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Vassandacoumara V, Gheorghe TI, Leekam R, Lam EWN, Perschbacher SE, Liebgott B, Agur AMR. Musculoaponeurotic architecture of the human masseter muscle: an in vivo ultrasonographic study of architectural changes during mandibular protrusion and lateral excursions. Oral Surg Oral Med Oral Pathol Oral Radiol 2024:S2212-4403(24)00060-9. [PMID: 38490930 DOI: 10.1016/j.oooo.2024.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Revised: 01/17/2024] [Accepted: 02/07/2024] [Indexed: 03/17/2024]
Abstract
OBJECTIVE The present study evaluated the in vivo musculoaponeurotic architecture of the superficial head (SH) of the masseter muscle (MM) of asymptomatic participants in excursive mandibular movements compared to the relaxed state as examined with ultrasonography. It was hypothesized that the mean fiber bundle length (FBL) and mean height of the aponeurosis (HA) of the laminae of the SH would differ significantly between the relaxed state and protrusion, ipsilateral excursion, and contralateral excursion. STUDY DESIGN The MM was studied volumetrically in 12 female and 12 male asymptomatic participants bilaterally by using ultrasound imaging. Mean FBL and HA in protrusion and ipsilateral and contralateral excursion were compared to these values in the relaxed state using paired t tests (P < .05). The intraclass correlation coefficient was used to assess intraexaminer reliability. RESULTS The SH exhibited multiple laminae. Fiber bundles were found to attach to bone and the superior and inferior aponeuroses. Mean FBL was significantly shorter and mean HA significantly longer in protrusion and the excursions than in the relaxed state although the pattern of altered laminae and aponeuroses differed among the mandibular movements. Intraexaminer reliability was excellent. CONCLUSION Specific changes in mean FBL and mean HA suggest differential contraction of the SH of the MM based on laminar morphology. These findings provide a baseline to investigate musculoaponeurotic changes in patients with myogenic masseter muscle pain.
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Affiliation(s)
- Vaishnavee Vassandacoumara
- Oral and Maxillofacial Radiology Graduate Program, Faculty of Dentistry, University of Toronto, Toronto, ON
| | - Teodora-Iunia Gheorghe
- Department of Surgery, Division of Anatomy, Faculty of Medicine, University of Toronto, Toronto, ON; Oral and Maxillofacial Radiology Graduate Program, Faculty of Dentistry, University of Toronto, Toronto, ON.
| | - Roger Leekam
- Department of Surgery, Division of Anatomy, Faculty of Medicine, University of Toronto, Toronto, ON
| | - Ernest W N Lam
- Oral and Maxillofacial Radiology Graduate Program, Faculty of Dentistry, University of Toronto, Toronto, ON; Graduate Department of Dentistry, Faculty of Dentistry, University of Toronto, Toronto, ON
| | - Susanne E Perschbacher
- Oral and Maxillofacial Radiology Graduate Program, Faculty of Dentistry, University of Toronto, Toronto, ON; Graduate Department of Dentistry, Faculty of Dentistry, University of Toronto, Toronto, ON
| | - Bernard Liebgott
- Department of Surgery, Division of Anatomy, Faculty of Medicine, University of Toronto, Toronto, ON; Graduate Department of Dentistry, Faculty of Dentistry, University of Toronto, Toronto, ON
| | - Anne Maria Reet Agur
- Department of Surgery, Division of Anatomy, Faculty of Medicine, University of Toronto, Toronto, ON; Graduate Department of Dentistry, Faculty of Dentistry, University of Toronto, Toronto, ON
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Saini H, Klotz T, Röhrle O. Modelling motor units in 3D: influence on muscle contraction and joint force via a proof of concept simulation. Biomech Model Mechanobiol 2022; 22:593-610. [PMID: 36572787 PMCID: PMC10097764 DOI: 10.1007/s10237-022-01666-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 12/02/2022] [Indexed: 12/28/2022]
Abstract
