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Biomedical subjects

L Dahlström

Publications and source records attributed to L Dahlström.

33 records · Page 2Linked to original sources
PubMed1989

Perception of jaw position during different conditions.

The perception of jaw position, measured as the ability to produce a predetermined mandibular posture repetitively, was recorded under different experimental conditions. A control group of asymptomatic subjects was tested before and after anesthesia of the TMJs and after fatigue of the masticatory muscles. Groups of patients with craniomandibular disorders of arthrogenic or myogenic origin were also tested. None of the experimental variables affected position perception, and the patient groups did not differ from each other or the normal group in perception of jaw position. The possible clinical value of such recordings in differential diagnosis is therefore open to question.

Fatigue↗
PubMed1989

Variability in electromyographic surface recordings of the human masseter muscle.

Serial registrations of integrated unilateral surface masseter EMG were performed in eight healthy subjects in the rest position, during controlled gentle biting and during maximal clenching at five different sessions in order to analyse the variability. The recording conditions were standardised. The EMG activity for the group did not differ significantly between the sessions at any level but individual variations were great in the rest position both within and between days. Good consistency was found at controlled force levels. Temporally stable measurements of masseter activity which permit quantitative comparisons thus seem possible.

Adult↗
PubMed1988

Endurance tests of the masticatory system on different bite force levels.

Endurance tests of the masticatory system were performed in three different groups of healthy volunteers in order to investigate the relation between bite force and endurance time on different force levels. The subjects clenched a bite fork until exhaustion. Some tests were performed with and others without visual feedback of the exerted force. It was found that the subjects could sustain the maximal bite force practically at the same level during the recording time with visual feedback. The exerted force varied during the non-feedback recordings and generally decreased on the forceful levels. The average endurance time increased at lower bite force levels and the relation between force and endurance time is described. The average integrated time-force areas did not differ between the test levels. It is concluded that endurance tests in the clinic may be performed on submaximal bite force levels.

Adult↗
PubMed1986

Facial asymmetry and unstable occlusion due to poliomyelitis. Report of a case.

A case, referred to the Department of Stomatognathic Physiology, Göteborg, with an unstable occlusion is presented. There was a facial asymmetry and the bony morphology differed markedly between the sides. No EMG activity in the masticatory muscles could be detected on the left side. It was diagnosed as a probable sequela to poliomyelitis in the childhood. The impact of altered muscle function on the bony structures and dentition is discussed.

Adult↗
PubMed1985

Stress-induced muscular activity in mandibular dysfunction: effects of biofeedback training.

Surface electromyographic (EMG) recordings from the left and right masseteric areas during physical and psychological induced stress were obtained from 20 patients with mandibular dysfunction and 20 healthy controls. Integrated electromyographic activity was not significantly different for the two sides but was higher for patients than for controls during both stress and relaxation. Anxiety level, as measured with the Taylor Manifest Anxiety Scale, was higher for patients. Biofeedback treatment for the patients resulted in significantly reduced signs and symptoms of mandibular dysfunction. When the test procedures were repeated, the controls had not changed in their electromyographic responses during stress, whereas the patients showed a significant decrease in this respect. The results obtained are discussed in terms of a systems-oriented etiological concept.

Adult↗
PubMed1985

Relationship between myoelectric activity in masticatory muscles and bite force.

Myoelectric activity in the anterior and posterior temporalis and in the masseter muscle was assessed in five subjects biting unilaterally on a bite fork at 50, 100 and 200 N for 60 s. The bite fork was placed between the right first premolars and the first molars. The ipsilateral muscle activity was recorded first, and the contralateral side was evaluated 1 wk later. The relationship between exerted force and EMG-activity was expressed as ratios between EMG-activity and related bite force. EMG-activity increased with increasing force for all muscles tested. Linearity was found for the anterior temporal muscle, but not for the other muscles. Four of the subjects participated in an endurance test, exerting maximum bite force on the right side for as long as possible. The EMG activity of the right masseter muscle was closely related to bite force, in contrast to the other tested muscles. The activity of the left muscles increased at the end of the endurance test.

Adult↗
PubMed1985

Comparative electromyographic study of bite plates and stabilization splints.

The object was to study any influence on the integrated electromyographic activity in the masseter and temporal muscles of two types of occlusal appliances. Seventeen healthy subjects wore a bite plate with a frontal plateau and a full coverage stabilization splint at night, each for 1 wk. The EMG activity was recorded without appliances in situ, in the rest position, and during gentle and maximum biting before and after the use of the different appliances. After use of the bite plate, the EMG activity was not significantly different at any tested level. After use of the splint, the activity in the rest position was significantly lower in the anterior and posterior parts of the temporal muscles. The EMG activity was significantly lower in the rest position in both parts of the temporal muscle after use of the splint than after use of the bite plate. In a control group of eight subjects in whom no appliances were used, the EMG activity did not change significantly between the initial and 1- or 5-wk recordings. Thus, the occlusal design of the appliances seems to be of importance for the influence on the EMG activity in the masticatory muscles, at least in healthy subjects.

Adult↗
PubMed1985

Bite plates and stabilization splints in mandibular dysfunction. A clinical and electromyographic comparison.

