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Moreira LS, Elias LA, Germer CM, Palomari ET. Reliable measurement of incisal bite force for understanding the control of masticatory muscles. Arch Oral Biol 2020; 112:104683. [PMID: 32120053 DOI: 10.1016/j.archoralbio.2020.104683] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 01/12/2020] [Accepted: 02/17/2020] [Indexed: 11/16/2022]
Abstract
OBJECTIVE In the present study, we aimed at evaluating the steadiness of incisal bite force during isometric contractions of masticatory muscles. DESIGN Two separate experiments were carried out in 11 healthy young women. A first experiment was performed to test the reliability of our protocol for measurement of incisal bite force steadiness. The second experiment aimed to evaluate the steadiness of incisal bite force at four submaximal (i.e., percentage of maximum voluntary contraction, MVC) levels (5 %MVC, 10 %MVC, 15 %MVC, and 20 %MVC), along with the bilateral myoelectric activity of two masticatory muscles (temporalis and masseter). RESULTS The results from the first experiment showed that our protocol is substantially reliable (intraclass correlation coefficient, ICC > 0.80) for estimating force variability and moderate reliable (0.60 < ICC < 0.80) for estimating spectral properties of force signals. In the second experiment, we found that force standard deviation (SD) increased proportionally to the power of mean force, and coefficient of variation (CoV) was higher at low-intensity contractions and maintained at an approximately constant level for high-intensity contractions. The force-EMG relationships were linear for both muscles at the contraction intensities evaluated in the study (5 %MVC to 20 %MVC), and the median frequency did not change with contraction intensity. CONCLUSION Therefore, we presented a reliable method to estimate the incisal bite force, along with additional data on force control and myoelectric activity of jaw elevator muscles during isometric steady contractions.
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Affiliation(s)
- Luciana S Moreira
- Cellular and Structural Biology Graduate Program, Institute of Biology, University of Campinas, Campinas, SP, Brazil; EMG, Motor Control, and Experimental Electrothermotherapy Laboratory, Department of Structural and Functional Biology, Institute of Biology, University of Campinas, Campinas, SP, Brazil; Neural Engineering Research Laboratory, Department of Biomedical Engineering, School of Electrical and Computer Engineering, University of Campinas, Campinas, SP, Brazil.
| | - Leonardo A Elias
- Neural Engineering Research Laboratory, Department of Biomedical Engineering, School of Electrical and Computer Engineering, University of Campinas, Campinas, SP, Brazil; Center for Biomedical Engineering, University of Campinas, Campinas, SP, Brazil
| | - Carina M Germer
- Neural Engineering Research Laboratory, Department of Biomedical Engineering, School of Electrical and Computer Engineering, University of Campinas, Campinas, SP, Brazil
| | - Evanisi T Palomari
- Cellular and Structural Biology Graduate Program, Institute of Biology, University of Campinas, Campinas, SP, Brazil; EMG, Motor Control, and Experimental Electrothermotherapy Laboratory, Department of Structural and Functional Biology, Institute of Biology, University of Campinas, Campinas, SP, Brazil
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Testa M, Di Marco A, Pertusio R, Van Roy P, Cattrysse E, Roatta S. A validation study of a new instrument for low cost bite force measurement. J Electromyogr Kinesiol 2016; 30:243-8. [DOI: 10.1016/j.jelekin.2016.08.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2016] [Revised: 08/01/2016] [Accepted: 08/08/2016] [Indexed: 11/30/2022] Open
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Uginčius P, Atiş ES, Türker KS. Reflex responses of human masseter motor units to mechanical stimulation of the teeth. J Neurophysiol 2013; 111:51-61. [PMID: 24133225 DOI: 10.1152/jn.00478.2013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Our aim was to investigate the jaw reflexes using both the probability- and the discharge rate-based analysis methods. Twelve consenting volunteer subjects participated in this study. Subjects bit gently on bite bars that carried the impression of their teeth. Surface and intramuscular electrical activity of the masseter was recorded. With the help of audio feedback from one motor unit, each subject bit to discharge the unit at a fixed rate. While the subject continuously activated the selected motor unit, 4-N stimuli were delivered to the upper right central incisor either at a rapid or a slow rate. For each trial, ≥300 stimuli were delivered, and, once a trial was completed, local anesthetic block was applied around the stimulated tooth, and the experiment was repeated. While preceding local anesthesia, the rapid-rate stimuli ("tap") induced substantial inhibitory reflex responses; during local anesthetic block, the same stimulus induced excitatory and inhibitory reflex responses. Slow-rate stimuli ("push"), on the other hand, usually generated a combination of inhibitory and excitatory responses that disappeared completely during the local anesthetic block. This study discovered that the strength of the inhibitory reflex response to a tooth-tap stimulus was much larger than previously reported. This study also found that whereas the probability-based analyses were better for illustrating the existence and latency of small earlier responses, the discharge rate-based method was better for indicating the duration of earlier responses and the existence, sign, and duration of later responses.
