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Biomedical subjects

M Bakke

Publications and source records attributed to M Bakke.

18 recordsLinked to original sources
PubMed1992

Histochemical characterization of masseter muscle fibres in a biopsy study of normal young women.

Muscle fibres from biopsies of the anterior part of the masseter muscle (pars superficialis) were histochemically characterized in 13 healthy female students. They were 21-28 yr old with a full complement of teeth, and normal facial and occlusal relations. Before surgery, normal masseter muscle function was demonstrated by bite-force measurements and recordings of electromyographic activity. After staining for myosin ATPase activity, the relative mean areas of muscle fibres were: type I 82.9%, type IM 9.5% and type II 8.3%. The intraindividual (18-155% of mean) and interindividual (0-216% of mean) variation of the fibre size was large. The type I fibres had the largest diameter (10-80 microns, mean: 39 microns), the type II fibres (6-47 microns, mean: 21 microns) and the IM fibres (8-54 microns, mean: 28 microns) the smallest. The biopsy technique and the histochemical characterization will be suitable for reference in women with functional changes or diseases of the masseter muscle.

Adult↗
PubMed1992

Occlusal control of mandibular elevator muscles.

Occlusal stability and mandibular elevator muscle function was studied in 25 women (20-30 yr of age). They had 27-32 fully erupted teeth with few treated occlusal surfaces, and craniomandibular function including mandibular mobility was normal. The aim was to analyze the influence of natural patterns of occlusal contact on electromyographic activity, unaffected by pain and functional disorders. Occlusal stability was assessed in the intercuspal and in lateral contact positions as the number of teeth with physical contact and the number of opposing pairs of teeth in contact. Electromyographic activity was recorded by surface electrodes over anterior and posterior temporalis and masseter muscles. In general, positive correlations were found between occlusal stability in intercuspal position and moderate to strong static and dynamic contractions, most significant in masseter muscles, indicating that forceful contraction of these muscles implies stable occlusion. Systematically, the duration of activity during chewing was negatively correlated with occlusal stability in the intercuspal position, most pronounced in working-side muscles. This pointed to shorter contractions with stable occlusion and is interpreted as the result of less need for stabilizing activity. It is concluded, that the correlations between occlusal stability and elevator muscle function are probably based on feedback mechanisms from periodontal pressoreceptors.

Adult↗
PubMed1992

Ultrasound image of human masseter muscle related to bite force, electromyography, facial morphology, and occlusal factors.

The thickness of the human masseter muscle, corresponding approximately to a cross-section at the most bulky part of the superficial portion, was measured by ultrasound scanning at three sites 1 cm apart. The study included 13 women, 21-28 yr of age, with a minimum of 24 teeth and without craniomandibular disorders. Ultrasonography produced a well-defined depiction of the muscle with distinct tendinous structures. The average thickness at the measuring sites varied from 8.83 to 11.08 mm with the muscle relaxed, and increased significantly during contraction to average values between 9.84 and 12.57 mm. The study showed a connection between measures of masseter thickness and function of the muscle, as well as parameters generally associated with masseter muscle function. Muscle thickness at the voluminous anterior part of the superficial portion was systematically and significantly correlated to bite force, occlusal tooth contact and cephalometric data (anterior face height, vertical jaw relation and mandibular inclination). In conclusion, ultrasound scanning gave an uncomplicated and a reproducible access to parameters of jaw muscle function and its interaction with the craniomandibular system.

Adult↗
PubMed1992

Craniomandibular disorders and masticatory muscle function.

The heading craniomandibular disorders covers a wide range of abnormal and pathologic conditions accompanied by orofacial pain and impaired mandibular function, the masticatory muscles and the temporomandibular joints being the structures most frequently involved. Prevalences of severe craniomandibular disorders accompanied by headache and facial pain urgently in need of treatment are 1-2% in children, about 5% in adolescents, and 5-15% in adults, with higher values in women than in men. With respect to physiology and ergonomics, masticatory muscles are comparable to other human skeletal muscles, e.g. of shoulder, neck and lower back. Therefore these muscles share pathogenesis, symptoms and signs of muscular disorders caused by prolonged, low-level static contractions or intermittent isometric contractions at higher levels. Since the same elements of performance in the masticatory muscles are influenced by occlusal factors, they link the development of muscular fatigue, discomfort and pain to the dental occlusion. Furthermore, changes of the occlusal surfaces, e.g. due to dental treatment, may influence the performance of the masticatory muscles, and consequently interfere with local muscular function.

Adolescent↗
PubMed1992

A novel 3',5'-cyclic adenosine monophosphate-responsive sequence in the bovine CYP17 gene is a target of negative regulation by protein kinase C.

