Effect of Mouth Opening on Bite-Force Discrimination

1988 ◽  
Vol 66 (1) ◽  
pp. 227-234 ◽  
Author(s):  
W. N. Williams ◽  
L. L. Lapointe ◽  
C. E. Cornell ◽  
G. E. Turner
Keyword(s):  
Strain Gauge ◽  
Mouth Opening ◽  
Normal Subjects ◽  
Difference Limen ◽  
Bite Force ◽  
Paired Comparisons ◽  
Modified Method ◽  
Resistance Forces ◽  
Maximum Opening ◽  
Method Of Constant Stimuli

The purpose of this study was to determine whether different extents of mouth opening affect normal subjects' ( N = 24; 12 women, 12 men) ability to discriminate differences in their interincisor bite force. Three mouth openings were selected including 50, 70, and 90 percent of maximum opening for each subject. Bite force was measured using a specially designed strain gauge scale which permitted subjects to monitor visually when their biting force equalled a preset resistance. Resistance forces of 500 and 1000 gm. were selected as standards. The procedure involved the use of a modified method of constant stimuli in which each subject was presented with a series of paired resistance settings, one at a time—the first resistance setting being the standard and the second resistance was the comparator. This paired-comparisons procedure was continued until the subjects' difference limen (DL) value (the threshold of discrimination between two forces) could be established. An analysis of variance yielded no significant differences in subjects' ability to discriminate bite force as a function of mouth opening.

Interdental Thickness Discrimination by Normal Subjects

1974 ◽  
Vol 53 (6) ◽  
pp. 1404-1407 ◽  
Author(s):  
William N. Williams ◽  
Leonard L. Lapointe ◽  
John I. Thornby
Keyword(s):  
Mouth Opening ◽  
Normal Subjects ◽  
Difference Limen ◽  
Relative Thickness ◽  
Perceptual Factors

Twenty-four adults made judgments of relative thickness of Plexiglas wedges placed inter dentally. Obtained difference limen values were consistently lower than those previously reported. Degree of mouth opening had no significant effect on performance. These data contribute to our understanding of sensory-perceptual factors in the regulation of chewing and speech.

scholarly journals Feeding mechanics and bite force modelling of the skull of Dunkleosteus terrelli , an ancient apex predator

2006 ◽  
Vol 3 (1) ◽  
pp. 77-80 ◽  
Author(s):  
Philip S.L Anderson ◽  
Mark W Westneat
Keyword(s):  
High Speed ◽  
Prey Capture ◽  
Mouth Opening ◽  
Biomechanical Model ◽  
Bite Force ◽  
Rapid Expansion ◽  
Large Individual ◽  
Linkage Mechanism ◽  
Feeding Mechanics ◽  
Four Bar Linkage

Placoderms are a diverse group of armoured fishes that dominated the aquatic ecosystems of the Devonian Period, 415–360 million years ago. The bladed jaws of predators such as Dunkleosteus suggest that these animals were the first vertebrates to use rapid mouth opening and a powerful bite to capture and fragment evasive prey items prior to ingestion. Here, we develop a biomechanical model of force and motion during feeding in Dunkleosteus terrelli that reveals a highly kinetic skull driven by a unique four-bar linkage mechanism. The linkage system has a high-speed transmission for jaw opening, producing a rapid expansion phase similar to modern fishes that use suction during prey capture. Jaw closing muscles power an extraordinarily strong bite, with an estimated maximal bite force of over 4400 N at the jaw tip and more than 5300 N at the rear dental plates, for a large individual (6 m in total length). This bite force capability is the greatest of all living or fossil fishes and is among the most powerful bites in animals.