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Affiliation(s)
- P Uginčius
- Institute of Physiology and Pharmacology, Medical Academy, Lithuanian University of Health Sciences, Kaunas, Lithuania
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D'Amico JM, Yavuz ŞU, Saraçoglu A, Atiş ES, Gorassini MA, Türker KS. Activation properties of trigeminal motoneurons in participants with and without bruxism. J Neurophysiol 2013; 110:2863-72. [PMID: 24068753 DOI: 10.1152/jn.00536.2013] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
In animals, sodium- and calcium-mediated persistent inward currents (PICs), which produce long-lasting periods of depolarization under conditions of low synaptic drive, can be activated in trigeminal motoneurons following the application of the monoamine serotonin. Here we examined if PICs are activated in human trigeminal motoneurons during voluntary contractions and under physiological levels of monoaminergic drive (e.g., serotonin and norepinephrine) using a paired motor unit analysis technique. We also examined if PICs activated during voluntary contractions are larger in participants who demonstrate involuntary chewing during sleep (bruxism), which is accompanied by periods of high monoaminergic drive. In control participants, during a slowly increasing and then decreasing isometric contraction, the firing rate of an earlier-recruited masseter motor unit, which served as a measure of synaptic input to a later-recruited test unit, was consistently lower during derecruitment of the test unit compared with at recruitment (ΔF = 4.6 ± 1.5 imp/s). The ΔF, therefore, is a measure of the reduction in synaptic input needed to counteract the depolarization from the PIC to provide an indirect estimate of PIC amplitude. The range of ΔF values measured in the bruxer participants during similar voluntary contractions was the same as in controls, suggesting that abnormally high levels of monoaminergic drive are not continually present in the absence of involuntary motor activity. We also observed a consistent "onion skin effect" during the moderately sized contractions (<20% of maximal), whereby the firing rate of higher threshold motor units discharged at slower rates (by 4-7 imp/s) compared with motor units with relatively lower thresholds. The presence of lower firing rates in the more fatigue-prone, higher threshold trigeminal motoneurons, in addition to the activation of PICs, likely facilitates the activation of the masseter muscle during motor activities such as eating, nonnutritive chewing, clenching, and yawning.
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Affiliation(s)
- Jessica M D'Amico
- Department of Biomedical Engineering, Centre for Neuroscience, University of Alberta, Canada
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Naser-Ud-Din S, Sowman PF, Sampson WJ, Dreyer CW, Türker KS. Masseter length determines muscle spindle reflex excitability during jaw-closing movements. Am J Orthod Dentofacial Orthop 2011; 139:e305-13. [PMID: 21457836 DOI: 10.1016/j.ajodo.2009.12.033] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2009] [Revised: 12/01/2009] [Accepted: 12/01/2009] [Indexed: 10/18/2022]
Abstract
INTRODUCTION The masticatory muscles are considered to be important determinants of facial form, but little is known of the muscle spindle reflex characteristics and their relationship, if any, to face height. The aim of this study was to determine whether spindle reflexes, evoked by mechanical stimulation of an incisor and recorded on the masseter muscle, correlated with different facial patterns. METHODS Twenty-eight adult volunteers (16 women; ages, 19-38 years) underwent 2-N tap stimuli to their maxillary left central incisor during simulated mastication. Reflexes were recorded during local anesthesia of the stimulated tooth to eliminate the contribution from periodontal mechanoreceptors. Surface electromyograms of the reflex responses of the jaw muscles to these taps were recorded via bipolar electrodes on the masseter muscle and interpreted by using spike-triggered averaging of the surface electromyograms. Lateral cephalometric analysis was carried out with software (version 10.5, Dolphin, Los Angeles, Calif; and Mona Lisa, Canberra, Australia). RESULTS Two-newton tooth taps produced principally excitatory reflex responses beginning at 17 ms poststimulus. Correlation analysis showed a significant relationship between these muscle spindle reflexes and facial heights: specifically, shorter face heights were associated with stronger spindle reflexes. This correlation was strongest between the derived measure of masseter length and the spindle reflex strength during jaw closure (r = -0.49, P = 0.008). CONCLUSIONS These results suggest that a similar muscle spindle stimulus will generate a stronger reflex activation in the jaw muscles of patients with shorter faces compared with those with longer faces. This finding might help to explain the higher incidence of clenching or bruxism in those with short faces and also might, in the future, influence the design of orthodontic appliances and dental prostheses.