The bovine 17 alpha-hydroxylase cytochrome P450 gene (CYP17) contains at least two cAMP-responsive sequences (CRS) within its 5'-flanking region. In this study it is demonstrated that one of the sequences, CRS1, is also a target for protein kinase C (PKC)-mediated regulation. Forskolin-induced, CRS1-dependent transcription of a heterologous minimal promoter/structural gene which had been transfected into the mouse adrenocortical tumor cell line Y1 was suppressed by activation of PKC by phorbol esters such as 12-O-tetradecanoyl phorbol-14-acetate and phorbol 12,13-didecanoate-beta (PDD beta). Use of the active and inactive forms of PDD (PDD alpha and PDD beta) as well as down-regulation of PKC by prolonged treatment of the cells with 12-O-tetradecanoyl phorbol-14-acetate demonstrated that the effect of phorbol esters on transcription conferred by CRS1 was mediated through the PKC pathway and not a consequence of general toxicity to the cells. Analysis of the different steps in the signal transduction pathway between the adenylate cyclase and the CRS1 element suggests that phrobol esters do not exert their effect by altering the forskolin-induced cAMP production, activation of PKA, or the binding of nuclear proteins to CRS1. These results establish the CRS1 element as a target not only for PKA, but also for the PKC-mediated signal transduction pathway. They further suggest that PKC interferes with the transcriptional activation competence of factors bound to CRS1 and the minimal promoter.

Animals↗
PubMed1991

Temporalis and masseter muscle activity in patients with anterior open bite and craniomandibular disorders.

Activity in temporalis and masseter muscles, and traits of facial morphology and occlusal stability were studied in 22 patients (19 women, 3 men; 15-45 yr of age) with anterior open bite and symptoms and signs of craniomandibular disorders. Facial morphology was assessed by profile radiographs, occlusal stability by tooth contacts, and craniomandibular function by clinical and radiological examination. Electromyographic activity was recorded by surface electrodes after primary treatment with a reflex-releasing, stabilizing splint. Maximal voluntary contraction was reduced compared to reference values, particularly in subjects with muscular affection, but maximal activity increased significantly when biting on the splint. Maximal voluntary contraction was positively correlated to molar contact and negatively to anterior face height, mandibular inclination, vertical jaw relation and gonial angle. Relative loading of the muscles was markedly increased during resting posture. It was concluded that reduced occlusal stability and long-face morphology were associated with weak elevator muscle activity with disposition overload and tenderness. The results also indicated that increase of occlusal stability might lead to increased muscle strength and possibly reduce risk of physical strain.

Adolescent↗
PubMed1991

[Functional and orthodontic treatment of a patient with an open bite craniomandibular disorder].

In a 21-year-old man with open bite, myogenic headache and internal derangement of the temporomandibular joint clinical examination was supplemented by radiographs of the joints, cephalometric analysis, electromyographic recordings of the masticatory muscles and tracking of mandibular movements. His condition was characterized by reduced occlusal stability with contact limited to posterior molars, and weak elevator muscles with increased strain during posture and chewing. The purpose of the treatment was to eliminate symptoms with a reflex-releasing stabilizing splint. Secondly, to increase occlusal stability, primarily with the splint and later through orthodontic treatment aiming at closing the bite in the premolar region because the reduced occlusal stability seemed to be a significant etiologic factor. Treatment with the splint reduced signs and symptoms of craniomandibular disorders. During the following orthodontic treatment, contact was established on both premolars and molars, mainly due to extrusion of mandibular premolars. Analysis showed greater elevator strength and decreased muscular loading after treatment. A splint was used for retention accompanied by muscle training with exercise gum. Permanent training with gum was recommended after the retention period.

Adult↗
PubMed1990

Facial growth and oral function in a case of juvenile rheumatoid arthritis during an 8-year period.

The present report is a detailed analysis of facial growth and oral function in a girl with juvenile rheumatoid arthritis of the temporomandibular joints. She was followed from 9 to 17 years of age prior to and after orthognathic surgery. Facial growth was assessed by facial photographs, dental casts, and roentgencephalometry, and oral function was assessed clinically by electromyography, kinesiography, and bite force. In addition, histological and histochemical analysis was performed on biopsy material from her masseter muscle obtained at the time of surgery. The study showed a clear relationship between facial growth and oral function. Dysplastic growth of the mandible led to an increasingly unstable occlusion with poor working conditions for the masticatory muscles. The muscles became weak, and even revealed marked structural histological and histochemical changes. Based on these observations it is suggested that the conventional treatment strategy with postponement of orthodontic or orthognathic surgical treatment until cessation of growth is abandoned and that early treatment should be undertaken to maintain occlusal stability throughout the growth period.

Arthritis, Juvenile↗
PubMed1990

Structure and function of masticatory muscles in a case of muscular dystrophy.

