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Pain Research & Management 2020Experimental and model tests were conducted on ten fresh porcine temporomandibular joint discs. The average thickness of disc tissue was, accordingly, 2.77 mm for the... (Review)
Review
MATERIAL
Experimental and model tests were conducted on ten fresh porcine temporomandibular joint discs. The average thickness of disc tissue was, accordingly, 2.77 mm for the anterior zone, 3.98 mm for the posterior, and 1.54 mm for the intermediate. The selection of research material in the form of porcine discs was due to the similarity to human discs.
METHODS
Discs were loaded in cycles, a temporary course with the amplitude 3 N and frequency 0.07 Hz, and growth in the load was 1 N/s. The selection of load frequency was due to real conditions of temporomandibular joint functioning during mastication. The necessary experimental research was conducted on a testing machine with a measurement range of 2.5 kN.
RESULTS
The obtained numeric calculation results indicate that the number of load cycles has a decisive impact on the limitation of energy dispersion capacity through disc tissue. This phenomenon was observed in all the studies on the disc areas. Along with the growth in load cycles, discs are stiffened, and the most significant stiffness was observed in the intermediate area.
CONCLUSIONS
Based on the conducted research, it should be concluded that excessive load affecting temporomandibular joints caused by the act of mastication and occlusal forces generated during parafunction and in people with defined long-term bruxism has crucial importance on biomechanical disc properties and hence the course of temporomandibular joint conditions.
Topics: Animals; Biomechanical Phenomena; Bruxism; Mastication; Swine; Temporomandibular Joint Disc; Temporomandibular Joint Disorders
PubMed: 33082893
DOI: 10.1155/2020/6032832 -
Current Pharmaceutical Design 2016Mastication and swallowing are the first stage of digestion involving several motor processes such as food intake, intra-oral food transport, bolus formation and chewing... (Review)
Review
Mastication and swallowing are the first stage of digestion involving several motor processes such as food intake, intra-oral food transport, bolus formation and chewing and swallowing reflex. These complicated motor functions are accomplished by the well-coordinated activities in the jaw, hyoid, tongue, facial and pharyngeal muscles. Although the basic activity patterns of these movements are controlled by the brainstem pattern generators, these movements generate various peripheral sensory inputs. Among the sensory inputs, it is well-known that somatic sensory inputs play important roles in reflexively modulating the movements so that the final motor outputs fit the environmental demand. However, little is known about the effects of chemical sensory inputs such as taste and olfaction originating from the ingested foods by these movements. A possible reason could be raised that cognition of the chemical sensory inputs at the higher brain also influences the movements, so it is difficult to discuss the neural mechanisms underlying the observed effect. In this review, we focus on the effects of chemical sensory inputs on the masticatory movements and initiation of swallowing. We first summarize chemical sensory inputs occurring during mastication and swallowing, and their receptive mechanisms. In addition, we will introduce the effect of application of monosodium L-glutamate (MSG) solution as an umami taste to the oropharynx on the swallow initiation which is involuntary controlled and the possible neural mechanisms underlying this effect is discussed.
Topics: Animals; Deglutition; Humans; Mastication; Sodium Glutamate
PubMed: 26881439
DOI: 10.2174/1381612822666160216151150 -
BioMed Research International 2015
Topics: Humans; Mastication; Stress, Psychological
PubMed: 26078950
DOI: 10.1155/2015/412493 -
Journal of Oral Rehabilitation Mar 2016The dental occlusion is an important aspect of clinical dentistry; there are diverse functional demands ranging from highly precise tooth contacts to large crushing... (Review)
Review
The dental occlusion is an important aspect of clinical dentistry; there are diverse functional demands ranging from highly precise tooth contacts to large crushing forces. Further, there are dogmatic, passionate and often diverging views on the relationship between the dental occlusion and various diseases and disorders including temporomandibular disorders, non-carious cervical lesions and tooth movement. This study provides an overview of the biomechanics of the masticatory system in the context of the dental occlusion's role in function. It explores the adaptation and precision of dental occlusion, its role in bite force, jaw movement, masticatory performance and its influence on the oro-facial musculoskeletal system. Biomechanics helps us better understand the structure and function of biological systems and consequently an understanding of the forces on, and displacements of, the dental occlusion. Biomechanics provides insight into the relationships between the dentition, jaws, temporomandibular joints, and muscles. Direct measurements of tooth contacts and forces are difficult, and biomechanical models have been developed to better understand the relationship between the occlusion and function. Importantly, biomechanical research will provide knowledge to help correct clinical misperceptions and inform better patient care. The masticatory system demonstrates a remarkable ability to adapt to a changing biomechanical environment and changes to the dental occlusion or other components of the musculoskeletal system tend to be well tolerated.
