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Journal of Integrative Plant Biology Feb 2022Success of plants largely depends on their ability to defend against herbivores. Since emergence of the first voracious consumers, plants maintained adapting their... (Review)
Review
Success of plants largely depends on their ability to defend against herbivores. Since emergence of the first voracious consumers, plants maintained adapting their structures and chemistry to escape from extinction. The constant pressure was further accelerated by adaptation of herbivores to plant defenses, which all together sparked the rise of a chemical empire comprised of thousands of specialized metabolites currently found in plants. Metabolic diversity in the plant kingdom is truly amazing, and although many plant metabolites have already been identified, a large number of potentially useful chemicals remain unexplored in plant bio-resources. Similarly, biosynthetic routes for plant metabolites involve many enzymes, some of which still wait for identification and biochemical characterization. Moreover, regulatory mechanisms that control gene expression and enzyme activities in specialized metabolism of plants are scarcely known. Finally, understanding of how plant defense chemicals exert their toxicity and/or repellency against herbivores remains limited to typical examples, such as proteinase inhibitors, cyanogenic compounds and nicotine. In this review, we attempt summarizing the current status quo in metabolic defense of plants that is predominantly based on the survey of ubiquitous examples of plant interactions with chewing herbivores.
Topics: Adaptation, Physiological; Herbivory; Mastication; Plants
PubMed: 34914192
DOI: 10.1111/jipb.13204 -
Journal of Dental Research Feb 2021The periodontal ligament (PDL) plays a critical role in providing immediate response to abrupt high loads during mastication while also facilitating slow remodeling of...
The periodontal ligament (PDL) plays a critical role in providing immediate response to abrupt high loads during mastication while also facilitating slow remodeling of the alveolar bone. The PDL exceptional functionality is permitted by the unique nonuniform structure of the tissue. Two distinct areas that are critical to PDL function were previously identified: the furcation and the dense collar. Despite their hypothesized functions in tooth movement and maintenance, these 2 regions have not yet been compared within the context of their native environment. Therefore, the objective of this study is to elucidate the extracellular matrix (ECM) structure, composition, and biomechanical function of the furcation and the collar regions while maintaining the 3-dimensional (3D) structure in the murine PDL. We identify significant difference between the collar and furcation regions in both structure and mechanical properties. Specifically, we observed unique longitudinal structures in the dense collar that correlate with type VI collagen and LOX, both of which are associated with increased type I collagen density and tissue stiffness and are therefore proposed to function as scaffolds for tooth stabilization. We also found that the collar region is stiffer than the furcation region and therefore suggest that the dense collar acts as a suspense structure of the tooth within the bone during physiological loading. The furcation region of the PDL contained more proteins associated with reduced stiffness and higher tissue remodeling, as well as a dual mechanical behavior, suggesting a critical function in loads transfer and remodeling of the alveolar bone. In summary, this work unravels the nonuniform nature of the PDL within the 3D structural context and establishes understanding of regional PDL function, which opens new avenues for future studies of remodeling, regeneration, and disease.
Topics: Animals; Collagen Type I; Mastication; Mice; Periodontal Ligament; Tooth; Tooth Movement Techniques
PubMed: 33043806
DOI: 10.1177/0022034520962455 -
European Journal of Cancer Care Nov 2022Treatment for oral cancer can impair oral functions such as mastication, which may negatively affect quality of life (QoL). In this review, an overview is provided of... (Review)
Review
INTRODUCTION
Treatment for oral cancer can impair oral functions such as mastication, which may negatively affect quality of life (QoL). In this review, an overview is provided of masticatory ability in patients treated for oral cancer.
METHODS
The PubMed (MEDLINE), Embase and Cochrane databases were systematically searched for scientific literature on masticatory ability in relation to QoL in patients treated for oral cancer. Studies were included when oral cancer treatment was provided, and the University of Washington Quality of Life (UW-QoL) questionnaire was used. Risk of bias (MINORS) was independently assessed by two authors.
RESULTS
The PubMed (MEDLINE), Embase and Cochrane search yielded 575 unique records of which 111 were assessed full text, and 27 studies were included. The UW-QoL mastication scores ranged from 31.9 to 97.4. There was a wide variety in methodology, patient groups, tumour site, treatment and assessment moment, to such a degree that outcome scores are difficult to compare.
CONCLUSION
The wide variety in studies exploring health-related QoL in relation to mastication in oral cancer patients prevents the identification of possible relations between treatment, masticatory ability and QoL. Our findings underline the limitations in currently available literature and indicate the necessity for more comparable research.