Histologic examination of muscle biopsies and functional examination comprising electromyography and force measurements in a 19-yr-old boy with muscular dystrophy showed different wasting patterns of mandibular elevator and depressor muscles. Pronounced histopathologic changes were present in the masseter muscle, whereas pathologic findings in the anterior digastric muscle were limited to increased number of cells in slightly enlarged interfiber connective tissue. The masticatory pattern was distorted, and strength of mandibular elevator muscles was less than one third of the norm, whereas depressor strength corresponded more to reference values. This difference of muscular wasting might be caused by protective enzymes in the digastric muscle and/or functionally induced damage of the masseter. As affection from muscular dystrophy may vary greatly between the masticatory muscles, structural and functional examination should be used routinely to clarify prognosis before initiation of treatment procedures.

Adult↗
PubMed1990

Unilateral, isometric bite force in 8-68-year-old women and men related to occlusal factors.

Unilateral bite force was studied in 63 women and 59 men, 8-68 yr of age. The subjects had a minimum of 24 teeth and no symptoms or signs of disorders of the craniomandibular system. Bite force was stronger in men (522 N) than in women (441 N). It increased with age until 25 yr (P less than 0.0001). The level decreased significantly after this age in women, whereas it only tended to decrease in men and not until after 45 yr of age. Body height was positively associated with force. However, the strongest correlation (r: 0.43-0.49, P less than 0.01) with adult bite force was occlusal contact. The normal bite-force values with important determining factors provide reference data for screening of elevator muscle strength in routine examination of craniomandibular function.

Adolescent↗
PubMed1989

Clinical significance of isometric bite force versus electrical activity in temporal and masseter muscles.

Bite force and activity in temporal and masseter muscles during biting and chewing were recorded in 19 control subjects and 23 subjects with symptoms and signs of functional disorders of the craniomandibular system. The entire group comprised 13 men and 29 women, 14-63 yr of age. Maximal unilateral bite force was 480 Newton (N) in control subjects and 387 N in patients, with corresponding bilateral values of 347 N and 230 N. At predetermined levels of contraction, temporalis and masseter activity were linearly related. Correlations of bite force and activity in short static contractions were significant with respect to unilateral, but not to bilateral force measurements. Only in the masseter muscle was strength of dynamic contractions during chewing significantly correlated to bite force. With the present method it was demonstrated that unilateral bite force is a simple clinical indicator of mandibular elevator strength as a whole, but inadequate to disclose asymmetric conditions. During isometric contraction, relative strength of electromyographic activity fairly accurately imaged the output of mechanical activity.

Adolescent↗
PubMed1989

Herbst treatment in late adolescence: clinical, electromyographic, kinesiographic, and radiographic analysis of one case.

In an almost full-grown male of 17 years, functional and morphological changes were followed during Herbst treatment and subsequent control. Retrognathism of the mandible was overcorrected, and then normalized by reverse headgear to the maxilla. Partial relapse due to insufficient cooperation during retention necessitated retreatment. Treatment resulted in marked dentoalveolar changes, increase in mandibular length and ramus height, apposition and remodelling of condylar heads and flattening of the temporal joint surface. After treatment masseter strength was 40 per cent reduced, probably due to prolonged hypofunction.

Activator Appliances↗
PubMed1988

Occlusal harmony and disharmony: frauds in clinical dentistry?

In defining the principles of occlusal function it is possible to demonstrate how firmly the number, the placement and the distribution of occlusal contacts control muscle activity and joint function during biting and chewing. This control implies that the intercuspal position is determined by positive feedback, that is by afferent activity that varies with occlusal stability. Conventional dental treatment involving occlusal surfaces alters this input and consequently alters the coordination of the muscles of mastication and the function of the temporomandibular joints. To assess and direct this input properly, quantitative parameters of electromyography and kinesiography are needed. Terms such as harmony and disharmony are irrelevant and must be abandoned.

Dental Occlusion↗
PubMed1976

Effect of acupuncture on the pain perception thresholds of human teeth.

The effect of acumpuncture on the pain perception threshold of maxillary incisors and canines as determined by a Bofors Pulp Tester was studied in 33 dental students 19-30 years of age. Test teeth were cleaned with pumice and 10% alcohol, air-dried, and insulated at the approximal surfaces with strips of rubber dam. Based on a comparison of bipolar and monopolar stimulation the latter method was chosen, with the cathode placed on the incisal third of the facial surface, the indifferent electrode in the subject's hand. In separate groups of subjects thresholds were assessed four times at intervals of 15 min without acupuncture (1), with acupuncture performed manually (2) and electrically (3), and during electrical stimulation with surface electrodes over acupuncture points (4). On separate days acupuncture and surface stimulation was applied unilaterally at the points S2 (cheek), Li4 (hand), or S44 (foot). Compared with control threshold (8.44 muA) acupuncture was accompanied by a small increase, most pronounced after 45 min (1.51 muA, P less than 0.0005). However, the hypalgesia observed was insufficient to justify acupuncture as a means of pain control in conservative dentistry.

Acupuncture Therapy↗