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Biomedical subjects

J D Rugh

Publications and source records attributed to J D Rugh.

At least 73 records · Page 4Linked to original sources

The effect of posterior tooth form on the chewing cycle in the frontal plane.

The present study found that the closing angle 2 mm from intercuspal position was independent of artificial posterior tooth forms for the eight subjects who wore remote overdentures. This closing angle may be dependent on occlusal morphology in dentulous subjects. The difference could be related to the amount of proprioceptive input available from mechanoreceptors in the periodontal ligament. In edentulous subjects other parameters of chewing cycles may be dependent on posterior tooth forms. The studies cited, as well as the present one, have not provided adequate information regarding posterior tooth form, patient preferences, and masticatory function. More research is needed with larger numbers of subjects, one set of denture bases with interchangeable posterior segments, and double-blind examiners. Then dentists should be better equipped to solve and treat their patients' problems.

Adult↗

Nocturnal muscle activity in the edentulous patient with and without dentures.

Nocturnal oral activity was evaluated in four complete denture wearers by means of masseter muscle EMG measurements. Patients who had worn dentures that were judged satisfactory for at least a 1-year period were selected. EMG levels were compared when subjects slept with and without the dentures in the mouth. All subjects showed a decrease in the integrated muscle activity while wearing the dentures. Additional studies need to be directed at understanding the mechanism of the effect of denture wearing on nocturnal muscle activity.

Denture, Complete↗

Survey of bruxism in an institutionalized mentally retarded population.

Bruxism was assessed in a population of 358 institutionalized mentally retarded individuals using two independent indexes: toothwear and staff reports. Bruxism based upon toothwear was found in 58%. Bruxism identified by staff reports was found in 41% of the population. No sex differences were observed. Three bruxer subgroups were identified: daytime only (17%), night only (8%), and day and night (16%). Older residents were more likely to grind their teeth than were younger residents. These results, when compared with other reports, suggest that bruxism is more likely to occur in the institutionalized mentally retarded population than in the nonretarded population.

Adolescent↗

Mandibular rest position in subjects with high and low mandibular plane angles.

Studies have explored the relationship between different facial morphologies and mandibular posture; however, few conclusions can be drawn. The purpose of this study was to explore the effects of contrasting facial morphologies on both clinical and electromyographic rest positions of the mandible. Electromyographic and clinical rest positions were recorded in 10 subjects whose Frankfort horizontal-to-mandibular plane angles were less than 20 degrees (low-angle group) and in 10 whose angles were greater than 30 degrees (high-angle group). The vertical dimension of clinical rest position was recorded from soft tissue markings on the nose and chin after subjects wet their lips, swallowed, and pronounced Mississippi. Electromyographic rest was defined as the interincisal vertical dimension of minimal muscle activity as determined with an Enting Model 220 EMG integrator and the Myotronics K-5 kinesiograph. Head posture was held constant to the subject's visual axis. The vertical dimension of clinical rest position was significantly greater in the low-angle group (X = 4.6 mm., S.D. = 1.4) than in the high angle group (means = 3.1 mm., S.D. = 1.1); however, no differences were observed in the EMG rest positions, which were 9.9 and 9.7 mm., respectively, for the low- and high-angle groups. These results do not support a simple mechanical explanation of jaw posture; however, these measurements need to be repeated with subjects selecting their preferred head inclination.

Adolescent↗

Clinical work posture for the dentist: an electromyographic study.

The results of this study suggest that lumbar support is a significant factor in reducing muscle activity of the upper and lower back for the dentist practicing sit-down dentistry. The importance of lumbar support should be emphasized in any criteria listing correct work posture for the dentist. Under the conditions of this study, stool heights did not influence muscle activity significantly, but did suggest a trend in considering problems of the lower back posture--low stool heights (90 degrees and 75 degrees) produced lower activity than a high stool height (105 degrees) if the back was supported. Therefore, in regard to muscle activity, results of this study suggest that the dental operator should sit low with the lumbar support always in contact with the lower back.

Back↗

Temporal analysis of nocturnal bruxism during EMG feedback.

Several studies have demonstrated that nocturnal bruxism and related symptoms can be relieved through nocturnal electromyogram (EMG) feedback. The effects, however, are not always long lasting and the mechanism of suppression is not understood. It was the object of this study to examine more closely the manner in which nocturnal feedback works in suppressing bruxism. Chart recordings were made of nocturnal masseter EMG activity in five bruxism subjects. Baseline recordings were made in the subject's home followed by 10 or more nights of feedback treatment. Treatment involved sounding a 300 mW tone when EMG activity exceeded about 20 micro V for more than 1 second. All subjects showed a decrease in the duration of bruxism. The decrease in bruxism was due to a reduction in the duration of bruxism episodes rather than a change in the number of episodes, i.e. rather than reducing the probability of an event starting, nocturnal feedback appears to simply suppress the activity once it is initiated. This provides little evidence of learning.

Adult↗

Psychological stress in orofacial neuromuscular problems.