AbstractFunctional heterogeneity is a skeletal muscle’s ability to generate diverse force vectors through localised motor unit (MU) recruitment. Existing 3D macroscopic continuum-mechanical finite element (FE) muscle models neglect MU anatomy and recruit muscle volume simultaneously, making them unsuitable for studying functional heterogeneity. Here, we develop a method to incorporate MU anatomy and information in 3D models. Virtual fibres in the muscle are grouped into MUs via a novel “virtual innervation” technique, which can control the units’ size, shape, position, and overlap. The discrete MU anatomy is then mapped to the FE mesh via statistical averaging, resulting in a volumetric MU distribution. Mesh dependency is investigated using a 2D idealised model and revealed that the amount of MU overlap is inversely proportional to mesh dependency. Simultaneous recruitment of a MU’s volume implies that action potentials (AP) propagate instantaneously. A 3D idealised model is used to verify this assumption, revealing that neglecting AP propagation results in a slightly less-steady force, advanced in time by approximately 20 ms, at the tendons. Lastly, the method is applied to a 3D, anatomically realistic model of the masticatory system to demonstrate the functional heterogeneity of masseter muscles in producing bite force. We found that the MU anatomy significantly affected bite force direction compared to bite force magnitude. MU position was much more efficacious in bringing about bite force changes than MU overlap. These results highlight the relevance of MU anatomy to muscle function and joint force, particularly for muscles with complex neuromuscular architecture.
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Affiliation(s)
- Harnoor Saini
- Institute of Modelling and Simulation of Biomechanical Systems, University of Stuttgart, Pfaffenwaldring 5a, 70569 Stuttgart, BW Germany
| | - Thomas Klotz
- Institute of Modelling and Simulation of Biomechanical Systems, University of Stuttgart, Pfaffenwaldring 5a, 70569 Stuttgart, BW Germany
| | - Oliver Röhrle
- Institute of Modelling and Simulation of Biomechanical Systems, University of Stuttgart, Pfaffenwaldring 5a, 70569 Stuttgart, BW Germany
- Stuttgart Center for Simulation Technology (SC SimTech), University of Stuttgart, Pfaffenwaldring 5a, 70569 Stuttgart, BW Germany
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Siu WS, Shih YF, Lee SY, Hsu CY, Wei MJ, Wang TJ, Lin HC, Lin YL. Alterations in kinematics of temporomandibular joint associated with chronic neck pain. J Oral Rehabil 2022; 49:860-871. [PMID: 35699317 DOI: 10.1111/joor.13347] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Revised: 05/26/2022] [Accepted: 06/02/2022] [Indexed: 12/13/2022]
Abstract
BACKGROUND Temporomandibular disorder (TMD) is an umbrella term for pain and dysfunction of the temporomandibular joint (TMJ) and its associated structures. Patients with TMD show changes in TMJ kinematics and masticatory muscle activation. TMD is commonly comorbid with non-specific chronic neck pain (NCNP), which may be one of the risk factors for TMD. OBJECTIVES This study aimed to investigate whether patients with NCNP have altered TMJ kinematics and masticatory muscle activity. METHODS This was a cross-sectional exploratory study including 19 healthy participants and 20 patients with NCNP but without TMD symptoms. TMJ kinematics was measured during mouth opening and closing, jaw protrusion and jaw lateral deviation. Surface electromyography was used to record the muscle activity of the anterior temporalis, masseter, sternocleidomastoid and upper trapezius while clenching. Furthermore, cervical posture, cervical range of motion (ROM) and pressure-pain threshold of the neck and masticatory muscles were measured. RESULTS Compared with the healthy group, the NCNP group showed significantly reduced upper cervical rotation ROM (p = .041) and increased condylar path length (p = .02), condylar translation (opening p = .034, closing p = .011) and mechanical pain sensitivity of the upper trapezius (p = .018). Increased condylar translation was significantly correlated with reduced upper cervical mobility and poor cervical posture (r = -0.322 to -0.397; p = .012-.046). CONCLUSION Increased condylar translation and path length in patients with NCNP may indicate poor control of TMJ articular movement, which may result from neck pain or may be a compensation for limited neck mobility. Evaluation of excessive TMJ translation may be considered in patients with NCNP.