Topics: Biomechanical Phenomena; Bite Force; Humans; Jaw; Malocclusion; Mastication; Masticatory Muscles; Movement
PubMed: 26371622
DOI: 10.1111/joor.12345 -
Monographs in Oral Science 2020An individual's oral health status has a profound impact on his/her acquisition and utilization of nutrients and interchangeably the nutrients an individual consumes... (Review)
Review
An individual's oral health status has a profound impact on his/her acquisition and utilization of nutrients and interchangeably the nutrients an individual consumes determine the state of oral health by preventing tooth loss and oral diseases. Oral diseases have a considerable impact on the masticatory function which is a critical first step in oral processing of food materials for nutrient procurement. Specifically, a section of this chapter is dedicated to the physiology of masticatory function and to the recent acknowledgement of its influence on memory and cognition, both during development and aging. A description of the occlusal and skeletal pathologies that affect the balance of the chewing pattern and related muscular activation is provided. Intact neurocognitive functions and dentition are essential in mastication to achieve coordinated movements of the teeth and tongue to help propel the food material for ingestion and subsequent nutrient absorption. The tongue is equipped with chemoreceptive, gustatory cells, which modulate taste perception and contain metabolic hormones mediating satiety. Concomitantly, salivary processes, which are stimulated with the anticipation of food ingestion and those which occur during mastication of the food material, initiate digestive enzymes in the mouth and stomach and are important in affecting appetite and food bioavailability. Therefore, oral structures such as the dentition, tongue, and saliva in the context of mastication and nutrient acquisition will be reviewed as well as their impact on food choice and subsequent nutritional status.
Topics: Diet; Female; Male; Mastication; Oral Health; Taste Perception
PubMed: 31940641
DOI: 10.1159/000455383 -
Journal of Oral Rehabilitation Jun 2021A large number of methodological procedures and experimental conditions are reported to describe the masticatory process. However, similar terms are sometimes employed... (Review)
Review
A large number of methodological procedures and experimental conditions are reported to describe the masticatory process. However, similar terms are sometimes employed to describe different methodologies. Standardisation of terms is essential to allow comparisons among different studies. This article was aimed to provide a consensus concerning the terms, definitions and technical methods generally reported when evaluating masticatory function objectively and subjectively. The consensus is based on the results from discussions and consultations among world-leading researchers in the related research areas. Advantages, limitations and relevance of each method are also discussed. The present consensus provides a revised framework of standardised terms to improve the consistent use of masticatory terminology and facilitate further investigations on masticatory function analysis. In addition, this article also outlines various methods used to evaluate the masticatory process and their advantages and disadvantages in order to help researchers to design their experiments.
Topics: Consensus; Humans; Mastication
PubMed: 33638156
DOI: 10.1111/joor.13161 -
The Angle Orthodontist Mar 2022To investigate the masticatory (masticatory performance, bite force, swallowing threshold, muscle activity, and questionnaires) and nutritional (nutrient intake) impacts... (Review)
Review
OBJECTIVES
To investigate the masticatory (masticatory performance, bite force, swallowing threshold, muscle activity, and questionnaires) and nutritional (nutrient intake) impacts of the activation and/or installation of different orthodontic appliances (fixed labial, lingual appliances, and clear aligners).
MATERIALS AND METHODS
Six electronic databases and gray literature were searched (up to May 2021) for relevant studies evaluating mastication and nutrition after activation/installation of orthodontic appliances. This review followed PRISMA guidelines and was registered at PROSPERO (CRD42020199510). The risk of bias (RoB 2 and ROBINS-I) and evidence quality Grading of Recommendations Assessment, Development, and Evaluation were analyzed.
RESULTS
Of 4226 recorded and screened, 15 studies were finally included. Masticatory performance (standardized mean difference [SMD]: 1.069; 95% coefficient interval [CI]: 0.619 to 1.518) and bite force (SMD: -2.542; 95% CI: -4.867 to -0.217) reduced in the first 24 to 48 hours of fixed labial appliance installation/activation, but they were both normalized after 30 days (P > .05). The swallowing threshold remained constant (P > .05). Nutritional intake was rarely reported but showed copper (P = .002) and manganese (P = .016) reductions, with higher calorie and fat intake (P < .05). Lingual appliances impacted chewing more than labial, and clear aligner wearers reported fewer chewing problems (P < .001). Low to very low levels of evidence were found.
CONCLUSIONS
Based on low to very low levels of evidence, mastication was reduced during the first 24 to 48 hours of fixed labial appliance activation/installation, but it was transitory (up to 30 days). Due to insufficient data, the nutritional impact of orthodontic appliances was not conclusive.