Topics: Humans; Quality of Life; Mastication; Mouth Neoplasms; Surveys and Questionnaires
PubMed: 36239005
DOI: 10.1111/ecc.13744 -
International Journal For Numerical... Jul 2023Long-term excessive forces loading from muscles of mastication during mandibular motions may result in disorders of temporomandibular joint (TMJ), myofascial pain, and...
Long-term excessive forces loading from muscles of mastication during mandibular motions may result in disorders of temporomandibular joint (TMJ), myofascial pain, and restriction of jaw opening and closing. Current analysis of mandibular movements is generally conducted with a single opening, protrusive and lateral movements rather than composite motions that the three can be combined arbitrarily. The objective of this study was to construct theoretical equations reflecting the correlation between composite motions and muscle forces, and consequently to analyze the mandibular composite motions and the tensions of muscles of mastication in multiple dimensions. The muscle performances such as strength, power, and endurance of mandibular motions were analyzed and the effective motion range of each muscle was derived. The mandibular composite motion model was simplified by calculating muscle forces. An orthogonal rotation matrix based on muscle forces was established. A 3D printed mandible was used for in vitro simulation of mandibular motions on a robot and measurements of force were conducted. The theoretical model and forces were verified through a trajectory tracing experiment of mandibular motions driven by a 6-axis robot with force/torque sensors. Through the analysis of the mandibular composite motion model, the motion form was obtained and transferred to guide the motions of the robot. The error between the experimental data obtained by the 6-axis force/torque sensors and the theoretical data was within 0.6 N. Our system provides excellent visualization for analyzing the changes of muscle forces and locations during various mandibular movements. It is useful for clinicians to diagnose and formulate treatment for patients who suffer from (temporomandibular joint disorders) TMDs and restrict jaw movements. The system can potentially offer the comparison before and after treatment of TMDs or jaw surgery.
Topics: Humans; Mandible; Temporomandibular Joint; Temporomandibular Joint Disorders; Movement; Mastication; Range of Motion, Articular
PubMed: 37096732
DOI: 10.1002/cnm.3716 -
Journal of Oral Rehabilitation Oct 2023With the ageing process changes in the musculature of oro-facial structures take place, consequently there is a reduction in the strength and mobility of the lips,... (Observational Study)
Observational Study
BACKGROUND
With the ageing process changes in the musculature of oro-facial structures take place, consequently there is a reduction in the strength and mobility of the lips, tongue and cheeks.
OBJECTIVE
The aim of this study was to correlate oro-facial structures and chewing and swallowing functions among a group of senior citizens and young adults and check the influence of lip and tongue pressure of these functions.
METHODS
This is an observational, cross-sectional and analytical study. Thirty seniors with an average age of 67.13 years and 30 young adults with an average age of 22.03 years participated in the study. The Oro-facial Myofunctional Assessment Protocol with Scores for the Elderly and the Oro-facial Myofunctional Assessment Protocol with Expanded Scores were also used. The evaluation of the force of pressure of the lips and tip and dorsum of the tongue was carried out using the Biofeedback device Pró-Fono: Lip and Tongue Pressure.
RESULTS
Young adults had a higher evaluation score for the aspect/posture of the face, cheeks, lips, mentalis muscle, tongue, mobility of lips, tongue, jaw and cheeks, chewing and swallowing functions, total time and chewing strokes, and tip pressure and dorsum of tongue. According to the Structural Equation Modelling, a direct relationship was found between the tongue dorsum pressure force and the swallowing function.
CONCLUSION
With healthy ageing changes occurring in the appearance, posture and mobility of the lips, tongue, jaw and cheeks, with the seniors and reduced performance of chewing and swallowing functions.
Topics: Young Adult; Humans; Aged; Adult; Tongue; Lip; Cross-Sectional Studies; Pressure; Deglutition; Mastication
PubMed: 37282365
DOI: 10.1111/joor.13531 -
The Journal of Experimental Biology Apr 2021Mastication and drinking are rhythmic and cyclic oral behaviors that require interactions between the tongue, jaw and a food or liquid bolus, respectively. During...