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Affiliation(s)
- Weng-Sam Siu
- Department of Physical Therapy and Assistive Technology, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Yi-Fen Shih
- Department of Physical Therapy and Assistive Technology, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Shyh-Yuan Lee
- Department of Dentistry, National Yang Ming Chiao Tung University, Taiwan.,Department of Stomatology, Taipei Veterans General Hospital, Taipei, Taiwan.,Department of Dentistry, Taipei City Hospital, Taipei, Taiwan
| | - Chih-Yu Hsu
- Department of Dentistry, National Yang Ming Chiao Tung University, Taiwan.,Department of Stomatology, Taipei Veterans General Hospital, Taipei, Taiwan
| | - Min-Ju Wei
- Department of Physical Medicine and Rehabilitation, Cheng Hsin General Hospital, Taipei, Taiwan
| | - Tzyy-Jiuan Wang
- Department of Physical Therapy and Assistive Technology, National Yang Ming Chiao Tung University, Taipei, Taiwan
| | - Hsiu-Chen Lin
- Department of Physical Therapy and Graduate Institute of Rehabilitation Science, China Medical University, Taichung, Taiwan
| | - Yin-Liang Lin
- Department of Physical Therapy and Assistive Technology, National Yang Ming Chiao Tung University, Taipei, Taiwan
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Nozad Mojaver Y, Tawadros P, Moura Ferreira P, Whittle T, Murray GM. Threshold variations of medial pterygoid single motor units during vertical or horizontal force tasks. J Oral Rehabil 2021; 48:1314-1326. [PMID: 34510487 DOI: 10.1111/joor.13257] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 08/19/2021] [Accepted: 09/01/2021] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To test the hypotheses that (a) the force thresholds at onset of medial pterygoid muscle single motor unit (SMU) activity do not decrease with an increase in the rate of force generation in standardised vertical or horizontal jaw-force tasks, and (b) there is evidence for functional heterogeneity within the medial pterygoid muscle. METHODS In 14 healthy participants, electromyographic recordings of the right medial pterygoid muscle were performed with intramuscular fine-wire electrodes during four isometric force tasks: vertical, horizontal contralateral, horizontal protrusion and horizontal ipsilateral, performed at two rates of force development (slow ramp, fast ramp). Computer tomography scans confirmed electrode location within the muscle, which was divided into medial and lateral parts. Force thresholds of onset of discriminated SMUs were compared between rates in each task; significance accepted at p < 0.05. RESULTS Of 45 SMU force thresholds studied in one or more tasks, there was no significant difference between slow and fast ramp within each force task, except slow ramp thresholds from the lateral part during the vertical force task were significantly higher than fast ramp thresholds. Reversals of recruitment order between tasks provided evidence for functional heterogeneity within the muscle. Force thresholds of the vertical tasks (range: 1-292.6 N) were mostly higher than for the horizontal tasks (range: 0.1-12.5 N). CONCLUSION The data are consistent with the proposal that the medial pterygoid muscle stabilises the jaw in the vertical plane during isometric force generation in the jaw closing, as well as horizontal directions.
