Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “MASTICATION”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 1,495 records · Page 83Linked to original sources
PubMed1995

Effects of protein deficiency and diet consistency on the parotid gland and parotid saliva of rats.

Protein deficiency results in an increased susceptibility to dental caries, suggesting that oral host-defense properties are compromised. An important component of oral host defense is salivary gland function, which is affected by both protein deficiency and diet consistency. This study describes the effects on rat parotid gland growth and secretory function induced by feeding rats diets of normal (20%) or moderately low (7%) protein content, provided in either a powdered or solid form. In addition, since protein deficiency may result in a secondary zinc deficiency which, in turn, may affect salivary gland function, the effects of these diets on liver zinc concentration were also measured. From 22 to 47 days of age, rats (18/group) were fed the following diets: normal protein, powdered; normal protein, solid; low protein, powdered; and low protein, solid. With each diet consistency, liver zinc was higher for the normal protein group. Within each protein level, liver zinc was higher for the solid diet. This latter observation suggests that food mastication and the resultant stimulation of salivary gland function may also play a role in zinc metabolism. With the normal-protein diet, parotid gland weight was higher for the solid diet; with the low-protein diet, parotid gland weight was similar for both consistencies and did not differ from that of the group fed the "normal protein, powdered" diet. For both consistencies, parotid saliva protein concentration was greater for malnourished rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1999

The smallest detectable difference of mandibular function impairment in patients with a painfully restricted temporomandibular joint.

Mandibular functions such as speech, laughing, yawning, mastication, and taking a large bite may be impaired if temporomandibular disorders exist. The Mandibular Function Impairement Questionnaire is a validated instrument that scores perceived difficulty of representative mandibular functions in relation to jaw complaints. However, the reliability of the Mandibular Function Impairment Questionnaire has never been adequately tested. Generalizability and decision studies are currently proposed to assess the reliability of a measurement device. The smallest detectable difference is the smallest statistically significant amount of change to be detected with a measurement device. The purpose of this study was to assess the reliability of the Mandibular Function Impairement Questionnaire in terms of the smallest detectable difference. Twenty-five consecutive patients with painfully restricted temporomandibular joints completed the Mandibular Function Impairement Questionnaire on two separate measurement days, one week apart, using two consecutive sessions per day. Spearman's r was calculated for test-retest reliability. Variance components such as patients, measurement days, repetitions, and all their interactions were analyzed in the generalizability study. In the decision study, the smallest detectable difference was calculated for different days and repetitions. Spearman's r varied from 0.69 to 0.96. The between-patient variance and the error variance contributed 81% and 19% to total variance, respectively. The Mandibular Function Impairment Questionnaire is a reliable instrument for the assessment of mandibular function impairment. The minimal amount of change to be detected is 14 units on a scale of 0 to 68. Reliability in terms of the smallest detectable difference increases if the measurement is repeated twice on two separate days: The smallest detectable difference improves to 10 units.

Adult↗
PubMed1988

Functional restoration after subtotal glossectomy and laryngectomy.

Extensive resection of carcinoma that involves the tongue base and supraglottic larynx is accompanied by significant potential morbidity and mortality. This is often indicated by poor rates of cure and the limited palliation afforded by radiotherapy alone. Removal of a significant portion of the posterior tongue frequently results in intractable aspiration. Techniques in reconstruction of the oropharyngeal defect and tongue base have included primary closure, random flaps, and myocutaneous flaps. Each of these techniques has been successful, to some degree, in resurfacing pharyngeal defects. However, the functional results in regard to deglutition are less than satisfactory as a result of aspiration. Frequently, simultaneous or delayed total laryngectomy is performed to deal with the pulmonary complications. Various types of laryngoplasty do not uniformly correct the problems of aspiration and deglutition associated with subtotal glossectomy. Our experience includes eight patients who had advanced squamous cell carcinoma of the tongue base, vallecula, and the supraglottic larynx. All patients underwent partial or subtotal glossectomy and laryngectomy. The mucosal defect was reconstructed with pectoralis myocutaneous flap. In order to reestablish voice, a primary tracheopharyngeal shunt was created with the use of a portion of cricoid and upper trachea. The majority of these patients have had successful rehabilitation of deglutition, mastication, and speech.

Carcinoma, Squamous Cell↗
PubMed2000

Biomechanics of the mandible.

