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Biomedical subjects

G T Clark

Publications and source records attributed to G T Clark.

At least 109 records · Page 6Linked to original sources
PubMed1985

Electromyographic study of human jaw-closing muscle endurance, fatigue and recovery at various isometric force levels.

The effect of a sustained isometric clenching, at various force levels or maximum voluntary bite-force levels, was evaluated on normal jaw-function subjects. Surface electromyographic (EMG) recordings of the masseter and temporalis were taken and bite force was measured using an intra-oral force transducer placed unilaterally in the 2nd premolar-1st molar region. Subjects sustained isometric force at the 25, 50, 75 and 100 per cent force level. Maximal bite force and EMG contraction levels were measured before, during and after these sustained isometric tasks. Subjects showed no change in their brief maximal contraction or force levels during or after various fatigue-inducing isometric tasks. The findings suggested a lack of contractile failure in the jaw-closing muscles. Pain intolerance rather than neuromuscular fatigue is the limiting factor of a sustained submaximal or even maximal clenching effort.

Adult↗
PubMed1984

Interdental thickness discrimination in myofascial pain dysfunction subjects.

Interdental thickness discrimination (ITD) was evaluated on twenty-eight normal subjects and twenty subjects with myofascial pain dysfunction (MPD). This evaluation was performed before and after a submaximal isometric clenching task sustained to pain tolerance. The results of the study demonstrate a significant difference in ITD ability at several test points between the normal and MPD subjects. The experimental variable of sustained submaximal clenching did not significantly alter the ITD ability of either subject group.

Adult↗
PubMed1984

The effect of sustained submaximal clenching on maximum bite force in myofascial pain dysfunction patients.

The effect of a sustained (30% maximum) isometric clenching task on the maximum voluntary bite force level was evaluated on normal jaw function subjects as well as on abnormal jaw function subjects (MPD patients). The results indicate that the MPD subjects had a lower maximum voluntary bite force level and a shorter endurance time when compared to normal subjects. Neither the control subjects nor the MPD subjects demonstrated a change in their brief MVBF after a 'fatigue inducing' task. These results suggest a lack of contractile element failure in the jaw closing muscles following sustained submaximal isometric clenching on a force transducer.

Adult↗
PubMed1984

A critical evaluation of orthopedic interocclusal appliance therapy: effectiveness for specific symptoms.

This paper reviews the effectiveness of occlusal splints on specific symptoms that are often associated with TM disorders. The research has shown the clicking TMJ is sometimes helped but not cured by the traditional stabilization interocclusal appliance and that TMJ clicking is the least responsive to treatment. Questions have been raised about the need to specifically treat the clicking joint; more research on this issue is necessary. Painful TMJs have been shown to respond to occlusal appliance therapy, but questions still exist about the effectiveness of interocclusal appliances for this symptom. There is little scientific proof available about the ability of splints to effectively slow down or reverse degenerative TMJ changes that are evident on radiographs. Masticatory muscle pain is by far the symptom that has the best experimental evidence to support occlusal splints as a highly effective method of treatment. These changes are probably mediated via an alteration in the patient's muscle activity patterns. Those patients with more severe symptoms are less likely to be helped with splints as a sole treatment modality. The effect of occlusal appliances in muscle trismus has been discussed but not effectively evaluated in the literature. Occlusal splints have been shown to have a distinct influence on improving mandibular muscle coordination. Inter-occlusal splints are a commonly used method of controlling attrition and adverse tooth loading, and few questions have been raised in the literature about this therapeutic application.

Bruxism↗
PubMed1984

A critical evaluation of orthopedic interocclusal appliance therapy: design, theory, and overall effectiveness.

Orthopedic interocclusal appliances have been evaluated in a number of research papers and clinical reports over the years. Various theories have been proposed about the method of action of the different appliances, but at present no conclusive controlled testing of these theories has occurred. Certainly, when the potential influence of the nonspecific treatment factors is considered, as well as those cognitive awareness factors common to all appliances, the use of "symptom improvement" as the definitive proof of the need for mandibular realignment or repositioning must be questioned. Specific, well-controlled research using more quantifiable measures of the treatment effect is necessary to make valid comparisons between the different therapeutic approaches. The full-arch occlusal stabilizing appliance is the design that has the most valid evidence about its effectiveness. Partial coverage interocclusal appliances have significant irreversible complications with tooth intrusion or eruption when used on an extended basis. There is little or no experimental support at present about repositioning, realignment, and pivot appliances and their effectiveness. Therefore, these appliances must be considered experimental treatments. When used to treat TM dysfunction in a program along with other methods, such as occlusal adjustments, and prosthetic care, the effectiveness of this treatment method is between 70% and 90%. As a general approach to managing TM pain and dysfunction, interocclusal appliances appear to be a highly effective, commonly used method.

Dental Occlusion↗
PubMed1983

Factors influencing the excitatory-masseteric reflex evoked by gingival electrical stimulation in man.

An excitatory-masseteric reflex response was evoked by electrical gingival stimulation in five subjects; the reflex had an onset latency of 7.6 ms with a SD of 0.7 ms. The response occurred just prior to the silent or inhibitory period. There was consistent post-inhibitory synchronization of the EMG activity record in all subjects. Several methods were used to demonstrate this short-latency reflex. The first was to average non-rectified EMG activity. The second was to increase the number of receptors which are simultaneously activated by using multiple electrodes so that a greater area of gingiva could be stimulated. A third was to increase the level of excitability of the motoneurons in the masseteric pool by increasing voluntary bite force. Fourthly, the excitatory reflex was evoked during increased-excitatory drive to the pool, with the additional feature that the reflex appeared at a time when no ongoing EMG activity was present in the masseter muscle. Little doubt should now remain concerning the existence of a short latency excitatory reflex from intra-oral receptors to masseteric motoneurons in man.

Adolescent↗
PubMed1981

Management of muscular hyperactivity.

A treatment plan for jaw pain and dysfunction due to muscular hyperactivity can only be formulated after the exclusion of systemic disease or an inflammatory condition as a possible cause thorough physical examination of the head and neck and the study of an appropriate radiographic survey. The treatment plan should consist of a series of progressively graded stages which must be fully explained to the patient. This will reduce the problem of overtreatment and maintain the confidence of the patient in the dentist should the early conservative measures by unsuccessful. The level at which a patient will be entered upon the treatment ladder will vary with the severity of the presenting symptoms. The usual stages will include the following: (a) elimination or neutralization of the cause, (b) initial conservative treatment involving prescription of a mild anti- inflammatory analgesic, soft diet, rest, moist heat and where indicated an anxiolytic drug such as Valium, (c) exercise to stretch muscles and remobilize the joint, (d) physical therapy including diathermy, (e) stress control treatment and relaxation training and, finally (f) referral to a centre for chronic pain relief. Advice is given on the management of a patient who either discontinues treatment or for whom complete remission os symptoms is not possible.

Humans↗
PubMed1980

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↗