Differential Sensitivity to Duration of Acoustic Signals

1966 ◽  
Vol 9 (3) ◽  
pp. 371-384 ◽  
Author(s):  
Howard B. Ruhm ◽  
Eugene O. Mencke ◽  
Braxton Milburn ◽  
William A. Cooper ◽  
Darrell E. Rose
Keyword(s):  
Normal Subjects ◽  
Acoustic Signals ◽  
Difference Limen ◽  
Differential Sensitivity ◽  
Signal Frequency ◽  
Concomitant Increase ◽  
Sensation Level ◽  
Cochlear Pathology ◽  
The Mean ◽  
Level Effect

Experiments were conducted to assess differential sensitivity to acoustic signal duration under various combinations of reference duration, sensation level, and signal frequency, and to determine whether hearing impairment, ostensibly due to cochlear pathology, affects such discrimination. The absolute DL (difference limen) was linear as a function of reference duration at both 10 dB and 50 dB sensation levels in normal subjects and in those with presumed cochlear pathology. When a 10 dB SL signal was used, the mean absolute DL increased at the rate of 2.63 msec per 100-msec increase in reference duration. A concomitant increase of 2.38 msec per 100-msec increase in reference duration was observed when a 50 db SL signal was employed. Neither the signal frequency nor the presence of sensorineural hearing loss affected the duration DL, whereas a sensation level effect was exhibited by both types of subject. A smaller limen was obtained at 50 dB SL than at 10 dB SL.

The position of the mandibular condyle at maximal mouth opening in normal subjects

1994 ◽  
Vol 52 (12) ◽  
pp. 1269-1272 ◽  
Author(s):  
Toshitaka Muto ◽  
Masanori Kohara ◽  
Masaaki Kanazawa ◽  
Johji Kawakami
Keyword(s):  
Mandibular Condyle ◽  
Mouth Opening ◽  
Normal Subjects ◽  
Maximal Mouth Opening

A MODIFIED METHOD FOR THE ANALYSIS OF URINARY 17-KETOSTEROIDS, PREGNANEDIOL AND PREGNANETRIOL BY GAS LIQUID CHROMATOGRAPHY IN NORMAL SUBJECTS AND SUBJECTS WITH VARIOUS ENDOCRINE DISORDERS

1967 ◽  
Vol 54 (1) ◽  
pp. 37-50 ◽  
Author(s):  
Roberto Rivera ◽  
Ralph I. Dorfman ◽  
Enrico Forchielli
Keyword(s):  
Liquid Chromatography ◽  
Normal Subjects ◽  
Endocrine Disorders ◽  
Gas Liquid Chromatography ◽  
Modified Method ◽  
Trimethylsilyl Ethers ◽  
Normal Males ◽  
Steroid Excretion ◽  
Urinary Steroid

ABSTRACT A modified method using gas-liquid chromatography (GLC) is described for the determination of androsterone*, aetiocholanolone, dehydroepiandrosterone, pregnanediol and pregnanetriol in the same urine aliquot. After sequential enzymatic hydrolysis and solvolysis, the urine extract is separated into 3 main fractions by silica gel column chromatography; one containing mainly the 17-ketosteroids, androsterone, aetiocholanolone and dehydroepiandrosterone; a second containing pregnanediol and the third pregnanetriol. After formation of the trimethylsilyl ethers (TMSi), the respective fractions are subjected to gas-liquid chromatography for quantitation. Tritiated androsterone, pregnanediol and pregnanetriol are added prior to extraction of the urines to check for recoveries. The method is specific and reproductible and is sufficiently sensitive to permit determination of urinary steroid excretion levels as low as 0.025 mg/24 hours. Results obtained with this method in the study of normal males and females and various pathological conditions are presented.

Comparisons of Two Variants of the Method of Constant Stimuli for Estimating Difference Thresholds

2009 ◽  
Vol 68 (4) ◽  
pp. 189-192 ◽  
Author(s):  
Einat Lapid ◽  
Rolf Ulrich ◽  
Thomas Rammsayer
Keyword(s):  
Visual Information ◽  
Pattern Discrimination ◽  
Duration Discrimination ◽  
Line Length ◽  
Difference Limen ◽  
Discrimination Experiment ◽  
Difference Thresholds ◽  
The Difference ◽  
Random Dot Pattern ◽  
Method Of Constant Stimuli

The two-alternative forced-choice (2AFC) and the reminder tasks are variants of the method of constant stimuli. One or the other task is usually employed for estimating the difference limen (DL) in psychophysical research. Lapid, Ulrich, and Rammsayer (2008) found that the 2AFC task yields larger DLs than the reminder task for duration discrimination judgments. The results of the present paper confirm that this discrepancy also generalizes to discrimination judgments about nontemporal, visual information (Experiment 1: Random dot pattern discrimination; Experiment 2: Line-length discrimination). It is argued that this discrepancy is related to the presentation order of the standard and the comparison stimulus.