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Affiliation(s)
- Yalda Nozad Mojaver
- Faculty of Medicine and Health, Sydney Dental School, Westmead Hospital Centre for Oral Health, The University of Sydney, Westmead, Australia
| | - Paul Tawadros
- Faculty of Medicine and Health, Sydney Dental School, Westmead Hospital Centre for Oral Health, The University of Sydney, Westmead, Australia
| | - Polyana Moura Ferreira
- Faculty of Medicine and Health, Sydney Dental School, Westmead Hospital Centre for Oral Health, The University of Sydney, Westmead, Australia
| | - Terry Whittle
- Faculty of Medicine and Health, Sydney Dental School, Westmead Hospital Centre for Oral Health, The University of Sydney, Westmead, Australia
| | - Greg M Murray
- Faculty of Medicine and Health, Sydney Dental School, Westmead Hospital Centre for Oral Health, The University of Sydney, Westmead, Australia
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Lapatki BG, Eiglsperger U, Schindler HJ, Radeke J, Holobar A, van Dijk JP. Three-dimensional amplitude characteristics of masseter motor units and representativeness of extracted motor unit samples. Clin Neurophysiol 2019; 130:388-395. [DOI: 10.1016/j.clinph.2018.12.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2018] [Revised: 11/06/2018] [Accepted: 12/09/2018] [Indexed: 12/22/2022]
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Yamaguchi S, Okada C, Watanabe Y, Watanabe M, Hattori Y. Analysis of masticatory muscle coordination during unilateral single-tooth clenching using muscle functional magnetic resonance imaging. J Oral Rehabil 2017; 45:9-16. [PMID: 29090477 DOI: 10.1111/joor.12583] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/26/2017] [Indexed: 12/15/2022]
Abstract
In a previous study, we used muscle functional magnetic resonance imaging to show that the anterior movement of the occlusal point increased the activity of the superior head of the ipsilateral lateral pterygoid muscle (ipsilateral SHLP) during unilateral single-tooth clenching. The purpose of this study was to verify the hypothesis that the increased activity of the ipsilateral SHLP described above serves to antagonise the occlusal force acting on the condyle. In total, 9 healthy volunteers were requested to perform left unilateral clenching at the first molar or first premolar region for 1 minute at 20% or 40% maximum voluntary clenching force. Changes in the mean proton transverse relaxation time (∆T2) were examined from the magnetic resonance images obtained before and after each clenching act as an index of the activity in all masticatory muscles. Correlation analyses of the mean ΔT2 for each volume of interest were performed with the first molar or premolar clenches to analyse the correlation between the activities in each muscle. A statistically significant correlation was exhibited between the ipsilateral temporal and ipsilateral SHLP (r = .651, P = .003) during first premolar clenching. However, no significant correlations were observed in the ipsilateral SHLP during first molar clenching. The results of this study suggest that the ipsilateral SHLP may contribute to the pulling of the mandibular condyle forward against the occlusal force generated by the ipsilateral temporal muscle.
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Affiliation(s)
- S Yamaguchi
- Division of Aging and Geriatric Dentistry, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - C Okada
- Division of Aging and Geriatric Dentistry, Tohoku University Graduate School of Dentistry, Sendai, Japan
| | - Y Watanabe
- Department of Health Services Management, Faculty of Health Sciences, Tohoku Fukushi University, Sendai, Japan.,Kansei Fukushi Research Center, Tohoku Fukushi University, Sendai, Japan
| | - M Watanabe
- Division of Aging and Geriatric Dentistry, Tohoku University Graduate School of Dentistry, Sendai, Japan.,Kansei Fukushi Research Center, Tohoku Fukushi University, Sendai, Japan
| | - Y Hattori
- Division of Aging and Geriatric Dentistry, Tohoku University Graduate School of Dentistry, Sendai, Japan
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Chen H, Whittle T, Gal JA, Murray GM, Klineberg IJ. The medial pterygoid muscle: a stabiliser of horizontal jaw movement. J Oral Rehabil 2017; 44:779-790. [PMID: 28664577 DOI: 10.1111/joor.12542] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/25/2017] [Indexed: 11/30/2022]
Abstract
There is limited information of the normal function of the human medial pterygoid muscle (MPt). The aims were to determine whether (i) the MPt is active throughout horizontal jaw movements with the teeth apart and (ii) whether single motor units (SMUs) are active during horizontal and opening-closing jaw movements. Intramuscular electrodes were placed in the right MPt of 18 participants who performed five teeth-apart tasks: (i) postural position, (ii) ipsilateral (i.e. right) jaw movement, (iii) contralateral movement, (iv) protrusive movement and (v) opening-closing movement. Movement tasks were guided by a target and were divided into BEFORE, OUT, HOLDING, RETURN and AFTER phases according to the movement trajectories recorded by a jaw tracking system. Increased EMG activity was consistently found in the OUT, HOLDING and RETURN phases of the contralateral and protrusive movement tasks. An increased RETURN phase activity in the ipsilateral task indicates an important role for the MPt in the contralateral force vector. Of the 14 SMUs active in the opening-closing task, 64% were also active in at least one horizontal task. There were tonically active SMUs at the postural jaw position in 44% of participants. These new data point to an important role for the MPt in the fine control of low forces as required for stabilisation of vertical mandibular position not only to maintain postural position, but also throughout horizontal jaw movements with the teeth apart. These findings provide baseline information for future investigations of the possible role of this muscle in oro-facial pain conditions.