In this review the biomechanical behavior of the mandibular bone tissue, and of the mandibular bone as a whole, in response to external loading is discussed. A survey is given of the determinants of mandibular stiffness and strength, including the mechanical properties and distribution of bone tissue and the size and shape of the mandible. Mandibular deformations, stresses, and strains that occur during static biting and chewing are reviewed. During biting and the powerstroke of mastication, a combination of sagittal bending, corpus rotation, and transverse bending occurs. The result is a complex pattern of stresses and strains (compressive, tensile, shear, torsional) in the mandible. To be able to resist forces and bending and torsional moments, not only the material properties of the mandible but also its geometrical design is of importance. This is reflected by variables like polar and maximum and minimum moments of inertia and the relative amount and distribution of bone tissue. In the longitudinal direction, the mandible is stiffer than in transverse directions, and the vertical cross-sectional dimension of the mandible is larger than its transverse dimension. These features enhance the resistance of the mandible to the relatively large vertical shear forces and bending moments that come into play in the sagittal plane.

Animals↗
PubMed2002

Task-dependence of activity/ bite-force relations and its impact on estimation of chewing force from EMG.

Estimation of chewing force from electromyograms (EMGs) calibrated in isometric biting yielded strikingly high force values. We tested the hypothesis that EMG-based force predictions are excessive because of differing activity/bite-force relations in mastication and isometric biting. In nine patients, unilateral bite forces and EMGs of 4 elevator muscles were recorded during chewing and isometric clenching on a bite-fork. We estimated chewing force by substituting chewing EMGs of each muscle into isometric activity/bite-force regressions. The estimates were compared with actual chewing forces recorded by intra-oral transducers. In all muscles except the balancing-side masseter, the activity/bite-force ratio was significantly higher in chewing than in isometric biting. The actual mean chewing force amounted to 220 N, while EMG-based estimates ranged from 273 to 475 N, depending on the muscle used for estimation. The results indicate that different activity/force characteristics in dynamic and isometric biting can cause overestimation when chewing force is predicted from masticatory EMGs.

Algorithms↗
PubMed2003

Food texture differences affect energy metabolism in rats.

Dietary factors such as taste and nutrients are known to affect satiety and energy balance. We hypothesized that food texture might contribute to the regulation of energy metabolism through the process of mastication in the oral cavity as well. The effects of long-term feeding of different-textured pellets on body weight gain, adiposity, and thermogenesis were assessed. From weaning at 4 wks, rats were divided into 2 groups fed on either standard (controls) or soft pellets (soft-fed) that required less chewing with the same nutritional composition. At 26 wks, the soft-fed rats showed greater adiposity than did the controls. Daily food intake did not differ between the 2 groups. The increase in body temperature following feeding was significantly lower in the soft-fed rats. These results suggested that food texture affected energy metabolism by changing post-prandial thermogenesis. The long-term deficiency of thermogenesis associated with soft foods resulted in a greater tendency toward obesity.

Adipose Tissue↗
PubMed2003

Age-related changes in brain regional activity during chewing: a functional magnetic resonance imaging study.

Age-related changes in mastication-induced brain neuronal activity have been suggested. However, in humans, little is known about the anatomical regions involved. Using fMRI during cycles of rhythmic gum-chewing and no chewing, we have examined the effect of aging on brain regional activity during chewing in young adult (19-26 yrs), middle-aged (42-55 yrs), and aged (65-73 yrs) healthy humans. In all subjects, chewing resulted in a bilateral increase in the BOLD signals in the sensorimotor cortex, cerebellum, thalamus, supplementary motor area, and insula, and a unilateral increase in the right prefrontal area. In the first three regions, the signal increases were attenuated in an age-dependent manner, whereas, in the right prefrontal area, the converse was seen. The remaining two regions showed no significant differences with ages. These results indicate that chewing causes regional increases in neuronal activity in the brain, some of which are age-dependent.

Adult↗
PubMed2004

Relationship between oral sensitivity and masticatory performance.

