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Journal of Oral Rehabilitation Sep 2018Saliva is a complex fluid produced by 3 pairs of major salivary glands and by hundreds of minor salivary glands. It comprises a large variety of constituents and... (Review)
Review
Saliva is a complex fluid produced by 3 pairs of major salivary glands and by hundreds of minor salivary glands. It comprises a large variety of constituents and physicochemical properties, which are important for the maintenance of oral health. Saliva not only protects the teeth and the oropharyngeal mucosa, it also facilitates articulation of speech, and is imperative for mastication and swallowing. Furthermore, saliva plays an important role in maintaining a balanced microbiota. Thus, the multiple functions provided by saliva are essential for proper protection and functioning of the body as a whole and for the general health. A large number of diseases and medications can affect salivary secretion through different mechanisms, leading to salivary gland dysfunction and associated oral problems, including xerostomia, dental caries and fungal infections. The first part of this review article provides an updated insight into our understanding of salivary gland structure, the neural regulation of salivary gland secretion, the mechanisms underlying the formation of saliva, the various functions of saliva and factors that influence salivary secretion under normal physiological conditions. The second part focuses on how various diseases and medical treatment including commonly prescribed medications and cancer therapies can affect salivary gland structure and function. We also provide a brief insight into how to diagnose salivary gland dysfunction.
Topics: Humans; Mastication; Oral Health; Saliva; Salivary Glands; Salivation; Xerostomia
PubMed: 29878444
DOI: 10.1111/joor.12664 -
Clinical Oral Investigations Mar 2022To investigate the effects of dental/skeletal malocclusion and orthodontic treatment on four main objective parameters of chewing and jaw function (maximum occlusal bite... (Review)
Review
OBJECTIVE
To investigate the effects of dental/skeletal malocclusion and orthodontic treatment on four main objective parameters of chewing and jaw function (maximum occlusal bite force [MOBF], masticatory muscle electromyography [EMG], jaw kinematics, and chewing efficiency/performance) in healthy children.
MATERIALS AND METHODS
Systematic searches were conducted in MEDLINE (OVID), Embase, and the Web of Science Core Collection. Studies that examined the four parameters in healthy children with malocclusions were included. The quality of studies and overall evidence were assessed using the Joanna Briggs Institute and GRADE tools, respectively.
RESULTS
The searches identified 8192 studies; 57 were finally included. The quality of included studies was high in nine studies, moderate in twenty-three studies, and low in twenty-five studies. During the primary dentition, children with malocclusions showed similar MOBF and lower chewing efficiency compared to control subjects. During mixed/permanent dentition, children with malocclusion showed lower MOBF and EMG activity and chewing efficiency compared to control subjects. The jaw kinematics of children with unilateral posterior crossbite showed a larger jaw opening angle and a higher frequency of reverse chewing cycles compared to crossbite-free children. There was a low to moderate level of evidence on the effects of orthodontic treatment in restoring normal jaw function.
CONCLUSIONS
Based on the limitations of the studies included, it is not entirely possible to either support or deny the influence of dental/skeletal malocclusion traits on MOBF, EMG, jaw kinematics, and masticatory performance in healthy children. Furthermore, well-designed longitudinal studies may be needed to determine whether orthodontic treatments can improve chewing function in general.
CLINICAL RELEVANCE
Comprehensive orthodontic treatment, which includes evaluation and restoration of function, may or may not mitigate the effects of malocclusion and restore normal chewing function.
Topics: Bite Force; Child; Electromyography; Humans; Malocclusion; Masseter Muscle; Mastication; Masticatory Muscles
PubMed: 34985577
DOI: 10.1007/s00784-021-04356-y -
International Journal of Language &... Jan 2018Clinical swallowing assessment is largely limited to qualitative assessment of behavioural observations. There are limited quantitative data that can be compared with a...
BACKGROUND
Clinical swallowing assessment is largely limited to qualitative assessment of behavioural observations. There are limited quantitative data that can be compared with a healthy population for identification of impairment. The Test of Masticating and Swallowing Solids (TOMASS) was developed as a quantitative assessment of solid bolus ingestion.
AIMS
This research programme investigated test development indices and established normative data for the TOMASS to support translation to clinical dysphagia assessment.