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Affiliation(s)
- H Chen
- Jaw Function and Orofacial Pain Research Unit, Faculty of Dentistry, Westmead Hospital Centre for Oral Health, University of Sydney, Westmead, NSW, Australia
| | - T Whittle
- Jaw Function and Orofacial Pain Research Unit, Faculty of Dentistry, Westmead Hospital Centre for Oral Health, University of Sydney, Westmead, NSW, Australia
| | - J A Gal
- Jaw Function and Orofacial Pain Research Unit, Faculty of Dentistry, Westmead Hospital Centre for Oral Health, University of Sydney, Westmead, NSW, Australia
| | - G M Murray
- Jaw Function and Orofacial Pain Research Unit, Faculty of Dentistry, Westmead Hospital Centre for Oral Health, University of Sydney, Westmead, NSW, Australia
| | - I J Klineberg
- Jaw Function and Orofacial Pain Research Unit, Faculty of Dentistry, Westmead Hospital Centre for Oral Health, University of Sydney, Westmead, NSW, Australia
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Schindler HJ, Rues S, Türp JC, Schweizerhof K, Lenz J. Jaw Clenching: Muscle and Joint Forces, Optimization Strategies. J Dent Res 2016; 86:843-7. [PMID: 17720852 DOI: 10.1177/154405910708600907] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Realistic masticatory muscle and temporomandibular joint forces generated during bilateral jaw clenching are largely unknown. To determine which clenching directions load masticatory muscles and temporomandibular joints most heavily, we investigated muscle and joint forces based on feedback-controlled electromyograms of all jaw muscles, lines of action, geometrical data from the skull, and physiological cross-sectional areas acquired from the same individuals. To identify possible motor control strategies, we applied objective functions. The medial pterygoid turned out to be the most heavily loaded muscle for all bite directions. Biting with accentuated horizontal force components provoked the highest loading within the medial and lateral pterygoids. The largest joint forces were also found for these bite directions. Conversely, the lowest joint forces were detected during vertical biting. Additionally, joint forces with a clear posterior orientation were found. Optimization strategies with the elastic energy as objective function revealed the best fit with the calculated results.
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Affiliation(s)
- H J Schindler
- Research Group Biomechanics, Faculty for Mathematics, University of Karlsruhe, D-76128, Karlsruhe, Germany.
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van Dijk J, Eiglsperger U, Hellmann D, Giannakopoulos N, McGill K, Schindler H, Lapatki B. Motor unit activity within the depth of the masseter characterized by an adapted scanning EMG technique. Clin Neurophysiol 2016; 127:3198-3204. [DOI: 10.1016/j.clinph.2016.05.186] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 04/07/2016] [Accepted: 05/16/2016] [Indexed: 10/21/2022]
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10
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Toro-Ibacache V, O'Higgins P. The Effect of Varying Jaw-elevator Muscle Forces on a Finite Element Model of a Human Cranium. Anat Rec (Hoboken) 2016; 299:828-39. [PMID: 27111484 DOI: 10.1002/ar.23358] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2015] [Revised: 02/22/2016] [Accepted: 03/08/2016] [Indexed: 11/07/2022]
Abstract
Finite element analyses simulating masticatory system loading are increasingly undertaken in primates, hominin fossils and modern humans. Simplifications of models and loadcases are often required given the limits of data and technology. One such area of uncertainty concerns the forces applied to cranial models and their sensitivity to variations in these forces. We assessed the effect of varying force magnitudes among jaw-elevator muscles applied to a finite element model of a human cranium. The model was loaded to simulate incisor and molar bites using different combinations of muscle forces. Symmetric, asymmetric, homogeneous, and heterogeneous muscle activations were simulated by scaling maximal forces. The effects were compared with respect to strain distribution (i.e., modes of deformation) and magnitudes; bite forces and temporomandibular joint (TMJ) reaction forces. Predicted modes of deformation, strain magnitudes and bite forces were directly proportional to total applied muscle force and relatively insensitive to the degree of heterogeneity of muscle activation. However, TMJ reaction forces and mandibular fossa strains decrease and increase on the balancing and working sides according to the degree of asymmetry of loading. These results indicate that when modes, rather than magnitudes, of facial deformation are of interest, errors in applied muscle forces have limited effects. However the degree of asymmetric loading does impact on TMJ reaction forces and mandibular fossa strains. These findings are of particular interest in relation to studies of skeletal and fossil material, where muscle data are not available and estimation of muscle forces from skeletal proxies is prone to error. Anat Rec, 299:828-839, 2016. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Viviana Toro-Ibacache
