Comparison of the Reproducibility of EMG Signals Recorded from Human Masseter and Lateral Pterygoid Muscles

Abstract

EMG recordings of the left and right masseter and lateral pterygoid muscles were repeated three times in 15 young adults to test the reproducibility of the signals. Two tests were made on the same day (morning and afternoon) and one test three days later (morning). Needle and hook electrodes were used for the masseter muscle and needle electrodes for the lateral pterygoid muscle. The superficial areas of recording were tattooed on the skin. An intra-oral approach was selected for the lateral pterygoid muscle. The subjects were asked to perform three definite tasks for the masseter muscle (intercuspid occlusion, maximum protrusion, and centric relation with a bite opening of 3mm) and two for the pterygoid muscle (maximum opening and maximum protrusion). The EMG signals were directly integrated, and root mean squares of the AC components were computed. The selection of the signals to discard possible artefacts was performed by displaying EMG and RMS outputs on a six-channel UV oscillograph. The selected RMS values were submitted to different analyses of variance to define additive and non-additive models of effects. The results may be summarized as follows: The between-day sessions showed more variation than the within-day sessions. The variations related to the method accounted for a very high percentage of the total variance (48.9%). The recordings with needle electrodes displayed a large percentage of the individual variation (masseter, 31.2%; lateral pterygoid muscle, 65.9%) and significantly lower values for the variations related to the session or the side of recording. The one-side recordings were more suitable for distinguishing the biological variations than were the bilateral ones. The right side was less sensitive to variations than the left side. The study of the lateral pterygoid muscle was less dependent on "session", "side", or "task" effects than was that of the masseter muscle. The lack of significant variation resulting from the performed tasks suggested that only the lower bundle was recorded with a similar activity in protrusion and opening. The reproducibility of the superficial recordings of the masseter muscle may be improved if non-significant interactions between "task" and "area" or "side" factors, as well as between "task" and "session", are taken into consideration. A direct comparison of the different tasks performed in one "session" will help reduce the undesirable effects due to the random selection of the recording "side" or "site".

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References

Ahlgren, J. ; Lewis, G.R. ; and Yemm, R. (1980): A Comparison in Man of the Performance of Two Types of Surface Electrode used for Electromyography, Arch Oral Biol 25:477-480.

Auf Der Maur, H.J. (1978): Elektromyographische Befunde am Musculus pterygoideus extemus während der Distalbisstherapie mit dem Aktivator, Schweiz Mschr Zahnheilk 88:1085-1099.

Auf Der Maur, H.J. (1980): Electromyographic Recordings of the Lateral Pterygoid Muscle in Activator Treatment of Cl II Div. 1 Malocclusion Cases, Europ J Orthod 2:161-171.

Barbenel, J.C. (1969): Analysis of Forces at the Temporo-mandibular Joint during Function, Dent Practit 19:305-310.

Chilton, N.W. (1967): Design and Analysis in Dental and Oral Research . Philadelphia: Lippincott Co. , pp. 75-115.

Colton, T. (1984): Statistics in Medicine. Boston : Little, Brown & Co., p. 138.

Currier, D.P. (1969): Measurement of Muscle Fatigue, Phys Ther 49:724-730.

Dahan, J. (1979): Temporalis und Massetereinwirkung in der Formveranderung des Unterkiefers, Fortschr Kieferorthop 40:392-407.

Eschler, J. (1951): Grundlagen und Ergebnisse über die Steigerung der Muskeltatigkeit bei eingezetztem Andresen- Haupl Apparat, Zahnaertztl Welt 6:187-195.

10.

Frame, J.W. ; Rothwell, P.S. ; and Duxbury, A.J. (1973): The Standardization of Electromyography of the Masseter Muscle in Man, Arch Oral Biol 18:1419-1423.

11.

Garnick, J.J. (1975): Reproducibility of the Electromyogram, J Dent Res 54:867-871.

12.

Gibbs, C.H. ; Mahan, P.E. ; Wilkinson, T.M. ; and Mauderli, A. (1984): E.M.G. Activity of the Superior Belly of the Lateral Pterygoid Muscle in Relation to other Jaw Muscles, J Prosthet Dent 51:691-702.

13.