The size of a bolus determines how it will be manipulated in the mouth and swallowed. We hypothesized that mucosal sensitivity would be important for masticatory function. The accuracy of solid object size perception, spatial acuity, and food particle size reduction during mastication were measured in 22 healthy adults with/without topical anesthesia of their oral mucosa. Topical anesthesia had no effect on the perception of sphere sizes, but significantly reduced spatial sensitivity. Without anesthesia, there was a correlation between an individual's ability to perceive the sizes of steel spheres (diameter, 4-9 mm) and the sizes of food particles chewed for 15 cycles and at swallowing. There was no correlation between spatial sensitivity and food particle size. We suggest that the stimuli used to test two-point discrimination stimulates only superficial receptors, which involve light touch and are easily anesthetized, while the spheres might excite more deeply-set receptors. The latter appear to be more important for masticatory performance and swallowing.

Adult↗
PubMed2005

Cyclic motion of the soft palate in feeding.

The soft palate moves rhythmically during feeding, but the timing and frequency of this motion are not known. We tested the hypothesis that cyclic soft palate motion is temporally linked to cyclic jaw movement. Nine healthy, asymptomatic human subjects with normal dentition ate solid food coated with barium. Videofluorographic recordings showed that rhythmic motions of the soft palate during mastication were linked temporally to jaw motion. Soft palate motion occurred in every recording but not in every jaw cycle. The soft palate moved upward as the jaw opened, but the nasopharynx was not sealed. During swallowing, however, the soft palate invariably elevated during the intercuspal phase of jaw motion, sealing the nasopharynx. The frequency of soft palate cycles was lowest early in a feeding sequence and gradually increased as the sequence progressed from ingestion to swallowing. We conclude that cyclic movement of the soft palate in feeding is temporally linked to jaw motion.

Adult↗
PubMed2002

Reflex control of human jaw muscles.

The aim of this review is to discuss what is known about the reflex control of the human masticatory system and to propose a method for standardized investigation. Literature regarding the current knowledge of activation of jaw muscles, receptors involved in the feedback control, and reflex pathways is discussed. The reflexes are discussed under the headings of the stimulation conditions. This was deliberately done to remind the reader that under each stimulation condition, several receptor systems are activated, and that it is not yet possible to stimulate only one afferent system in isolation in human mastication experiments. To achieve a method for uniform investigation, we need to set a method for stimulation of the afferent pathway under study with minimal simultaneous activation of other receptor systems. This stimulation should also be done in an efficient and reproducible way. To substantiate our conviction to standardize the stimulus type and parameters, we discuss the advantages and disadvantages of mechanical and electrical stimuli. For mechanical stimulus to be delivered in a reproducible way, the following precautions are suggested: The stimulus delivery system (often a probe attached to a vibrator) should be brought into secure contact with the area of stimulation. To minimize the slack between the probe, the area to be stimulated should be taken up by the application of pre-load, and the delivered force should be recorded in series. Electrical stimulus has advantages in that it can be delivered in a reproducible way, though its physiological relevance can be questioned. It is also necessary to standardize the method for recording and analyzing the responses of the motoneurons to the stimulation. For that, a new technique is introduced, and its advantages over the currently used methods are discussed. The new method can illustrate the synaptic potential that is induced in the motoneurons without the errors that are unavoidable in the current techniques. We believe that once stimulation, recording, and analysis methods are standardized, it will be possible to bring out the real "wiring diagram" that operates in conscious human subjects.

Afferent Pathways↗
PubMed2006

Quantitative analysis of the variability of unilateral chewing movements in young adults.

Kinesiography can be used as a diagnostic tool in a dental clinic context. In the current study, a kinesiograph was used to detect and record the three-dimensional motion of the mandibular mid-incisor point during unilateral chewing as a function of time. The aim of the study was to quantify the within-subject short-term reproducibility of the kinesiographic recordings in normal, healthy subjects. Ten seconds of unilateral (right and left) gum chewing were recorded in 20 control subjects using computerized kinesiography. Each subject performed 18 chewing sequences (three repetitions x three sessions x two sides). Chewing cycle duration, volume, standardized depth and width, and the number of reversed cycles were calculated. Intraclass correlation coefficients (two-way random effects analysis of variance with interactions) and paired t-tests were used to compare sessions. For each subject and side, chewing variability was expressed as the coefficient of variation (percentage ratio of standard deviation to mean) of each variable. Mean left and right side mastications were computed over all sessions and subjects. For all the analyzed variables, larger variations between subjects (analysis of variance, p < 0.001) than between sessions were found, with intraclass correlation coefficients ranging between 0.432 (left side cycle duration) and 0.989 (right side standardized width). No systematic errors between the three measurement sessions were found for cycle volume and shape (paired t, p > 0.05). The highest between subjects/ between sessions variance ratios (up to 223.28) were found for cycle duration and shape. In all subjects, chewing cycle volume was very variable, with mean coefficients of variation up to 47% (left side in females). Cycle duration and standardized depth and width were more reproducible, with mean coefficients of variation up to 10% (duration), 14% (standardized width), and 18% (standardized depth). The spatial characteristics of gum chewing cycles had a large within-subject variability. The temporal and size-standardized (shape) characteristics were more consistent within subject. The results should allow selection of a set of relatively more consistent variables for the definition of normality and the comparison of patients.