METHODS & PROCEDURES
A total of 228 healthy adults (ages 20-80+ years) stratified by age and sex participated in one or more of four consecutive studies evaluating test-retest and interrater reliability and validity to instrumental assessment. For each study the test required participants to ingest a commercially available cracker with instructions to 'eat this as quickly as is comfortably possible'. Further averaged measures were derived including the number of masticatory cycles and swallows per bite, and time per bite, masticatory cycle and swallow. Initial analyses identified significant differences on salient measures between two commercially available crackers that are nearly identical in shape, size and ingredients, suggesting the need for separate normative samples for specific regional products. Additional analyses on a single cracker identified that the TOMASS was sensitive at detecting changes in performance based on age and sex. Test-retest reliability across days and interrater reliability between clinicians was high, as was validation of observational measures to instrumental correlates of the same behaviours. Therefore, normative data are provided for the TOMASS from a minimum of 80 healthy controls, stratified by age and sex, for each of seven commercially available crackers from broad regions worldwide.
OUTCOMES & RESULTS
Analyses on a single cracker identified Arnott's Salada, and that TOMASS measures were sensitive for detecting changes in performance based on age and sex. Interrater and test-retest reliability across days were high, as was validation of observational measures to instrumental correlates of the same behaviours. Significant differences were identified between two commercially available crackers, nearly identical in shape, size and ingredients, thus normative samples for specific regional products were required. Normative data were then acquired for the TOMASS from a minimum of 80 healthy controls, stratified by age and sex, for each of seven commercially available crackers from broad regions worldwide.
CONCLUSIONS & IMPLICATIONS
The TOMASS is presented as a valid, reliable and broadly normed clinical assessment of solid bolus ingestion. Clinical application may help identify dysphagic patients at bedside and provide a non-invasive, but sensitive, measure of functional change in swallowing.
Topics: Adult; Aged; Aged, 80 and over; Deglutition; Deglutition Disorders; Diagnostic Techniques, Digestive System; Female; Humans; Male; Mastication; Middle Aged; Reproducibility of Results; Young Adult
PubMed: 28677236
DOI: 10.1111/1460-6984.12332 -
Current Opinion in Neurobiology Dec 2023Feeding behavior involves a complex organization of neural circuitry and interconnected pathways between the cortex, the brainstem, and muscles. Elevated synchronicity... (Review)
Review
Feeding behavior involves a complex organization of neural circuitry and interconnected pathways between the cortex, the brainstem, and muscles. Elevated synchronicity is required starting from the moment the animal brings the food to its mouth, chews, and initiates subsequent swallowing. Moreover, orofacial sensory and motor systems are coordinated in a way to optimize movement patterns as a result of integrating information from premotor neurons. Recent studies have uncovered significant discoveries employing various and creative techniques in order to identify key components in these vital functions. Here, we attempt to provide a brief overview of our current knowledge on orofacial systems. While our focus will be on recent breakthroughs regarding the masticatory machinery, we will also explore how it is sometimes intertwined with other functions, such as swallowing and limb movement.
Topics: Animals; Mastication; Neurons; Feeding Behavior; Movement; Brain Stem
PubMed: 37913688
DOI: 10.1016/j.conb.2023.102805 -
MMW Fortschritte Der Medizin May 2024
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The Veterinary Clinics of North... Dec 2020Odontoplasty (floating and occlusal equilibration) is the most commonly performed procedure in equine dentistry. From an anatomic perspective, an irregular occlusal... (Review)
Review
Odontoplasty (floating and occlusal equilibration) is the most commonly performed procedure in equine dentistry. From an anatomic perspective, an irregular occlusal surface, prominent cingula, transverse ridges, and enamel points all contribute to the function, form, and longevity of the equine cheek tooth. With limited reserve crown available and an average functional life range between 18 and 25 years, removal of tooth structure should be conservative. The authors consider a quality oral examination to be the most important dental procedure performed in the horse. Individual tooth evaluation should lead to a specific diagnosis and treatment plan. Tooth odontoplasty should be site-specific.
Topics: Animals; Horse Diseases; Horses; Malocclusion; Mastication
PubMed: 33067101
DOI: 10.1016/j.cveq.2020.08.011 -
L' Orthodontie Francaise Mar 2022Orthodontic diagnosis is generally centered on the morphological aspect, as is the treatment: it is most often a matter of modifying the shape of the arches and their...
INTRODUCTION
Orthodontic diagnosis is generally centered on the morphological aspect, as is the treatment: it is most often a matter of modifying the shape of the arches and their relationships to adjust them to a morphological norm with the goal of a beautiful smile. However legitimate it may be, this diagnostic approach may seem reductive if we consider that teeth are also used to chew: it is even their main function. But how to take into account the masticatory function?
