Article

Mandibular elevator muscles: Physiology, action, and effect of dental occlusion

Department of Oral Function and Physiology, School of Dentistry, Faculty of Health Sciences, University of Copenhagen, Copenhagen, Denmark
European Journal Of Oral Sciences (Impact Factor: 1.73). 09/1993; 101(5):314 - 331. DOI: 10.1111/j.1600-0722.1993.tb01127.x

ABSTRACT In spite of differences in embryologic origin, central nervous organization, and muscle fiber distribution, the physiology and action of mandibular elevator muscles are comparable to those of skeletal muscles of the limbs, back, and shoulder. They also share the same age-, sex-, and activity-related variations of muscular strength. With respect to pathogenesis, the type of muscular performance associated with the development of fatigue, discomfort, and pain in mandibular elevators seems to be influenced by the dental occlusion. Clinical research comparing the extent of occlusal contact in patients and controls as well as epidemiologic studies have shown reduced occlusal support to be a risk factor in the development of craniomandibular disorders. In healthy subjects with full natural dentition, occlusal support in the intercuspal position generally amounts to 12–14 pairs of contacting teeth, with predominance of contact on first and second molars. The extent of occlusal contact clearly affects electric muscle activity, bite force, jaw movements, and masticatory efficiency. Neurophysiologic evidence of receptor activity and reflex interaction with the basic motor programs of craniomandibular muscles tends to indicate that the peripheral occlusal control of the elevator muscles is provided by feedback from periodontal pressoreceptors. With stable intercuspal support, especially from posterior teeth, elevator muscles are activated strongly during biting and chewing with a high degree of force and masticatory efficiency, and with relatively short contractions, allowing for pauses. These variables of muscle contraction seem, in general, to strengthen the muscles and prevent discomfort. Therefore, occlusal stability keeps the muscles fit, and enables the masticatory system to meet its functional demands.

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Available from: Merete Bakke, Apr 09, 2014
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    • "Several historical and more recent studies, where occlusal parameters were analyzed , suggested that the activity of the masticatory muscles at maximum efforts depends on occlusal factors such as the numbers of posterior occlusal contacts (Helkimo et al., 1977; Bakke, 1993; Kerstein, 2004). A higher number of posterior contacts gives a stable intercuspal support that allows elevator muscles to achieve higher levels of muscular activity during clenching and chewing (Bakke, 1993; Kerstein, 2004). Moreover, alteration of the activity of temporalis and masseter were observed during clenching and chewing in presence of experimental occlusal interferences or prematurities . "
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    ABSTRACT: This study evaluated the influence of two different occlusal indicators (articulating papers of 40μm and 200μm) on muscular activity of the temporalis anterior (TA) and superficial masseter (MS) during maximum voluntary clenches (MVC), using surface electromyography (SEMG). It was hypothesized that an articulating paper positioned between dental arches during MVC elicits a different muscular activity compared with the occlusion on natural dentition (without the occlusal indicator). 30 healthy adult subjects with a complete, natural dentition were recruited; SEMG activity was recorded in the following experimental conditions: MVC with cotton rolls for standardization purposes; MVC on natural dentition; MVC onto the 40μm or 200μm paper indicator positioned on right or left side of the dental arch. Percentage Overlapping Coefficient (POC; separate values obtained for TA and MS), antero-posterior coefficient (APC) and total muscle activities (IMP) were the analyzed SEMG parameters. The use of an occlusal indicator statistically changed POC_TA, POC_MS and IMP median values (p<0.05). Both 40μm and 200μm occlusal papers did not significantly affect APC values (P=0.86). A pronounced asymmetric muscular activity has been recorded with the introduction of an interocclusal media. All indices of muscular activity did not differ between sexes (Kruskal Wallis test, P>0.05). In conclusion, the examined articulating papers affected two specific SEMG parameters (POC and IMP); the recorded muscular activity with the occlusal indicator varied regardless left or right side positioning, and independently from tested paper thicknesses. Copyright © 2015 Elsevier Ltd. All rights reserved.
    Journal of Electromyography and Kinesiology 04/2015; DOI:10.1016/j.jelekin.2015.04.006 · 1.73 Impact Factor
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    • "In addition, torque and power are thought to increase through normalization of the balance of the temporomandibular joint by hindering midline transition during the occurrence of a strong bite force in subjects with mild midline discrepancy, thanks to midline correction. This finding supports that of a previous study12) indicating that the arrangement of the neck and the jaw was closely related. "
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    ABSTRACT: [Purpose] This study was conducted to investigate the changes in torque and power during flexion and extension of the shoulder and the knee joints caused by midline correction using mouth guards made from different materials in adults with mild midline discrepancy. [Subjects] The subjects of this study were males (n=12) in their 20s who showed a 3-5 mm difference between the midlines of the upper and lower teeth but had normal masticatory function. [Methods] The torque and average power of the lower limb and upper limb were measured during flexion and extension according to various types of mouth guard. [Results] There were significant differences in relative torque and average power between three conditions (no mouth guard, soft-type mouth guard, and hard-type mouth guard) at shoulder flexion and extension. There were no significant differences in relative torque and average power between the three conditions at knee flexion and extension. [Conclusions] These results suggest that use of a mouth guard is a method by which people with a mild midline discrepancy can improve the stability of the entire body.
    Journal of Physical Therapy Science 07/2014; 26(7):1051-3. DOI:10.1589/jpts.26.1051 · 0.20 Impact Factor
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    • "No difference was noted between associated anomalies or specific types of malocclusions and signs and symptoms of TMD. Bakke suggests that even if much controversy has been reported regarding the role of occlusion in TMD, there is, however, no doubt that occlusal variables influence natural masticator muscle function [35]. This study reports a significant influence of overbite on signs of TMD. "
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    ABSTRACT: To establish the skeletal pattern in subjects with malocclusions and temporomandibular disorders (TMD); to assess the relationship between craniofacial skeletal structures and TMD in subjects with malocclusions. Sixty-four subjects with malocclusions, over 18 years of age, were included in the study. Temporomandibular disorders were clinically assessed according to the Helkimo Anamnestic Index. Subjects underwent a lateral cephalogram. Subjects were grouped according to the sagittal skeletal pattern (ANB angle) into class I, II and III. Parametric Student tests with equal or unequal variations were used (variations were previously tested with Levene test). Twenty-four patients with TMD (experimental sample); 40 patients without TMD (control group); interincisal angle was higher in class I and II (p < 0.05) experimental subjects; overjet was larger in experimental subjects; midline shift and Wits appraisal were broader in the experimental group in all three classes. In class III subjects, the SNB angle was higher in the experimental group (p = 0.01). Joint noises followed by reduced mandible mobility, muscular pain and temporomandibular joint (TMJ) pain were the most frequent symptoms in subjects with TMD and malocclusions. Temporomandibular joint status is an important factor to consider when planning orthodontic treatment in patients with severe malocclusions; midline shift, large overjet and deep overbite have been associated with signs and symptoms of TMD.
    Archives of Medical Science 02/2013; 9(1):118-26. DOI:10.5114/aoms.2013.33072 · 2.03 Impact Factor
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