Adult↗
PubMed2000

Three-dimensional loading and growth of the zygomatic arch.

Despite a number of previous biomechanical studies on the zygomatic arch, unanswered questions remain about its three-dimensional loading and growth. Using young miniature swine, we have for the first time recorded strains from both the medial and lateral aspects of the squamosal bone during mastication and masseter muscle stimulation. Strains from the zygomatic bone flange and zygomatic arch growth data were also obtained from the same animals. A second study on a younger group of animals examined the growth of the zygomatic flange following partial removal of the masseter. Strain data indicated that the squamosal bone is bent out-of-plane and that this pattern of loading is quite different from that of the adjacent zygomatic bone, which experiences much lower strains with little evidence of out-of-plane bending. Surprisingly, strains were higher in the zygomatic flange during contralateral chews and contralateral masseter stimulations than during ipsilateral chews/stimulations. These strains proved to arise from movement of the condyle, explaining why partial removal of the masseter had little effect on the growth of the flange. Other growth results indicated an approximately threefold greater rate of subperiosteal deposition on the lateral surface of the squamosal bone than on the zygomatic bone. This difference in growth rate is attributed to the presence of sutures that contribute to the lateral displacement of the zygomatic bone but not the squamosal bone. This explanation does not exclude the possibility that the rapid apposition on the lateral squamosal surface is regulated by the high surface strains that result from out-of-plane bending.

Animals↗
PubMed1976

[Behavioral pharmacology of berberine-type alkaloids. (1) Central depressive action of Coptidis rhizoma and its constituents].

Coptis root is frequently utilized as a sedative in Chinese medicines, however, the central depressant action of this compound has not been reported. Such being the case, the central depressant actions of methanol extract of coptis root, its active ingredients such as non-alkaloids fraction, tertiary base fraction, quarternary base fraction, magnoflorine fraction, berberine hydrochloride, coptisine hydrochloride and the extract from SAN O SHA SHIN TO being one of the preparations which contain coptis root were investigated in mice. The antigastric ulcer action of these substances was also examined in rats. All substances were given orally. Sontaneous movement and coordinative motor activity were not depressed by methanol extract, non-alkaloid fraction quarternary base fraction, magnoflorine fraction, berberine hydrochloride, coptisine hhdrochloride and the extract from SAN O SHA SHIN TO. There was no inhibition of chemical- and electro-shock-induced convulsion, morphine induced Straub's tail reaction, apomorphine-induced masticating motion and aggressive behavior induced by electrical stimulation. A loss of righting reflex due to hypnotics was not potentiated by the substances. The quarternary base fraction did not elicit central depression, while the tertiary base fraction slightly depressed the function of the central nervous system. Quarternary base alkaloids such as berberine exerted a slight antiulcer effect.

Agonistic Behavior↗
PubMed1997

Examining patients' responses about the effectiveness of five denture adhesive pastes.

In this clinical trial, the authors evaluated the responses of 25 experienced denture wearers in regard to the effectiveness of five denture adhesive pastes. The patients responded to questions about the effect of the pastes on quality and duration of retention as well as on mastication. Subjects were also asked which product they considered to be best. Eighteen (72 percent) of the 25 subjects rated Secure (John O. Butler Co.) denture adhesive paste best overall.

Adhesives↗
PubMed2006

On the role of the pontine brainstem in vocal pattern generation: a telemetric single-unit recording study in the squirrel monkey.