Mastication and drinking are rhythmic and cyclic oral behaviors that require interactions between the tongue, jaw and a food or liquid bolus, respectively. During mastication, the tongue transports and positions the bolus for breakdown between the teeth. During drinking, the tongue aids in ingestion and then transports the bolus to the oropharynx. The objective of this study was to compare jaw and tongue kinematics during chewing and drinking in pigs. We hypothesized there would be differences in jaw gape cycle dynamics and tongue protraction-retraction between behaviors. Mastication cycles had an extended slow-close phase, reflecting tooth-food-tooth contact, whereas drinking cycles had an extended slow-open phase, corresponding to tongue protrusion into the liquid. Compared with chewing, drinking jaw movements were of lower magnitude for all degrees of freedom examined (jaw protraction, yaw and pitch), and were bilaterally symmetrical with virtually no yaw. The magnitude of tongue protraction-retraction (Txt), relative to a mandibular coordinate system, was greater during mastication than during drinking, but there were minimal differences in the timing of maximum and minimum Txt relative to the jaw gape cycle between behaviors. However, during drinking, the tongue tip is often located outside the oral cavity for the entire cycle, leading to differences between behaviors in the timing of anterior marker maximum Txt. This demonstrates that there is variation in tongue-jaw coordination between behaviors. These results show that jaw and tongue movements vary significantly between mastication and drinking, which hints at differences in the central control of these behaviors.
Topics: Animals; Biomechanical Phenomena; Drinking; Jaw; Mastication; Movement; Swine; Tongue
PubMed: 33674496
DOI: 10.1242/jeb.239509 -
Journal of Oral Rehabilitation Dec 2023Adequate muscle activity is important for the success of oral rehabilitation: it maintains the integrity of the stomatognathic system and is responsible for chewing... (Review)
Review
BACKGROUND
Adequate muscle activity is important for the success of oral rehabilitation: it maintains the integrity of the stomatognathic system and is responsible for chewing movements needed to break, crush and grind food.
OBJECTIVE
To compare muscle activity using electromyography (EMG) while clenching or chewing soft and/or hard foods among individuals with natural dentition (ND) and edentulous patients rehabilitated with dental prostheses.
METHODS
This review was conducted until March, 2023, and the research question was "Is the muscle activity of edentulous patients rehabilitated with dental prostheses similar to that of dentate individuals?" A search strategy was conducted in PubMed/MEDLINE, The Cochrane Library, Web of Science, Lilacs, Embase and manual journal searches.
RESULTS
Ten studies were included in the analysis. Most of them reported that individuals with ND had significant higher muscle activity (clenching or chewing) than complete dentures (CD) users. However, no difference was observed between patients with full mouth implant-supported fixed dental prosthesis (ISFDP) and ND. Additionally, two studies compared patients with mandibular ISFDP with maxillary CD and individuals with ND and found no differences; however, one study concluded that patients with ISFDP with CD (maxillary or mandibular) had lower muscle activity than individuals with ND. Only one study reported a higher muscle activity in patients with full-mouth ISFDP than in individuals with ND.
CONCLUSIONS
Bimaxillary CD users had lower muscle activity than individuals with ND. During rehabilitation, the muscle activity of patients with full-mouth ISFDP and mandibular ISFDP with maxillary CD is similar to individuals with ND.
Topics: Humans; Dental Prosthesis, Implant-Supported; Mouth, Edentulous; Denture, Complete; Mastication; Muscles; Dental Implants; Denture, Overlay
PubMed: 37605296
DOI: 10.1111/joor.13564 -
Zhejiang Da Xue Xue Bao. Yi Xue Ban =... Jun 2023Chewing-side preference is one of the risk factors for temporomandibular disorders (TMD), and people with chewing-side preference is more prone to have short and... (Review)
Review
Chewing-side preference is one of the risk factors for temporomandibular disorders (TMD), and people with chewing-side preference is more prone to have short and displaced condyles, increased articular eminence inclination and glenoid fossa depth. The proportion of TMD patients with chewing-side preference is often higher than that of the normal subjects. Clinical studies have shown a strong correlation between chewing-side preference and TMD symptoms and signs; and animal studies have shown that chewing-side preference can affect the growth, development, damage and repair of the mandible. After long-term unilateral mastication, changes in the stress within the joint cause the imbalance of temporomandibular joint (TMJ) structural reconstruction, the transformation and even destruction of the fiber structure of masticatory muscle, resulting in uncoordinated movement of bilateral muscles. The joint neurogenic diseases caused by the increase of neuropeptide substance P and calcitonin-gene-related-peptide (CGRP) released locally by TMJ may be the mechanism of TMD. This article reviews the research progress of the influence of chewing-side preference on the structure of TMJ, the relationship between chewing-side preference and TMD, and the related mechanisms.
Topics: Humans; Mastication; Temporomandibular Joint; Temporomandibular Joint Disorders; Mandible
PubMed: 37476950
DOI: 10.3724/zdxbyxb-2023-0066 -
Journal of Dentistry Feb 2023To give an overview of the evidence on the associations between oral condition factors and masticatory performance of adults, and to evaluate the direction and level of... (Meta-Analysis)
Meta-Analysis Review
OBJECTIVES
To give an overview of the evidence on the associations between oral condition factors and masticatory performance of adults, and to evaluate the direction and level of the associations.