- Centre for Anatomical and Human Sciences, Department of Archaeology and Hull York Medical School, University of York, Heslington, York, YO10 5DD, UK
- Facultad De Odontología, Universidad De Chile, Sergio Livingstone Pohlhammer 943, Independencia, Región Metropolitana, Chile
| | - Paul O'Higgins
- Centre for Anatomical and Human Sciences, Department of Archaeology and Hull York Medical School, University of York, Heslington, York, YO10 5DD, UK
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José Campillo M, Miralles R, Santander H, Valenzuela S, Javiera Fresno M, Fuentes A, Zúñiga C. Influence of Laterotrusive Occlusal Scheme On Bilateral Masseter EMG Activity During Clenching and Grinding. Cranio 2014; 26:263-73. [DOI: 10.1179/crn.2008.036] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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12
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Gutiérrez MF, Miralles R, Fuentes A, Cavada G, Valenzuela S, Santander H, Fresno MJ. The Effect of Tooth Clenching and Grinding on Anterior Temporalis Electromyographic Activity in Healthy Subjects. Cranio 2014; 28:43-9. [DOI: 10.1179/crn.2010.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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13
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Rodríguez K, Miralles R, Felipe Gutiérrez M, Santander H, Fuentes A, Javiera Fresno M, Valenzuela S. Influence of Jaw Clenching and Tooth Grinding on Bilateral Sternocleidomastoid EMG Activity. Cranio 2014; 29:14-22. [DOI: 10.1179/crn.2011.004] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Aldana K, Miralles R, Fuentes A, Valenzuela S, Fresno MJ, Santander H, Gutiérrez MF. Anterior Temporalis and Suprahyoid EMG Activity During Jaw Clenching and Tooth Grinding. Cranio 2014; 29:261-9. [DOI: 10.1179/crn.2011.039] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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15
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Miralles R, Gallardo F, Baeza M, Valenzuela S, Ravera MJ, Ormeño G, Cavada G. Laterotrusive Occlusal Schemes and Jaw Posture Tasks Effects On Supra- and Infrahyoid EMG Activity in the Lateral Decubitus Position. Cranio 2014; 25:106-13. [PMID: 17508631 DOI: 10.1179/crn.2007.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
The purpose of this study was to determine the effect of canine guidance and group function on supra- and infrahyoid EMG activity in the lateral decubitus position at different jaw posture tasks. The sample included 40 healthy subjects with natural dentition and bilateral molar support, 20 with bilateral canine guidance and 20 with bilateral group function. An inclusion criterion was that subjects had to be free of signs and symptoms of any dysfunction of the masticatory system. Bipolar surface electrodes were located on the left supra- and infrahyoid muscles for EMG recordings. In the lateral decubitus position, EMG activity was recorded in subjects with canine guidance or group function, during the following jaw posture tasks: A. maximal clenching in the edge-to edge lateral contact position; B. grinding from intercuspal position to edge-to-edge lateral contact position, and C. grinding from edge-to-edge lateral contact position to intercuspal position. Supra- and infrahyoid EMG activity was not significantly different with canine guidance or group function (mixed model with unstructured covariance matrix). Overall comparison of suprahyoid or infrahyoid EMG activity among the three jaw posture tasks studied showed a significantly higher activity during jaw posture task A (clenching) than jaw posture tasks B and C (grinding). Suprahyoid EMG activity was significantly higher during jaw posture task C than B, whereas infrahyoid EMG activity did not present a significant difference between jaw posture tasks C and B. These EMG patterns observed could be of clinical importance in the presence of parafunctional habits, i.e., clenching and/or grinding. The neurophysiological mechanisms involved are discussed.