In a recent study, we localized a discrete area in the ventrolateral pontine brainstem of squirrel monkeys, which seems to play a role in vocal pattern generation of frequency-modulated vocalizations. The present study compares the neuronal activity of this area with that of three motoneuron pools involved in phonation, namely the trigeminal motor nucleus, facial nucleus, and nucleus ambiguous. The experiments were performed in freely moving squirrel monkeys (Saimiri sciureus) during spontaneous vocal communication, using a telemetric single-unit recording technique. We found vocalization-related activity in all motoneuron pools recorded. Each of them, however, showed a specific profile of activity properties with respect to call types uttered, syllable structure, and pre-onset time. Different activity profiles were also found for neurons showing purely vocalization-correlated activity, vocalization- and mastication-correlated activity, and vocalization- and respiration-correlated activity. By comparing the activity properties of the proposed vocal pattern generator with the three motoneuron pools, we show that the pontine vocalization area is, in fact, able to control each of the three motoneuron pools during frequency-modulated vocalizations. The present study thus supports the existence of a vocal pattern generator for frequency-modulated call types in the ventrolateral pontine brainstem.

Animals↗
PubMed2001

Analysis of histochemically and morphometrically in the anterior belly digastric muscle of osteopetrotic (op/op) mice.

The fibers of the anterior belly digastric muscle of mice, fed a granulated diet for various periods, have been studied histochemically and morphometrically. The diameters of the anterior belly digastric fibers in normal mice fed only a granulated diet were smaller than those in mice fed a solid diet. Differences in the succinate dehydrogenase (SDH) activity of muscle fibers between op/op and normal mice gradually appeared in the anterior belly digastric muscle and, by the age of 90 days, under-development of muscle fibers was observed in the mild-belly region of the anterior belly digastric muscle of op/op mice fed a granulated diet. These results indicate mechanical stress in mastication plays an important role in the development of the anterior belly digastric muscle structures.

Animals↗
PubMed2006

Electromyographic analysis of the orbicularis oris muscle in oralized deaf individuals.

Electromyography has been used to evaluate the performance of the peribuccal musculature in mastication, swallowing and speech, and is an important tool for analysis of physiopathological changes affecting this musculature. Many investigations have been conducted in patients with auditory and speech deficiencies, but none has evaluated the musculature responsible for the speech. This study compared the electromyographic measurements of the superior and inferior fascicles of the orbicularis oris muscle in patients with profound bilateral neurosensorial hearing deficiency (deafness) and healthy volunteers. Electromyographic analysis was performed on recordings from 20 volunteers (mean age of 18.5 years) matched for gender and age. Subjects were assigned to two groups, as follows: a group formed by 10 individuals with profound bilateral neurosensorial hearing deficiency (deaf individuals) and a second group formed by 10 healthy individuals (hearers). Five clinical conditions were evaluated: suction, blowing, lip projection and compression, and production of the syllable "Pa". It was found that the deaf patients presented muscle hyperactivity in all clinical conditions, and that the inferior fascicle of the orbicularis oris muscle showed higher electromyographic activity rates, suggesting the need for a hearing-speech treatment with emphasis on oral motricity.

Adolescent↗
PubMed1989

[Experimental studies concerning the effect of food consistency on masticatory movement in man].

The purpose of this study is to investigate the relationship of food consistency to patterns of mandibular movement and jaw muscle activity during mastication in adults with normal dentitions. Ten young people who ranged in age from 23 to 26 were studied. Specially made chewing gums of 3 graded consistencies (4.4 x 10(2), 1.4 x 10(4), 1.3 x 10(5) poise), not contain any additive like sugar and flavor, were used as test foods. Mandibular movements were recorded and analyzed using a Mandibular Kinesiograph (Myotronics Research Co.) during chewing of the 3 grades of chewing gums for 40 strokes. Surface EMG signals were also recorded from the bilateral masseteric and anterior temporal muscles. Displacement and velocity of jaw movement, duration of each phase, and amount of EMG activity were then statistically compared among chewing trials of the 3 grades of chewing gums with two way analysis of variance. The results were as followed. With the increase of consistency of chewing gum; 1. Maximal vertical, antero-posterior and lateral displacements were significantly increased (p less than 0.01). 2. Maximal opening and closing velocities were significantly increased (p less than 0.01). 3. Opening phase time was significantly increased while occlusal phase time was significantly decreased (p less than 0.01). Cycle time and closing phase time were about constantly. 4. Burst duration, interval and cycle time were about constantly. 5. Burst activity were significantly increased (p less than 0.01). 6. Burst co-ordination pattern was about constantly.

Adult↗