DATA/SOURCES
Medline (PubMed), Embase (Ovid) and CINAHL Plus (EBSCOhost) were searched up to May 2022 for cross-sectional studies on oral conditions and masticatory performance in adults. Methodological quality of the included studies was independently evaluated based on the Joanna Briggs Institute critical appraisal checklist for analytical cross-sectional studies. Data on the associations between oral condition factors and masticatory performance were extracted. Meta-analysis was conducted on correlation coefficients.
STUDY SELECTION
Of the 8,035 records identified, 97 articles (88 studies) were included in the qualitative synthesis, and 18 studies were included in the meta-analyses. Among the oral condition factors that had associations with masticatory performance, the number of natural/remaining teeth or functional tooth pairs was reported by the largest number of studies, followed by perioral muscle status, dental prosthetic status, oral moisture status and periodontal status. Results of the meta-analyses showed that the positive association with the number of natural/remaining teeth was the strongest (pooled correlation coefficient: 0.51, 95%CI: 0.48 to 0.54), followed by the number of functional tooth pairs, maximum tongue force/pressure, while the association with the oral moisture status was the weakest.
CONCLUSIONS
Number of natural/remaining teeth and functional tooth pairs, perioral muscle status, oral moisture status, dental prosthetic status and periodontal status are the main oral condition factors influencing masticatory performance. Based on the limited evidence available, among these factors, the number of natural/remaining teeth has the strongest positive association, with a very low quality of evidence.
CLINICAL SIGNIFICANCE
This study provides valuable information on the oral condition factors associated with masticatory performance, which would be important for policymakers and clinical practitioners when deciding on the strategies for improving the masticatory performance of adults. This review highlights the need for standardization of measures and classifications of masticatory performance and oral conditions.
REGISTRATION
PROSPERO (registration number: CRD42021256824).
Topics: Humans; Adult; Bite Force; Mastication; Cross-Sectional Studies; Mouth, Edentulous
PubMed: 36563840
DOI: 10.1016/j.jdent.2022.104395 -
In Vitro Mastication Simulation and Wear Test of Virgilite and Advanced Lithium Disilicate Ceramics.The International Journal of... 2022To compare wear behavior, durability during in vitro mastication simulation, and fracture force of an established and a novel lithium disilicate CAD/CAM material, as...
PURPOSE
To compare wear behavior, durability during in vitro mastication simulation, and fracture force of an established and a novel lithium disilicate CAD/CAM material, as well as to examine the impact of cementation and reduced ceramic thickness on durability and fracture force.
MATERIALS AND METHODS
Specimens (n = 8 per group) were prepared from lithium disilicate (LS; IPS e.max, Ivoclar Vivadent) and advanced lithium disilicate (ALD; Cerec Tessera, Dentsply Sirona). Specimens were polished, and two-body wear test and thermocycling were performed (50 N, 120,000 cycles, 1.6 Hz, HO dist., 5°C/55°C, 600 cycles). Maximum vertical loss, surface roughness, surface roughness depth, and antagonist wear were determined. Single crowns (n = 8 per group; thickness 1.5 mm/1.0 mm) were manufactured from LS and ALD and mounted on human molar teeth with adhesive resin (AB; CalibraCeram, Dentsply Sirona), glass-ionomer cement (GIC; Ketac Cem, 3M ESPE), and hybrid glass-ionomer cement (HGIC; Calibra Bio, Dentsply Sirona). Thermocycling and mechanical loading (2 × 3000 × 5°C/55°C, 2 minutes, H0 dist., 1.2 × 10 50 N) were performed. Fracture force was determined by a universal testing machine (1446, ZwickRoell), and one-way analysis and Bonferroni post hoc test (α = .05) were used for statistical analyses.
RESULTS
Mean (ALD: 210 ± 42.4 μm; LS: 264.3 ± 56.1 μm) and maximum (ALD: 391.1 ± 86.3 μm; LS: 518.3 ± 113.2 μm) wear between groups were significantly different (P ≤ .047). Fracture force varied between 1,911.4 ± 468.4 N (ALD/AB 1 mm) and 2,995.3 ± 880.6 N (LS/GIC), without significant differences (P ≥ .152).
CONCLUSION
ALD showed better wear behavior than LS, but provided similar fracture force. Cementation and reduction of ceramic thickness had only minor effects on fracture force.
Topics: Humans; Mastication; Dental Porcelain; Ceramics; Glass Ionomer Cements; Materials Testing; Computer-Aided Design; Surface Properties
PubMed: 35234750
DOI: 10.11607/ijp.7820