A method for standardization of silent period measurements in human masseter muscle

Abstract

The effect of bite force and stimulus intensity on the electrically induced SP has been studied. The results from the present study and earlier investigations suggest that the following guidelines should be used in future SP studies. (i) The electrical rather than mechanical way of stimulation should be preferred since the stimulus parameters and the receptors stimulated can easily be determined. (ii) The sensory perception threshold (T) of subjects should be used when studying and comparing the SP between individuals rather than the actual values of the electrical stimulation since the value of the sensory perception threshold varies from subject to subject. (iii) Rectified and averaged EMG records should be used rather than single raw traces since it is not possible to measure the duration of SPs from single traces. (iv) The subject should be asked to perform 25% of his/her MBF and the BF should be given as a feedback. (v) A stimulus intensity of about 6T should be used so that small changes in the BF would not affect the SPD. (vi) A jaw separation of about 10 mm should be selected in the subjects with normal overjet (2-3 mm), this being slightly thicker than the average isometric force transducer. The transducer can be brought to this thickness using acrylic resin. (vii) A head rest should be used to keep the head position constant (and hence constant jaw position with respect to the transducer) since the head position alone may change the reflexes elicited in the jaws region.

Jaw elevator silent periods in complete denture wearers and dentate individuals

“…The latencies varied between 12.5 and 12.9 ms and were similar to the latencies elicited in other studies by a menton tap (Ciancaglini et al, 1989;Karkazis and Kossioni, 1999;Kossioni and Karkazis, 1995a,b, 1998, but were shorter than the latencies of SPs elicited by electrical stimulation of the tooth pulp (Sharav et al, 1982), the lower lip (20 ms) (Tü rker, 1988;Tü rker and Miles, 1985) or by mechanical stimulation of the hard palate (50 ms) (Di Francesco et al, 1986) and the skin over the masseter muscle (54 ms) (Yemm, 1972). Due to the short latency in DI group (Table 1), the reflex may be considered to be olygosynaptic.…”

“…Although some authors attribute SP eliciting mainly to periodontal receptors' stimulation and/or muscle unloading, it is possible that other receptors play a role in that process (Alajbeg et al, 2005;Bessette et al, 1971;Brenman et al, 1968;Brodin et al, 1991;Cadden and Newton, 1992;Chong-Shan and Hui-Yun, 1989;Ciancaglini et al, 1989;Dessem et al, 1988;Freesmeyer, 1987;Di Francesco et al, 1986;Griffin and Munro, 1971;Jacobs and van Steenberghe, 2006;Karkazis, 1998, 1999;De Laat et al, 1985;Lavigne et al, 1983;Schaerer et al, 1967;Tallgren et al, 1987;Tü rker andMiles, 1985, 1989;Tü rker et al, 1994;Tü rker and Jenkins, 2000;Yoshida, 1998;Widmalm and Hedegard, 1976;Widmalm and Ash, 1985;Yemm, 1972).…”

“…In masticatory elevator muscles SP commences after functional contacts of the opposing teeth or after some other stimulus applied to oral and perioral region during the muscle contraction (Graven-Nielsen et al, 2000;Griffin and Munro, 1969;Haraldson and Ingerwall, 1979;Hellsing and Klineberg, 1983;Hoffman, 1919;Jacobs and van Steenberghe, 1995;Sharav et al, 1982;van Steenberghe, 1979;Tü rker, 1988).…”

Internal Organization in the Human Jaw Muscles

“…Multiunit and single MU recordings have been made in many human studies and most often analyzed by averaging techniques (e.g., Cadden and Newton, 1989;Turker etal, 1989). The validity of multiunit electromyography as a method for measuring jaw reflex activity can be disputed (Lavigne etal, 1983;Turker, 1988). The relative position of the stimulus during repetitive MU activity, MU firing rate, and the task performed are all known to affect reflex inhibition in the human jaw muscles, and MU synchronization can be misinterpreted as an apparent excitatory response when averaging techniques are used (Widmer and Lund, 1989).…”

Reflex Control of Human Jaw Muscles

“…Usually, the sensory perception threshold (T) of the subject is used to standardize the stimulus intensity rather than the actual voltage or the current delivered (Türker, 1988). Intensities of 1-3 T are used to stimulate lowthreshold afferents which convey information about touch…”