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Biomedical subjects

L V Christensen

Publications and source records attributed to L V Christensen.

At least 91 records · Page 5Linked to original sources
PubMed1980

Some subjective-experiential parameters of experimental tooth clenching in children.

Twelve children, aged 9--14 years, exercised maximal voluntary tooth clenching until facial pains were experienced and could no longer be endured. The pains were localized in the masseter and temporalis muscles and, occasionally, in the supra-orbital region. After onset of clenching pains appeared, on average, in 49 s (pain threshold) and they could, on average, be endured for 118 s (pain tolerance). The pain threshold varied significantly between individuals, but not within individuals. The number of pain sites, and the number of teeth in contact during clenching, did not determine the moment of onset of pains, nor the ability to endure pains. The pain tolerance did not seem to be influenced by the pain threshold.

Adolescent↗
PubMed1980

Effects of an occlusal splint on integrated electromyography of masseter muscle in experimental tooth clenching in man.

Six male subjects exercised maximal voluntary tooth clenching until fatigue appeared in the masseter muscle and until pains and exhaustion of this muscle could no longer be endured; that is, the fatigue threshold and the pain tolerance of the muscle were determined in seconds. An occlusal splint was inserted and the clenching exercises were repeated. During these exercises, and also during 10s of clenching, the electrical activity in the masseter muscle was recorded by bipolar surface electrodes and linearly integrated. Use of the splint did not result in significant changes in the subjective sensations of onset of fatigue and endurance of pain. As the periods of clenching increased, after insertion of the splint, the electrical activity decreased consistently, and use of the splint caused a significant decrease in the electrical activity of the pain tolerance test. As induced by the splint, there was no orderly pattern in changes of the fatigue thresholds and pain tolerances in relation to changes in the electrical activities of these parameters. The mode of action of the splint, in reducing the muscle activity, might have been that of stretching the elevator jaw muscles beyond their resting length.

Adult↗
PubMed1980

Some electromyographic parameters of experimental tooth clenching in children.

Twelve children exercised maximal voluntary tooth clenching until pains appeared (pain threshold) in the right masseter muscle and could no longer be endured (pain tolerance). Concomitantly the integrated electrical activity of the muscle was determined as a ratio of the isometric muscle exercises. It is possible that the two exercises were accompanied by progressive muscle fatigue. While changes in the pain threshold could not be related to similar changes in the accompanying electrical muscle activity, the pain tolerance seemed to increase with a decrease in electrical muscle activity. To a large, but unknown, extent the pain threshold might have depended on psychological factors, rather than electrical muscle activity, whereas the pain tolerance to a large, but unknown, extent might have dependend on the electrical muscle activity. The muscle activity of the two subjective tests might have been influenced by the same physiological determinants, e.g. progressive muscle fatigue and ischaemia of the muscle tissue. The number of teeth in contact during the isometric muscle exercises and the size of the gonial angle of the mandible did not influence either the pain threshold and pain tolerance or the muscle activity of these tests.

Adolescent↗
PubMed1980

Cultural, clinical and physiological aspects of pain: a review.

A review is given of selected cultural, clinical and physiological issues pertaining to the human experience of pain. Special attention is devoted to the modern gate control theory of pain as it applies to the sensory pathways of the fifth cranial nerve; that is, facial pains and some of their associated symptoms and signs.

Attitude↗
PubMed1979

Some subjective-experiential parameters in experimental tooth clenching in man.

Experimental tooth clenching was performed by fourteen human subjects in order to determine the onset of the subjective sensations of jaw muscle fatigue and jaw muscle pains, the ability to endure jaw muscle pains, and other discomforts. During production of maximal voluntary isometric tension by the elevator jaw muscles the fatigue threshold (x = 31 s), the pain threshold (x = 55 s), and the pain tolerance (x = 118 s) of tooth clenching did not vary significantly intraindividually, whereas this was so interindividually. There might have existed psychological relationships between the three parameters, but they might also have been influenced by the same physiological cause. The weak to intense discomforts were localized to the face, and primarily to the jaw muscles, and after determination of the pain tolerance they disappeared in about 90 s.