Topics: Bite Force; Mastication; Orthodontic Appliances; Orthodontic Appliances, Fixed; Tongue
PubMed: 34878525
DOI: 10.2319/061221-469.1 -
Archives of Gerontology and Geriatrics 2017A substantial number of elderly people suffer from cognitive impairment and dementia, which are considered to have various risk factors, including masticatory... (Review)
Review
PURPOSE
A substantial number of elderly people suffer from cognitive impairment and dementia, which are considered to have various risk factors, including masticatory dysfunction; however, the association between mastication and cognition is inconclusive. The objectives of this systematic review were to provide an overview of the literature on (1) the association between mastication and cognitive function and (2) the association between mastication and dementia incidence, in elderly people.
MATERIALS AND METHODS
Searches were conducted on five electronic databases (PubMed, EMBASE, CINHL, Cochrane Library, and Pro Quest) and publications were selected that met the following criteria: published between 2005 and 2015, written in English, and assessed associations between mastication and cognitive function, cognitive decline and dementia among population over 40 years old. The included publications were analyzed for study design, main conclusions, and strength of evidence by two reviewers who screened all abstracts and full-text articles, abstracted data and performed quality assessments by using a critical appraisal tool.
RESULTS
A total of 33 articles (22 cross-sectional, and 11 prospective cohort studies) were evaluated. Poorer mastication was associated with lower cognitive function in 15 of the 17 cross-sectional studies and steeper decline in 5 of the 6 prospective studies. Poorer mastication was one of significant risk factors for having dementia or mild memory impairment (MMI) in 4 of 5 cross-sectional studies and for the incidence of dementia or MMI in 4 of 5 prospective studies.
CONCLUSIONS
Most studies point to a positive association between mastication and cognitive function, including dementia among elderly people.
Topics: Aged; Cognition Disorders; Dementia; Humans; Mastication; Risk Factors
PubMed: 28042986
DOI: 10.1016/j.archger.2016.12.006 -
Gerodontology Mar 2019This article explores the multifactorial relationship between mastication and cognition, with a focus on dementia. Older persons, especially those with dementia, are at... (Review)
Review
This article explores the multifactorial relationship between mastication and cognition, with a focus on dementia. Older persons, especially those with dementia, are at great risk of suffering from oral health problems such as orofacial pain and loss of natural teeth. A possible explanation could be that the cognitive and motor impairments resulting from dementia cause a decrease in self-care and as such, a worsening of oral health. An alternative explanation is that cognition and oral health influence each other. Animal studies show that a decrease in masticatory activity, for example, due to a soft diet or loss of teeth, causes memory loss and neuronal degeneration. The relationship between mastication and cognition has also been researched in human studies, but a cause-effect relationship has not been proven. It is likely that multiple factors play a role in this relationship, such as self-care, nutrition, stress and pain.
Topics: Aged; Animals; Brain; Cognition; Dementia; Humans; Mastication; Mice; Middle Aged; Models, Animal
PubMed: 30480331
DOI: 10.1111/ger.12380 -
CoDAS 2014To present recent studies that used the ultrasound in the fields of Speech Language Pathology and Audiology, which evidence possibilities of the applicability of this... (Review)
Review
PURPOSE
To present recent studies that used the ultrasound in the fields of Speech Language Pathology and Audiology, which evidence possibilities of the applicability of this technique in different subareas.
RESEARCH STRATEGY
A bibliographic research was carried out in the PubMed database, using the keywords "ultrasonic," "speech," "phonetics," "Speech, Language and Hearing Sciences," "voice," "deglutition," and "myofunctional therapy," comprising some areas of Speech Language Pathology and Audiology Sciences. The keywords "ultrasound," "ultrasonography," "swallow," "orofacial myofunctional therapy," and "orofacial myology" were also used in the search.
SELECTION CRITERIA
Studies in humans from the past 5 years were selected. In the preselection, duplicated studies, articles not fully available, and those that did not present direct relation between ultrasound and Speech Language Pathology and Audiology Sciences were discarded.
DATA ANALYSIS
The data were analyzed descriptively and classified subareas of Speech Language Pathology and Audiology Sciences. The following items were considered: purposes, participants, procedures, and results.
RESULTS
We selected 12 articles for ultrasound versus speech/phonetics subarea, 5 for ultrasound versus voice, 1 for ultrasound versus muscles of mastication, and 10 for ultrasound versus swallow. Studies relating "ultrasound" and "Speech Language Pathology and Audiology Sciences" in the past 5 years were not found.
CONCLUSION
Different studies on the use of ultrasound in Speech Language Pathology and Audiology Sciences were found. Each of them, according to its purpose, confirms new possibilities of the use of this instrument in the several subareas, aiming at a more accurate diagnosis and new evaluative and therapeutic possibilities.
Topics: Deglutition; Humans; Mastication; Speech-Language Pathology; Ultrasonography; Voice
PubMed: 25590916
DOI: 10.1590/2317-1782/20142013086