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Naser-ud-Din S, Sowman P, Dang H, Türker K. Modulation of Masseteric Reflexes by Simulated Mastication. J Dent Res 2009; 89:61-5. [DOI: 10.1177/0022034509352842] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
It is well-known that limb muscle reflexes are modulated during human movements. However, little is known about the existence of equivalent masticatory muscle reflex modulation. We hypothesized that masticatory reflexes would be modulated during chewing so that smooth masticatory movements occur. To examine this hypothesis, we studied the modulation of inhibitory reflexes evoked by periodontal mechanoreceptor activation and of excitatory reflexes evoked by muscle spindle activation during simulated mastication. In 28 participants, 1- and 2-N mechanical taps were delivered to the incisor. Reflex responses to these taps were examined in the average masseteric electromyogram. To differentiate between periodontal mechanoreceptor- and muscle-spindle-mediated reflex components, we performed experiments prior to, and in the presence of, periodontal anesthesia. Both periodontal mechanoreceptor and muscle spindle reflexes were reduced during simulated masticatory movements.
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Affiliation(s)
- S. Naser-ud-Din
- Discipline of Physiology & Research Centre for Human Movement Control, School of Molecular and Biomedical Science, University of Adelaide, Australia
- School of Dentistry, University of Adelaide, Australia
- Department of Orthodontics, University of Adelaide, Australia
- Macquarie Centre for Cognitive Science (MACCS), Macquarie University, Sydney, Australia; and
- Center for Brain Research, Department of Physiology, Faculty of Medicine, Ege University, Bornova, Izmir, Turkey
| | - P.F. Sowman
- Discipline of Physiology & Research Centre for Human Movement Control, School of Molecular and Biomedical Science, University of Adelaide, Australia
- School of Dentistry, University of Adelaide, Australia
- Department of Orthodontics, University of Adelaide, Australia
- Macquarie Centre for Cognitive Science (MACCS), Macquarie University, Sydney, Australia; and
- Center for Brain Research, Department of Physiology, Faculty of Medicine, Ege University, Bornova, Izmir, Turkey
| | - H. Dang
- Discipline of Physiology & Research Centre for Human Movement Control, School of Molecular and Biomedical Science, University of Adelaide, Australia
- School of Dentistry, University of Adelaide, Australia
- Department of Orthodontics, University of Adelaide, Australia
- Macquarie Centre for Cognitive Science (MACCS), Macquarie University, Sydney, Australia; and
- Center for Brain Research, Department of Physiology, Faculty of Medicine, Ege University, Bornova, Izmir, Turkey
| | - K.S. Türker
- Discipline of Physiology & Research Centre for Human Movement Control, School of Molecular and Biomedical Science, University of Adelaide, Australia
- School of Dentistry, University of Adelaide, Australia
- Department of Orthodontics, University of Adelaide, Australia
- Macquarie Centre for Cognitive Science (MACCS), Macquarie University, Sydney, Australia; and
- Center for Brain Research, Department of Physiology, Faculty of Medicine, Ege University, Bornova, Izmir, Turkey
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Modulation of human exteroceptive jaw reflexes during simulated mastication. Clin Neurophysiol 2009; 120:398-406. [DOI: 10.1016/j.clinph.2008.11.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2008] [Revised: 10/23/2008] [Accepted: 11/12/2008] [Indexed: 11/23/2022]
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Türker KS, Sowman PF, Tuncer M, Tucker KJ, Brinkworth RSA. The role of periodontal mechanoreceptors in mastication. Arch Oral Biol 2007; 52:361-4. [PMID: 17222796 DOI: 10.1016/j.archoralbio.2006.11.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2006] [Revised: 11/23/2006] [Accepted: 11/23/2006] [Indexed: 10/23/2022]
Abstract
The aim of this review is to discuss what is known about the reflex control of the human masticatory system by the periodontal mechanoreceptors and to put forward a method for standardised investigation. To deliver mechanical stimulus in a reproducible way, the following precautions are suggested: the stimulus should be brought into secure contact with the area of stimulation, and slack between the probe and the area to be stimulated should be taken up by the application of a preload. It is also important to ensure that there is minimal simultaneous activation of receptor systems other than the periodontal mechanoreceptors. It is also necessary to standardise the method for recording and analysing the response.
