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Biomedical subjects

W N Williams

Publications and source records attributed to W N Williams.

At least 19 recordsLinked to original sources
PubMed1992

Level of accuracy and degree of precision in attempting to maintain steady levels of biting force.

The primary purpose of this study was to assess the level of accuracy (bias) and degree of precision for a group of 24 normal subjects attempting to maintain a constant biting force at levels of 100 gm, 500 gm, 1000 gm and 2000 gm for a period of 10 s each. Accuracy is defined as the difference between subjects' actual level of biting force and the target value they were trying to achieve. Precision is the level or range of variability demonstrated by the subjects while attempting to bite with a constant level of force. Subjects' performance relative to accuracy and precision was also compared when using the central incisors vs. the first permanent molars. Assessment of bite force was measured using a specially designed strain gauge scale which permitted subjects to visually monitor when their biting force equalled a preset resistance. Each subject was instructed to bite on the end of a plastic sheathed steel beam with enough force to activate the indicator needle on the voltage meter to its central position and to try to maintain a constant level of biting force (by attempting to keep the indicator needle steady in its central position). No significant (P > 0.05) differences were found in mean accuracy in bite force for gender or specific teeth used in the biting task. However, a significant difference (P < 0.0001) in mean accuracy in bite force was found to exist between the target levels.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Fluoroscopy and nasoendoscopy in designing palatal lift prostheses.

Prosthodontists frequently provide prostheses for the management of speech disorders related to palatopharyngeal dysfunction. Optimal prosthetic management of the palatopharyngeal port requires close interaction between the prosthodontist and speech pathologist in the use of videofluoroscopy and videonasoendoscopy for design, placement, and modification of the prosthesis. Function of the palatopharyngeal port during production of controlled samples of connected speech can be observed from multiview fluoroscopy, including lateral and frontal projections. Like fluoroscopy, nasoendoscopy can be used to observe and record function of the palatopharyngeal port during speech. This article provides an overview of the procedures suggested for diagnosing palatopharyngeal disorders. A method for designing and placing a prosthesis to aid in obturating the nasopharynx is also suggested.

Endoscopy↗
PubMed1991

Team acceptance of specific recommendations for the treatment of VPI as provided by speech pathologists.

This retrospective study describes the frequency of one team's acceptance of speech pathologists' recommendations for specific secondary treatment procedures for the correction of VPI for 100 consecutive patients. In addition, assessment was made of the level of success in eliminating VPI relative to treatments utilized that were recommended by speech pathologists versus level of success when treatment other than that recommended by speech pathologists were used. For the 78 patients who received the treatment procedure recommended by speech pathologists, only 10 percent continued to demonstrate any clinically significant residual speech problem associated with VPI. However, for the 22 patients who received treatment other than that which had been recommended, 32 percent continued to demonstrate clinically significant speech problems associated with VPI. Data is presented on the success rate for correcting VPI relative to specific treatment recommendations including pharyngeal flap, palatal pushback, pharyngeal wall implant, tonsillectomy, prosthetic palatal lifts, and speech therapy.

Clinical Protocols↗
PubMed1991

Human pinch-force discrimination.

Pinch-sustaining tasks such as holding a pencil, fork, or key require the exertion of different levels of force. There is little information concerning normal subjects' ability to discriminate differences in their pinching force, so the purpose of this study was to evaluate the ability of 24 normal young women to discriminate differences in their self-generated isometric tip and lateral pinching force. Resistance forces of 10, 25, 50, and 75% of known normal maximum pinching force were selected as standards. Subjects were presented a series of paired resistance settings of which the first resistance in each pair was the standard and the second resistance a comparator of some greater amount. This procedure of paired comparisons was continued until subjects' threshold of discrimination between two pinching forces was established. The results indicated that subjects' pinch-force discrimination at the standard of 50% of reported maximum pinching force was significantly better for the tip condition than for the lateral condition. This study has described an instrumentation and the methodology for assessing individuals' ability to discriminate differences in their pinching force at submaximal levels.

Adult↗
PubMed1989

The effect of experimental anesthetization of the temporomandibular joint superior cavity on bite force discrimination.