Greenfield, B.E. and Wyke, B.D. (1956): Electromyographic Studies of Some of the Muscles of Mastication, Br Dent J 100: 129-143.

14.

Lehr, R.P. and Owens, S.E. (1980): An Electromyographic Study of the Human Lateral Pterygoid Muscle, Anat Rec 196:441-448.

15.

Luschei, E.S. and Goodwin, G.M. (1974): Patterns of Mandibular Movement and Jaw Muscle Activity during Mastication in Monkeys, J Neurophysiol 37:954-966.

16.

Mahan, P.E. ; Gibbs, C.H. ; and Mauderli, A. (1982): Superior and Inferior Lateral Pterygoid E.M.G. Activity, J Dent Res 61:272 (Abstr. No. 19).

17.

Mahan, P.E. and Wilkinson, T.M. (1983): Superior and Inferior Bellies of the Lateral Pterygoid Muscle E.M.G. Activity at Basic Jaw Positions, J Prosthet Dent 50:710-718.

18.

McNamara, J.A., Jr. (1973): The Independent Function of the Two Heads of the Lateral Pterygoid Muscle, Am J Anat 138:197-206.

19.

McNamara, J.A., Jr. (1980): Functional Determinants of Craniofacial Size and Shape, Europ J Orthod 2:131-159.

20.

McNamara, D.C. (1976): Electrodiagnosis at Median Occlusal Position for Human Subjects with Mandibular Joint Syndrome, Arch Oral Biol 21:325-328.

21.

Mller, E. (1966): The Chewing Apparatus, Acta Physiol Scand 69:Suppl 280.

22.

Moyers, R.E. (1950): An Electromyographic Analysis of Certain Muscles Involved in Temporo-mandibular Movement, Am J Orthod 7:481-515.

23.

Palla, S. and Ash, M. (1981): Effect of Bite Force in the Power Spectrum of the Surface Electromyogram of Human Muscles, Arch Oral Biol 26:287-295.

24.

Petrovic, A.G. and Oudet, C.L. (1978): Variations in the Number of Sarcomeres Produced by the Postural Hyperpropulsion. Monograph No. 8, Ann Arbor, MI: University of Michigan Center of Human Growth and Development, pp. 233-245.

25.

Petrovic, A.G. ; Stutzmann, J. ; and Oudet, C. (1975): Control Process in the Postnatal Growth of the Mandibular Condylar Cartilage. In: Determinants of Mandibular Form and Growth, Monograph 4, Craniofacial Growth Series. McNamara, J.A., Jr. , Ed., Ann Arbor : Center for Human Growth and Development, University of Michigan, pp. 101-153.

26.

SAS User's Guide 1982: Statistical Analysis System, T. Helwig and A. Council , Eds., Raleigh, NC: SAS Institute, pp. 117-143.

27.

Sessle, B.J. and Gurza, S.C. (1982): Jaw Movement-related Activity and Reflexly-induced Changes in the Lateral Pterygoid Muscle of the Monkey, Arch Oral Biol 27:167-173.

28.

Snedecor, G.W. and Cochran, W.G. (1980): Statistical Methods, 7th ed. Ames, Iowa: State University Press, pp. 291-328.

29.

Tallgren, A. ; Melsen, B. ; and Hansen, M. (1979): An Electromyographic and Roentgencephalometric Study of Occlusal Morphofunctional Dysharmony in Children, Am J Orthod 76 :394-409.

30.

Viitasalo, J.H. and Komi, P.V. (1977): Signal Characteristic of E.M.G. during Fatigue , Europ J Appl Physiol 37:111-121.

31.

Vitti, M. and Basmajian, J.V. (1976): Integrated Actions of Masticatory Muscles, Simultaneous E.M.G. from Eight Intra-muscular Electrodes, Anat Rec 187:173-189.

32.

Yemm, R. (1977a): The Representation of Motorunit Action Potentials on the Skin Surface Electromyograms of Masseter and Temporal Muscles, Arch Oral Biol 22:201-205.

33.

Yemm, R. (1977b): The Orderly Recruitment of Motor Units of the Masseter and Temporal Muscles during Voluntary Contraction in Man, J Physiol (Lond) 265:163-174.