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Affiliation(s)
- Kemal S Türker
- Research Centre for Human Movement Control, University of Adelaide, SA 5005, Australia.
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Brinkworth RSA, Türker KS. Jaw movement alters the reaction of human jaw muscles to incisor stimulation. Exp Brain Res 2005; 164:165-76. [PMID: 15868176 DOI: 10.1007/s00221-005-2239-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2004] [Accepted: 11/11/2004] [Indexed: 10/25/2022]
Abstract
The changes in the minimum time to consciously react (reaction time) and the order of jaw muscle recruitment to precisely controlled axial stimulation of the incisors during controlled jaw movements are not known. To this end, ten subjects were recruited to investigate the reaction time of bilateral temporalis and masseter muscles and bite force. Stimuli were delivered axially to the upper central incisors during active jaw closing and opening, and under static conditions. The results showed that the reaction time was increased an average of 35% during both jaw opening and closing movements when compared with static jaw conditions. The left temporalis was recruited approximately 10 ms before the right temporalis, whereas no significant side differences were found between the masseter muscles. The masseter muscles were recruited an average of 20 ms before the temporalis muscles during jaw closing, but no difference existed during opening. Under static conditions the reaction time in the bite force was approximately 16 ms longer than the left temporalis, but was not significantly different from the reaction time of any of the other muscles, indicating that, under the static conditions tested, the left temporalis was more often responsible for initiation of the mechanical reactions in the jaw. Because of active compensation, no force measurements were made during jaw movement. This study is a prerequisite for investigations into the modulation of reflexes during jaw movement, because a response to a stimulus commencing after the minimum reaction time may not be entirely reflex in origin.
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Affiliation(s)
- Russell S A Brinkworth
- Research Centre for Human Movement Control, Discipline of Physiology, School of Molecular and Biomedical Science, The University of Adelaide, Adelaide, SA, 5005, Australia
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Brinkworth RSA, Male C, Türker KS. Response of human jaw muscles to axial stimulation of a molar tooth. Exp Brain Res 2004; 159:214-24. [PMID: 15241573 DOI: 10.1007/s00221-004-1949-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2003] [Accepted: 04/08/2004] [Indexed: 11/28/2022]
Abstract
The reflexes of the main jaw-closer muscles (masseter and anterior temporalis) on both sides of the jaw were investigated using surface electromyography to observe reflex activity following mechanical stimulation of the 1st right upper-molar tooth at various forces under a number of levels of jaw-muscle activity. As with analogous studies performed on the incisor, three distinct reflex events were identified in the EMG before the earliest conscious subject reaction: early excitation, inhibition and late excitation. However, contrary to observations found during studies on the incisor, excitation, not inhibition was the primary reflex response. The application of a local anaesthetic block around the stimulated molar showed that the primary agents in eliciting the observed reflexes were not contained within the periodontium of the stimulated tooth. A diminished representation of periodontal mechanoreceptors around the molar teeth and more elaborate root structures, hence a more solid connection to the jaw and consequently less tooth movement, were deemed the likely reason for the distinction between the reflex responses of the incisal and molar regions. In addition to the reflex studies, the minimum reaction time of a number of subjects was determined to permit the distinction of a reflex event and an event that could be a conscious subject reaction. It was found that the reaction time of the temporalis muscles was significantly shorter than those of the masseter, while no significant difference was found between the left and right sides. Overall, the data showed that the presence or absence of background muscle activity and subject variability were the main causes of changes in the reflex response, provided the level of the stimulus was greater than 3 N. The application of local anaesthetic had no impact on the reflexes evoked.
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Affiliation(s)
- Russell S A Brinkworth
- Research Centre for Human Movement Control, Discipline of Physiology, School of Molecular and Biomedical Sciences, University of Adelaide, SA 5005, Australia
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