Electromyographic-force Characteristics in the Assessment of Oral Function

Abstract

The purpose of this investigation was to examine the utility of EMG-force characteristics as reliable and valid parameters by which to assess oral function. Masseter-muscle activity was recorded during controlled isometric biting exercises performed at various bite openings and force levels on two separate occasions. Measured muscle-activity levels, as well as the EMG-force characteristics of slope and y-intercept, were compared between bite openings and experimental trials. Sensitivity, assessed as the ability to detect statistically significant differences in muscle function due to changes in muscle length, was found to be acceptable for all measurements, except the y-intercept parameter, and during production of minimal forces. Reproducibility, evaluated as the correspondence between values recorded at different experimental sessions, was best for the EMG-force parameter of slope and during production of higher forces. The results from this study support the following conclusions: (1) Substantial variations in muscle function exist between individuals; (2) acceptable reliability and sensitivity of quantitative EMG values can be achieved, especially at higher muscle-activity levels, by rigidly controlling and quantifying functional activities during experimental trials; (3) the slope of an EMG-force curve is a reproducible, quantitative, and functionally sensitive measurement for assessment of muscle function; and (4) the EMG-force y-intercept is not a reliable quantity by which muscle-function characteristics may be studied.

Recruitment stability in masseter motor units during isometric voluntary contractions

“…ings of the current study and some previous work. 11,18 The difference between the results in the current study and the findings of Mao and Osborn 20 may relate to the different methodologies used; a ramp force in the current study and incremental 50-N bite tasks in their study. Furthermore, neither van Eidjen et al 33 nor Mao and Osborn 20 investigated the first 50 N of bite force; the current study showed that many of the masseter SMUs were recruited in this part of the contraction.…”

Site-to-site variation of muscle activity and sensitivity in the human anterior temporalis muscle: Implications for contingent stimulation

“…A previous study has shown large variability of EMG activity exhibited between subjects although they performed identical tasks [24]. In the present study, there was a marginal difference of EMG activity within the same site during an identical task.…”

Regulation of Mandibular Postures: Mechanisms and Clinical Implications

“…This proposal has been rejected by several recent studies that have examined the relationship between maximal biting force and experimental variations in OVD. As the OVD is increased from a position of infra-gnathism (Morimoto et al, 1996) to a position 15 to 20 mm greater than the free-way space norm, the maximal biting force also increases (Boucher et al, 1959;Manns et al, 1979;Mackenna and Turker, 1983;Fields et al, 1986;Lindauer et al, 1991;Prombonas et al, 1994) (Fig. ).…”