MATERIALS AND METHODS
With the help of clinical examples, the author develops the modalities of the clinical exploration of the mandibular kinematics, reflection of the mastication, on which the systemic diagnosis is based. It highlights the proprioceptive resources of the masticatory system that systemic treatment targets during the correction of malocclusions.
CONCLUSION
The systemic diagnosis highlights the functional role of the arches, inviting, during their correction, to rehabilitate mastication in order to improve their stability.
Topics: Humans; Malocclusion; Mandible; Mastication
PubMed: 35785945
DOI: 10.1684/orthodfr.2022.77 -
BioMed Research International 2015Exposure to chronic stress induces various physical and mental effects that may ultimately lead to disease. Stress-related disease has become a global health problem.... (Review)
Review
Exposure to chronic stress induces various physical and mental effects that may ultimately lead to disease. Stress-related disease has become a global health problem. Mastication (chewing) is an effective behavior for coping with stress, likely due to the alterations chewing causes in the activity of the hypothalamic-pituitary-adrenal axis and autonomic nervous system. Mastication under stressful conditions attenuates stress-induced increases in plasma corticosterone and catecholamines, as well as the expression of stress-related substances, such as neurotrophic factors and nitric oxide. Further, chewing reduces stress-induced changes in central nervous system morphology, especially in the hippocampus and hypothalamus. In rodents, chewing or biting on wooden sticks during exposure to various stressors reduces stress-induced gastric ulcer formation and attenuates spatial cognitive dysfunction, anxiety-like behavior, and bone loss. In humans, some studies demonstrate that chewing gum during exposure to stress decreases plasma and salivary cortisol levels and reduces mental stress, although other studies report no such effect. Here, we discuss the neuronal mechanisms that underline the interactions between masticatory function and stress-coping behaviors in animals and humans.
Topics: Adaptation, Psychological; Animals; Anxiety; Catecholamines; Cognition Disorders; Hippocampus; Humans; Mastication; Stress, Psychological
PubMed: 26090453
DOI: 10.1155/2015/876409 -
Journal of Oral Rehabilitation Apr 2017The paper reviews human mastication, focusing on its age-related changes. The first part describes mastication adaptation in young healthy individuals. Adaptation to... (Review)
Review
The paper reviews human mastication, focusing on its age-related changes. The first part describes mastication adaptation in young healthy individuals. Adaptation to obtain a food bolus ready to be swallowed relies on variations in number of cycles, muscle strength and volume of emitted saliva. As a result, the food bolus displays granulometric and rheological properties, the values of which are maintained within the adaptive range of deglutition. The second part concerns healthy ageing. Some mastication parameters are slightly modified by age, but ageing itself does not impair mastication, as the adaptation possibilities remain operant. The third part reports on very aged subjects, who display frequent systemic or local diseases. Local and/or general diseases such as tooth loss, salivary defect, or motor impairment are then indistinguishably superimposed on the effects of very old age. The resulting impaired function increases the risk of aspiration and choking. Lastly, the consequences for eating behaviour and nutrition are evoked.
Topics: Aging; Bite Force; Deglutition; Eating; Food; Humans; Mastication; Salivation; Tooth Loss
PubMed: 28029687
DOI: 10.1111/joor.12478 -
International Journal of Medical... 2015Mastication (chewing) is important not only for food intake, but also for preserving and promoting the general health. Recent studies have showed that mastication helps... (Review)
Review
Mastication (chewing) is important not only for food intake, but also for preserving and promoting the general health. Recent studies have showed that mastication helps to maintain cognitive functions in the hippocampus, a central nervous system region vital for spatial memory and learning. The purpose of this paper is to review the recent progress of the association between mastication and the hippocampus-dependent cognitive function. There are multiple neural circuits connecting the masticatory organs and the hippocampus. Both animal and human studies indicated that cognitive functioning is influenced by mastication. Masticatory dysfunction is associated with the hippocampal morphological impairments and the hippocampus-dependent spatial memory deficits, especially in elderly. Mastication is an effective behavior for maintaining the hippocampus-dependent cognitive performance, which deteriorates with aging. Therefore, chewing may represent a useful approach in preserving and promoting the hippocampus-dependent cognitive function in older people. We also discussed several possible mechanisms involved in the interaction between mastication and the hippocampal neurogenesis and the future directions for this unique fascinating research.
Topics: Cognition; Hippocampus; Humans; Learning; Mastication; Memory; Neurogenesis
PubMed: 26078711
DOI: 10.7150/ijms.11911