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Affiliation(s)
- Rodolfo Miralles
- Oral Physiology Laboratory, Biomedical Sciences Institute, Faculty of Medicine, University of Chile, Independencia 1027, Clasificador NO 7, Independencia, Santiago, Chile.
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Hellmann D, Giannakopoulos NN, Schmitter M, Lenz J, Schindler HJ. Anterior and posterior neck muscle activation during a variety of biting tasks. Eur J Oral Sci 2012; 120:326-34. [DOI: 10.1111/j.1600-0722.2012.00969.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/01/2012] [Indexed: 11/27/2022]
Affiliation(s)
- Daniel Hellmann
- Department of Prosthodontics; University of Heidelberg; Heidelberg; Germany
| | | | - Marc Schmitter
- Department of Prosthodontics; University of Heidelberg; Heidelberg; Germany
| | - Jürgen Lenz
- Research Group Biomechanics; Institute for Mechanics; Karlsruhe Institute of Technology (KIT); Karlsruhe; Germany
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17
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Neuromuscular control of balancing side contacts in unilateral biting and chewing. Clin Oral Investig 2011; 16:421-8. [DOI: 10.1007/s00784-011-0542-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2010] [Accepted: 03/04/2011] [Indexed: 01/04/2023]
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Rues S, Lenz J, Türp JC, Schweizerhof K, Schindler HJ. Muscle and joint forces under variable equilibrium states of the mandible. Clin Oral Investig 2010; 15:737-47. [PMID: 20585815 DOI: 10.1007/s00784-010-0436-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2009] [Accepted: 06/11/2010] [Indexed: 01/08/2023]
Abstract
It is well established that subjects without molars have reduced ability to comminute foods. However, epidemiological studies have indicated that the masticatory system is able to functionally adapt to the absence of posterior teeth. This supports the shortened dental arch concept which, as a prosthetic option, recommends no replacement of missing molars. Biomechanical modeling, however, indicates that using more anterior teeth will result in a larger temporomandibular joint load per unit of bite force. In contrast, changing bite from incisor to molar position increases the maximum possible bite force and reduces joint loads. There have been few attempts, however, to determine realistic joint loads and corresponding muscular effort during generation of occlusal forces similar to those used during chewing with intact or shortened dental arches. Therefore, joint and cumulative muscle loads generated by vertical bite forces of submaximum magnitude moving from canine to molar region, were calculated. Calculations were based on intraoral measurement of the feedback-controlled resultant bite force, simultaneous electromyograms, individual geometrical data of the skull, lines of action, and physiological cross-sectional areas of all jaw muscles. Compared to premolar and canine biting, bilateral and unilateral molar bites reduced cumulative muscle and joint loads in a range from 14% to 33% and 25% to 53%, respectively. During unilateral molar bites, the ipsilateral joints and contralateral muscles were about 20% less loaded than the opposing ones. In conclusion, unilateral or bilateral molar biting at chewing-like force ranges caused the least muscle and joint loading.
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Affiliation(s)
- Stefan Rues
- Research Group Biomechanics, Institute of Mechanics, Karlsruhe Institute of Technology, Karlsruhe, Germany.
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Schindler HJ, Lenz J, Türp JC, Schweizerhof K, Rues S. Influence of neck rotation and neck lateroflexion on mandibular equilibrium. J Oral Rehabil 2010; 37:329-35. [PMID: 20180896 DOI: 10.1111/j.1365-2842.2010.02064.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Neuromuscular interaction between neck and jaw muscles has been reported in several studies. However, the influence of experimentally modified posture of the neck on jaw muscle activity during isometric biting was not investigated so far. The aim of the present study was to test by the aid of simultaneous electromyographic and intraoral bite force measurements whether neck rotation and lateroflexion, in contrast to a straightforward neck position, change the isometric cocontraction patterns of masticatory muscles under identical submaximum bite forces of 50-200 N. Electric muscle activity of all masticatory muscles and changes of the reduction point (RP) of the resultant bite force vectors were examined. An anteroposterior displacement of the RPs could be observed for the rotated and lateroflexed neck position in comparison with the straightforward position. On the other hand, the results revealed no significant differences between bilateral muscle activation under the different test conditions. These findings suggest a force transmission between the neck and the masticatory system, but no essential activity changes in the masticatory muscles under short time posture modification of the neck.