Adult↗
PubMed1979

Influence of muscle pain tolerance on muscle pain threshold in experimental tooth clenching in man.

Ten adults and ten children exercised maximal voluntary tooth clenching until pains appeared in the jaw muscles, i.e. the muscle pain threshold of tooth clenching was determined. Subsequently, the subjects were instructed to exercise tooth clenching until they were forced to stop because of intolerable pains and exhaustion of the contracting muscles, i.e. the muscle pain tolerance of tooth clenching was recorded, and during these bouts of clenching the pain tolerance of tooth clenching was recorded, and during these bouts of clenching the pain threshold was also determined. In adults, determination of the pain tolerance decreased the pain threshold by 19%, and in children it either decreased the pain threshold by 20% or increased it by 56%. It is proposed to introduce the muscle pain tolerance of tooth clenching as an adjunct in the clinical examination of cases of facial pains presumed to originate from the jaw muscles, but the test should be interpreted with caution.

Adolescent↗
PubMed1978

The concept of the sagittal condylar guidance: biological fact or fallacy?

The clinical concept of a sagittal condylar guidance pertaining to the human temporomandibular joint is discussed in the light of selected studies on the anatomy, radiography and cineradiography of this joint, and clinical attempts at recording a sagittal condylar guidance. It seems as if there is no single and well defined sagittal condylar guidance in vivo, and thus no single and well defined sagittal condylar guidance angle applicable to the adjustable articulator.

Cineradiography↗
PubMed1978

Mast cells in masseter muscle in experimental bruxism in man.

Three human subjects performed tooth grinding for 25 min, and after 20 h biopsies of the right and left masseter muscles were examined for their contents of mast cells. In comparison with specimens from a control group of three subjects, there was an increase of degranulating mast cells in muscles that had performed bruxism.

Adult↗
PubMed1976

Mandibular kinesthesia in fatigue of human jaw muscles.

Fatigue was developed by four human subjects after negative work, and by two subjects after negative/positive work by the jaw muscles. Another four subjects did not develop fatigue subsequent to muscular exercise. In subjects with fatigue, the ability to perceive and/or produce repetitively a predetermined mandibular posture, i.e. mandibular kinesthesia, was impaired by about 285%. It is suggested that the distorted kinesthesia resulted from either a fatigue-induced failure of, or a fatigue-induced persistence of, jaw muscle fibers to contract, which in turn led to distorting flows of afferent impulses from muscles spindles and/or tendon organs.

Adult↗
PubMed1976

Facial pain in negative and positive work of human jaw muscles.

Ten healthy human male subjects with a mean age of 21 years performed negative and negative/positive work with the jaw muscles for about 21 min. The average amount of negative work was 13.3 kgm, while that of negative/positive work was 48.5 kgm. Eight subjects developed either spontaneous or provoked facial pain subsequent to the exercise. No positive correlations were demonstrated between the total number of facial pain sites and the amounts of work and power of the muscles, nor between the number of pain sites and the speed of mandibular movement. It is suggested that the appearance of facial pain was associated with the pre-experimental strength and conditioning of the jaw muscles.

Adolescent↗
PubMed1975

Clinical kinesthetic experiments on the lateral pterygoid muscle and temporomandibular joint in man.

The possible kinesthetic function of proprioceptors in the lateral pterygoid muscle was clinically assessed after anesthesia of muscle and temporomandibular joint receptors, respectively. A mandibular posture was actively and repetitively produced with an average accuracy of 2.5 mm, while the accuracy decreased by about two-fold after narcotization. It is suggested that muscle spindles in the lateral pterygoid muscle as well as mechanoreceptors in the temporomandibular joint capsule are active in the perception and/or control of mandibular postures.

Adult↗