The purpose of this study was to determine whether bilateral experimental sensory impairment of the temporomandibular joints (TMJs), as induced by injecting 1.5 ml of two percent mepivacaine into the superior cavity of the TMJs would alter the subject's ability to discriminate among differences in their bite force. Assessment of bite force was measured isometrically, using the strain gauge scale, and isotonically, using the mechanical swing beam scale. Resistance forces of 500 and 1000 gms were selected as standards. For each task, subjects were given a series of paired resistance settings, one at a time, the first of each pair being the standard resistance and the second being a comparator resistance of some greater amount. Subjects reported whether biting against the comparator resistance was equal to, greater than, or less than the standard resistance. This procedure of paired comparisons was continued until the subject's threshold of discrimination (difference limen value) between two biting forces was established. The results revealed that the subject's ability to discriminate differences in their bite force, either isometrically or isotonically, was not significantly (p greater than 0.05) affected following anesthetization of the superior cavity of the TMJs. These findings suggest that the sensory receptors within the TMJ capsules are not significantly involved in the detection of forces that play a role in monitoring biting force.

Adult↗
PubMed1989

Human bite force discrimination using specific maxillary and mandibular teeth.

The purpose of this study was to determine whether performance differences existed in subjects' self-generated bite force discrimination ability using maxillary and mandibular central incisors, canines, premolars and first molars. Two separate studies were conducted: (i) to assess whether performance differences existed in subjects' bite force discrimination ability using central incisors and premolars; (ii) to compare subjects' performance on bite force discrimination using central incisors, canines and first molars. Assessment of bite force was measured using a specially designed strain gauge scale allowing subjects to visually monitor when their biting force equalled a preset resistance. Resistance forces of 500, 1000 and 3000 g were selected as standards. Subjects were presented with a series of paired resistance settings, one at a time, the first of each pair being the standard and the second being the comparator setting of a predetermined amount. This paired-comparisons procedure was continued until the subjects' difference limen (DL) value (the threshold of discrimination between two forces) could be established. The first study revealed no significant (P greater than 0.05) overall difference in subjects' bite force discrimination ability relative to specific teeth. In contrast, in the second study a significant difference (P less than 0.05) was identified in subjects' performance relative to specific teeth; subjects' performed better using central incisors compared to first molars. In both studies, subjects' performance was significantly better (P less than 0.05) using the 500 g standard compared to the 3000 g standard in the first study, and compared to the 1000 g standard in the second study. No significant differences (P greater than 0.05) were observed between the performance of males and females in either study.

Adult↗
PubMed1988

Bilabial compression force discrimination by human subjects.

This study examined and compared bilabial compression force difference limen (DL) values (the minimally perceivable difference between two compression forces) for a group of twenty normal-speaking female subjects (mean age, 25 years) under conditions with and without the teeth clenched. In addition, measures of maximum bilabial compression force under conditions with and without the teeth clenched were obtained. Mean DL values obtained against a standard of 100 gm were 36 gm for the clenched condition and 38 gm with no clenching. Discrimination performance under these two conditions was not significantly different (P greater than 0.05). Mean maximum bilabial compression force was 411 gm with the teeth clenched and 568 gm without clenching. This difference in performance was significant (P less than 0.01). This study provides initial normal data against which individuals with labial sensorimotor dysfunction can be compared.

Adult↗
PubMed1988

Effect of mouth opening on bite-force discrimination.

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.

Adult↗
PubMed1987

Lingual numbness and speech articulation deviation associated with temporomandibular joint disk displacement.

A prospective investigation of 208 patients with painful, arthrographically verified temporomandibular joint disk displacement revealed that seven patients (3%) demonstrated lingual numbness associated with speech articulation impairment. The speech disorder was characterized primarily by a distortion in the production of /s,r,d, and t/. The lingual numbness and the speech disorder had in all cases started in association with a painful onset of permanent displacement of the temporomandibular joint disk. Local anesthetic blocking of the auriculotemporal nerve eliminated both joint pain and muscle pain and normalized tongue sensitivity and speech articulation. Placebo injections of saline solution resulted in no change. The explanation of the phenomenon is that the course of the lingual nerve for these seven patients was through the lateral pterygoid muscle rather than mesial to the muscle bundles and that an arthrokinetic myospasm resulted in compression of the lingual nerve. In order to test the hypothesis that the condition of lingual nerve entrapment in the lateral pterygoid muscle does exist, the course of the nerve was studied at dissection in 52 specimens from 26 cadaver heads. In 49 of the specimens, the lingual nerve descended deep to the lateral pterygoid muscle as has been traditionally defined. However, in three specimens, the nerve passed through the inferior belly of the muscle, revealing the condition of lingual nerve entrapment.

Adult↗
PubMed1987

Lateral and anterior-posterior mandibular position discrimination by normal subjects.