Twenty patients with mandibular dysfunction, all women, aged 17-41 years, were randomized for treatment with either a bite plate with a frontal plateau or a full-coverage stabilization splint. The occlusal appliances were used at night for 6 weeks to compare clinical and electromyographic effects (EMGs). Integrated EMGs were recorded bilaterally from the anterior and posterior parts of the temporal muscle and the masseter muscle in the rest position and during gentle and maximal biting before and after treatment without the appliances in situ. Initially recorded EMG activity in the temporal muscle was correlated to signs of dysfunction in the rest position. Compared with previously investigated healthy subjects, the patients had lower EMG activity in the anterior part of the temporal muscle and in the masseter muscle during maximal biting. Use of occlusal appliances at night for 6 weeks did not change the EMG activity in the rest position or during maximal biting. The clinical signs improved, significantly in the splint group. The subjective symptoms improved in both groups, significantly more in the splint group.

Adolescent↗
PubMed1984

Clinical and electromyographic effects of biofeedback training in mandibular dysfunction.

Twenty patients with mandibular dysfunction, 10 acute and 10 chronic, were trained with electromyographic biofeedback from either m. masseter or m. frontalis area. The electromyographic activity in both muscle areas were recorded during six training sessions. The mean electromyographic activity decreased significantly within the sessions for both muscle areas, progressively more often for the m. masseter area. The activity did not decrease significantly between sessions for any muscle area. The clinical and subjective symptoms of mandibular dysfunction improved significantly after the training. No differences, electromyographically or clinically, among acute, chronic, m. masseter area, or m. frontalis area feedback patients could be observed. No correlation between decrease in electromyographic activity and symptoms could be established. Since a simplistic neuromuscular learning model for biofeedback training gains little support from these results, alternative views are discussed.

Adult↗
PubMed1984

Treatment of mandibular dysfunction: the clinical usefulness of biofeedback in relation to splint therapy.

The long-term treatment effects of biofeedback and occlusal splints on mandibular dysfunction were compared. Thirty female patients were randomly divided into two treatment groups. One group had full coverage splints, the other group received biofeedback training. At the re-examinations 1 and 12 months after completion of therapy, the subjective and clinical symptoms were significantly reduced in both groups. No significant differences between the groups were found. A stepwise analysis of regression indicated that biofeedback training may be a useful alternative to splint therapy in cases where night time bruxing is not the dominating feature.

Adult↗
PubMed1984

Conservative treatment of mandibular dysfunction. Clinical, experimental and electromyographic studies of biofeedback and occlusal appliances.

Two modes of treatment for mandibular dysfunction, electromyographic biofeedback and occlusal appliances, were studied. Thirty patients were randomly assigned to treatment with biofeedback or splints and it was shown that both therapies reduced signs and symptoms of mandibular dysfunction in the short and long-term perspective. An analysis of potentially useful clinical predictors of the treatment outcome indicated that laboratory diurnal biofeedback may be a useful alternative to splint therapy in cases where night-time bruxing is not the dominating feature. During biofeedback training, from the masseter or frontal muscle, the EMG activity in both muscle areas in 20 patients with acute or chronic mandibular dysfunction decreased within but not between six sessions, progressively more often for the masseter area. The results were valid irrespective of feedback or symptom duration. A simplistic neuromuscular learning model could not alone explain the positive effects on symptoms. It was shown that motivation was important. The EMG activity in the masseter area was greater during experimentally induced stress than under baseline or resting conditions, and greater in the patients than in matched controls. There was no difference between the pain side and the non-pain side. After the biofeedback training, the EMG activity during stress in the patients under identical conditions was lower and at the same level as in the controls, whose responsiveness had not changed. The anxiety level, expressed in TMAS scores, was greater in patients than in controls before but not after treatment. The influence on the integrated EMG activity in the masseter and temporal muscles after night-time use of appliances with different occlusal design was studied in 17 healthy subjects. After use of stabilisation splints, the activity in the temporal muscle was lower in the rest position and lower than after use of bite plates. The activity during gentle and maximal biting had not changed. The mean activity in a control group of 8 subjects had not changed at any functional level. A positive correlation between clinical signs and level of EMG activity in the temporal muscle in the rest position was observed in 19 patients with mandibular dysfunction. The patients also had less activity in the masseter and temporal muscles during maximal biting compared to healthy subjects. No change in EMG activity could be observed after night-time use of stabilisation splints or bite plates for six weeks, although the symptoms improved.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1982

Comparison of effects of electromyographic biofeedback and occlusal splint therapy on mandibular dysfunction.

In order to evaluate and compare the effects of biofeedback and occlusal splint therapy on mandibular dysfunction, 30 patients were randomly divided into two treatment groups. The patients were women aged 20--40 years without any obvious organic reasons for their symptoms. There were no significant differences between the two groups before the start of treatment in respect of signs and symptoms of mandibular dysfunction. One group used full coverage splints at night for 6 weeks. The other group received biofeedback training up to six times, 30 min per session. One month after completion of the therapy the patients were re-examined. Both groups showed a significant reduction in symptoms, both subjectively and clinically. No significant differences between the groups were found. The two treatments were thus equally effective in the short-term perspective in patients with signs and symptoms of mandibular dysfunction.

Adult↗