Quantitation of pharyngeal motor function in normal human subjects

1975 ◽  
Vol 39 (4) ◽  
pp. 692-696 ◽  
Author(s):  
W. J. Dodds ◽  
W. J. Hogan ◽  
S. B. Lydon ◽  
E. T. Stewart ◽  
J. J. Stef ◽  
...  
Keyword(s):  
Motor Activity ◽  
Strain Gauge ◽  
Human Subjects ◽  
Normal Subjects ◽  
Motor Disorders ◽  
High Fidelity ◽  
Wave Speeds ◽  
Wave Duration ◽  
Catheter System ◽  
Normal Human

A need exists for accurate pressure recording of pharyngeal motor events. Results of this study indicate that accurate quantitation of pharyngeal motor activity is not possible using a water-filled catheter system, even when high infusion rates are used. An intraluminal strain gauge system, however, achieves high-fidelity recording. Quantitation of pharyngeal peristalsis using the intraluminal strain gauge system reveals peristaltic pressure amplitudes higher than those hitherto recorded. In normal subjects, peristaltic amplitude averages about 200 mmHg in the hypopharynx, complexes in one subject being as high as 600 mmHg. A zone of relatively low pressure exists in the oropharynx. Mean pharyngeal wave duration decreases progressively in an aboral direction, from 1.0 to 0.3 s, and peristaltic wave speeds range between 9 and 25 cm/s. Accurate quantitation of pharyngeal peristaltic variables provides the necessary basis for characterization and assessment of pharyngeal motor disorders.

scholarly journals Immediate Effect of Masticatory Muscle Activity with Transcutaneous Electrical Nerve Stimulation in Muscle Pain of Temporomandibular Disorders Patients

2020 ◽  
Vol 9 (10) ◽  
pp. 3330
Author(s):  
Susumu Abe ◽  
Akane Miyagi ◽  
Kaoru Yoshinaga ◽  
Yoshizo Matsuka ◽  
Fumihiro Matsumoto ◽  
...  
Keyword(s):  
Nerve Stimulation ◽  
Muscle Activity ◽  
Temporomandibular Disorders ◽  
Muscle Pain ◽  
Transcutaneous Electrical Nerve Stimulation ◽  
Mouth Opening ◽  
Bite Force ◽  
Global Rating ◽  
Masticatory Muscle ◽  
Electrical Nerve Stimulation

Transcutaneous electrical nerve stimulation (TENS) is a non-invasive treatment modality for acute and chronic pain. However, little information for muscle activity is available on the immediate effects of TENS in masticatory muscle pain related to temporomandibular disorders (TMDs). The present study aimed to evaluate the immediate effects of TENS treatment on TMD-related muscle pain. Thirty-six patients with TMD-related muscle pain and 39 healthy subjects served as TMD and control groups, respectively. For objective evaluations, maximum mouth opening, and maximum bite force were measured before and after TENS. The pain intensity was assessed according to a 100-mm visual analog scale (VAS). TENS was applied to painful muscles for 20 min with frequencies of 100–200 Hz. The treatment outcome was evaluated using Global Rating of Change (GRC) scales. In the TMD group, VAS values significantly decreased after TENS. Although there was significant increase in the maximum mouth opening after TENS for only TMD group, the maximum bite force of both groups was significantly greater after TENS. According to GRC scales, one patient with TMD-related muscle pain expressed negative feelings after TENS. Conclusively, TENS treatment might quickly relieve pain in masticatory muscles and improve masticatory functions in patients with TMD-related muscle pain.

Two Rapid Odor Threshold Methods Compared to a Modified Method of Constant Stimuli

2008 ◽  
Vol 1 (1) ◽  
pp. 16-23 ◽  
Author(s):  
Paul M. Wise ◽  
Nancy Bien ◽  
Charles J. Wysocki
Keyword(s):  
Odor Threshold ◽  
Modified Method ◽  
Method Of Constant Stimuli
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