This study examined and compared lateral and anterior-posterior (A-P) mandibular position discrimination for a group of twenty normal subjects (mean age = 26 years). A specially designed and constructed sliding scale required subjects to position their mandible precisely in the horizontal plane and to try to discriminate differences in the control of their mandibular position. The results revealed that subjects are more sensitive in detecting changes in the lateral positioning of their mandible than in the A-P positions. Subjects' difference limen (DL) values (threshold of discrimination between two positions) in detecting changes in mandibular position to the right of centre was 1.59 mm, and to left of centre was 1.41 mm. Subjects' DL values obtained with the mandible forward, and back of, the reference position were 1.39 and 2.61 mm respectively.

Adult↗
PubMed1987

The effect of periodontal bone loss on bite force discrimination.

This study compared bite force discrimination between 14 treated periodontal patients with significant bone resorption and 14 control subjects who were free of periodontal disease. Bite force was measured using a strain gauge scale which permitted subjects to visually monitor when their bite force equaled a preset resistance. A bite force of 500 gm was selected as the standard. Subjects were presented with a series of paired resistance settings, one at a time, the first of each pair being the standard and the second being the comparator setting of some predetermined different amount. This procedure was continued until the subject's difference limen (DL) value, the threshold of discrimination between two bite forces, was established. The periodontal patients required an average of 334 additional grams of resistance over the standard before they could detect a difference, whereas the control subjects required only 201 additional grams. These group means were significantly different (P less than 0.01). The results of this study suggest that the periodontal ligament provides sensory feedback relative to bite force discrimination.

Adult↗
PubMed1986

Obstructive sleep apnea following treatment of velopharyngeal incompetence by Teflon injection.

From 1967 to 1974 a clinical trial of Teflon injection into the posterior pharyngeal wall for correction of velopharyngeal incompetence (VPI) was conducted in thirty-six patients. Six years after Teflon injection, one of the patients reported the onset of severe snoring punctuated by silences when he seemed not to be breathing, daytime hypersomnolence, and tiredness severe enough to interfere with work and studies. The diagnosis of obstructive sleep apnea (OSA) was confirmed by polysomnographic sleep monitoring, and the dynamics of the obstruction elucidated by cinefluoroscopy performed with the patient asleep. Resection of the lower 3/4 of the Teflon pad, leaving the upper rim to avoid recurrence of his VPI, has eliminated the symptoms of OSA and produced an improvement in his polysomnographic findings.

Adult↗
PubMed1985

Bite force discrimination by individuals with complete dentures.

The purpose of this study was to determine whether differences existed in interincisor bite force discrimination between a group of subjects wearing complete dentures and a group of dentate individuals. It was hypothesized that biting force is monitored at least in part by the sensory mechanism within the PDL and that the absence of the PDL would result in reduced bite force discrimination. A specially designed strain gauge scale was constructed for the measurement of bite force. Bite force discrimination was assessed at three different standards including 500, 1000, and 3000 gm. Data analysis revealed that, overall, bite force discrimination was not significantly different for the two groups. However, at the lightest standard of 500 gm, the dentate group performed significantly better (p less than .05) than the denture wearers. It is concluded that the sensory system within the PDL plays a role in monitoring bite force discrimination.

Adult↗
PubMed1985

Assessment of lingual function when ankyloglossia (tongue-tie) is suspected.

Dental specialists are frequently confronted with the task of attempting to determine whether a cause and effect relationship exists between a short or restricting lingual frenum (ankyloglossia or tongue-tie) and a specific oral motor dysfunction. Because there is no standardized definition of what constitutes a condition of tongue-tie, the dental practitioner is often unsure as to the appropriate course of action with a patient with suspected ankyloglossia. This paper describes clinical measures that permit quantifying several anatomic and functional aspects of the tongue. Such baseline analysis provides a more definitive appraisal of lingual function as well as a more objective basis for making pre- and posttreatment comparisons.

Child↗
PubMed1984

Human discrimination of different bite forces.

Twenty young adult subjects were selected to determine normal baseline data of dynamic interdental bite force discrimination by use of a specially designed strain gauge instrument. The data may aid in defining the role of the periodontal ligament, temporomandibular joint and muscles of mastication in the regulation of interincisor bite force.

Adult↗
PubMed1982

Comparison of sign versus verbal symbol training in retarded adults.

Sign language as an alternative or as an augmentive system to verbal language training in the mentally retarded is in widespread use. This study began an exploration of the relationship between sign and verbal learning in 10 institutionalized severely mentally retarded adults. Three experimental groups were taught color labels. Three persons received sign training only, 4 more received verbal training only, and last 3 received combined verbal and sign training. Sign labels tended to be learned more efficiently than verbal labels by this small group. Combined sign and verbal training improved verbal learning whereas sign learning was not improved through the combined approach. Replication and extension of this preliminary work with a larger and more representative sample is needed.

Adult↗