fillings interact in a complex way with the environment in the oral cavity as they are subjected to chemical, biological, mechanical, and thermal forces. These forces change the restoration's appearance and properties, while metal ions, amalgam debris, non-metallic corrosion products, and mercury vapor are released into the oral cavity. The phenomena and conditions that affect the amalgam/ environment interaction include the chemistry and biochemistry of the environment, formation of biofilms on the amalgam surfaces, existence of localized corrosion cells, galvanic contacts with other metallic restorations, abrasion during mastication, and synergistic effects of the different forces. Corrosion processes result in a degradation of the functional amalgam properties, while tarnishing reactions cause discoloration. Corrosion degradation of amalgam fillings is due mainly to localized corrosion cells in pores and crevices. Corrosion on occlusal surfaces is accelerated by abrasion during mastication, which removes the protective surface films. The average total amounts of metal species, including mercury, released per day in vivo from a restoration have not been determined. Much of the reported indirect evidence for high mercury release rates is either unreliable or controversial. A more detailed investigation is needed and will require the development of more sophisticated techniques of sampling in vivo, as well as both experimental and theoretical modeling in vitro.

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Usui, T., K. Maki, Y. Toki, Y. Shibasaki, H. Takanobu, A. Takanishi, D. Hatcher, and A. Miller. "Measurement of mechanical strain on mandibular surface with mastication robot: influence of muscle loading direction and magnitude." Orthodontics & Craniofacial Research 6 (August 2003): 163–67. http://dx.doi.org/10.1034/j.1600-0544.2003.250.x.

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Journal articles on the topic 'Mechanical mastication'

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