Several forms of treatment for orofacial neuromuscular problems are based on the hypothesis that muscle hyperactivity due to psychological stress is a key factor in the aetiology. This paper reviews the evidence for this belief and describes the results of a study of muscular activity over a prolonged period by means of a portable battery powered electromyographic recording apparatus. In earlier studies of nocturnal masseter muscle activity ther was found a correlation between nocturnal bruxism and reports of stress. More recent studies covering activity for 24 hours per day have suggested that periods of muscle hyperactivity are correlated with specific daily activities but that there is great variability between patients. It is not yet possible to determine whether the patient's report of anxiety is the result or the cause of the orofacial muscular pain problem. It is evident that other parameters require evaluation.

Electromyography↗

Nocturnal masseter muscle activity and urinary catecholamine levels in bruxers.

Nocturnal electromyographic recordings of masseter muscle activity were performed on 20 bruxist and ten control subjects. Each subject collected two 24-hour urine samples. An analysis of urinary catecholamine content was performed. A positive relationship was found between increased epinephrine content and high levels of nocturnal masseter muscle activity.

Bruxism↗

Nocturnal electromyographic evaluation of myofascial pain dysfunction in patients undergoing occlusal splint therapy.

Twenty-five patients with symptoms of myofascial pain and abnormal jaw function were treated with use of a full arch maxillary occlusal splint. The level of nocturnal activity of the masseter muscle was monitored as were symptoms before, during, and after occlusal splint therapy. A decreased nocturnal EMG level during treatment was noted for 52% of the patients. A return to pretreatment EMG levels after removal of the splint was noticed in 92% of the patients; in 28% no change was shown and in 20%, an increase was shown in nocturnal EMG levels. The splint was most likely to reduce nocturnal EMG levels in patients with least severe symptoms.

Adult↗

Inexpensive technique to record respiration during flight.

This paper describes the development and use of a small (19 X 11 X 18 cm) tape recording system designed to monitor respiratory patterns during flight. This lightweight system (1.85 kg) was developed for less than $200 using commerically available subassemblies. Respiratory patterns are detected via a comfortable intranasal thermometer, amplified, and converted to an FM signal for taping. The device will also convert the tape recorded signal to a graphic display on a laboratory strip chart recorder. Reliable recordings of respiratory rate and respiratory regularity have been made in ambient temperatures of up to 43 degrees C. Chart recordings of student pilots' respiratory patterns at different stages of flight are presented. With modifications to the transducer assembly and amplifier, the basic recording system may be used to monitor other biological functions such as EMG, GSR, EEG, and ECG. Environmental variables have a frequency of less than 250 Hz (wind velocity, temperature, noise, etc.) may also be recorded with proper transducers.

Aerospace Medicine↗

Psychological implications in temporomandibular pain and dysfunction.

1. Although psychological factors are an important etiological component in producing and perpetuating TMJ disorders a comprehensive view of the problem can be best understood through the concept of multifactorial etiology. 2. Psychological factors operative in TMJ disorders cannot be understood within any single frame of reference. It is appropriate to examine emotional, behavioral, and interpersonal relationships in parallel, not as dichotomous concepts. 3. The symptom complex defined in this review as "TMJ disorders" is the musculoskeletal component of a larger group of microtraumatic signs and symptoms, all of which are manifestations of a generalized injury-producing activity termed dysfunction. 4. More explicit diagnoses need to be identified if definitional problems involving TMJ disorders are to be overcome. 5. Classical psychoanalytic conceptualization of the etiology of TMJ disorders has not been systematically examined, but has been widely accepted and found clinically useful by some therapists. 6. Clinical impressions notwithstanding, there is little evidence to indicate that TMJ disorders are correlated with one specific personality trait. Perhaps more definitive assessments will reveal uniform personality characteristics in subclasses of TMJ patients. 7. Emotional factors (e.g., anxiety, fear, frustration, and anger) play a significant role in the etiology of TMJ disorders, in that they elicit muscular tension and oral habits. Although it would appear unlikely that emotionally induced muscle activity is a "necessary" factor, it is probable that it will be found a "sufficient" cause for TMJ disorders. 8. Learning principles, should not be considered as an alternative etiological position but should be viewed as a framework upon which any psychological theory of etiology must be based. 9. The presence of chronic pain in TMJ patients may be of as much clinical significance in the prognosis as the physical findings associated with the disorder itself. 10. The potential placebo effect resulting from any treatment, coupled with other nonspecific effects of the doctor's attitudes, remains a powerful tool that can be utilized in treating TMJ disorders. A vital ingredient in the placebo effect is the quality of the doctor-patient relationship. 11. Patient evaluation should not only include a) a search for the immediate organic stimulus or biomechanical disturbance, but also b) an assessment of situational or chronic anxiety and other emotional factors and c) an observation of interpersonal styles of behavior commonly associated with the chronically sick patient. 12. Unilateral etiological views of TMJ disorders and rigid treatment approaches need modification. Treatment involving simultaneous dental and psychological approaches appears to have more promise.

Anxiety↗

Nocturnal electromyographic evaluation of bruxism patients undergoing short term splint therapy.

Eight confirmed bruxist subjects were investigated using portable electromyographic equipment. Nocturnal masseteric muscle activity, as measured by electromyography, was reduced immediately following the insertion of a full arch maxillary stabilization splint. It remained low until the splints were removed, at which time all but one subject's EMG values returned to pretreatment levels. Although the short-term spling therapy did not show a permanent reduction in EMG levels, a dramatic reduction has been demonstrated during treatment.

Adult↗