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Affiliation(s)
- H J Schindler
- Research Group Biomechanics, Institute for Mechanics, University of Karlsruhe, Karlsruhe, Germany
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Pröschel PA, Morneburg TR. Indications for jaw gape-related control of relative muscle activation in sequent chewing strokes. J Oral Rehabil 2009; 37:178-84. [PMID: 19968765 DOI: 10.1111/j.1365-2842.2009.02036.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Jaw muscle activity ratios in unilateral isometric biting differ from ratios of unilateral chewing but approach the latter if the jaw gape in biting is made as small as the minimum interocclusal distance (MID) of chewing. Especially, the masseter working/balancing side ratio (W/B-ratio) becomes as asymmetric as in chewing, because of reduction in balancing side (BS) masseter activity. This behaviour of ratios might reflect a 'chewing-specific' motor strategy induced when isometric biting is performed with a 'chewing-like' gape. If this hypothesis applies, activity ratios should be associated with MIDs of sequent chewing strokes in a similar manner as with incremented jaw gapes in isometric biting. To test this prediction, bilateral surface electromyograms of masseter and anterior temporalis muscles and incisor movements were recorded during unilateral chewing in 52 subjects. W/B-ratios of masseter and temporalis activities and temporalis/masseter-ratios on both sides were calculated. The ratios were related to MIDs of consecutive chewing cycles. Three of the four ratios were associated with masticatory MID in the same manner as with jaw gape in isometric biting. In particular with decreasing MID, the masseter W/B-ratio increased from 1.5 to 2.2 (P < 0.01). This increase in asymmetry was attributed to a stronger decrease in masseter activity on the BS than on the working side. We conclude that relative jaw muscle activation is associated with interocclusal distance in a similar way in isometric biting and in chewing. This analogy supports the idea of a common jaw gape-related neuromuscular strategy facilitated by afferent signalling of interocclusal distance.
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Affiliation(s)
- P A Pröschel
- Dental Clinic 2, Department of Prosthodontics, University of Erlangen-Nürnberg, Erlangen, Germany.
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SCHINDLER HJ, LENZ J, TÜRP JC, SCHWEIZERHOF K, RUES S. Small unilateral jaw gap variations: equilibrium changes, co-contractions and joint forces. J Oral Rehabil 2009; 36:710-8. [DOI: 10.1111/j.1365-2842.2009.01985.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Venegas M, Valdivia J, Fresno MJ, Miralles R, Gutiérrez MF, Valenzuela S, Fuentes A. Clenching and grinding: effect on masseter and sternocleidomastoid electromyographic activity in healthy subjects. Cranio 2009; 27:159-66. [PMID: 19697643 DOI: 10.1179/crn.2009.024] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
This study compares the effect of clenching and grinding on masseter and sternocleidomastoid electromyographic (EMG) activity during different jaw posture tasks in the sagittal plane. The study included 34 healthy subjects with natural dentition, Class I bilateral molar Angle relationship, and absence of posterior occlusal contacts during mandibular protrusion. An inclusion criterion was that subjects had to be free of signs and symptoms of any dysfunction of the masticatory system. Bipolar surface electrodes were located on the right masseter and sternocleidomastoid muscles. EMG activity was recorded while the subjects were in standing position, during the following jaw posture tasks: A. maximal clenching in the intercuspal position; B. grinding from intercuspal position to edge-to-edge protrusive contact position; C. maximal clenching in the edge-to-edge protrusive contact position; D. grinding from edge-to-edge protrusive contact position to intercuspal position; E. grinding from retrusive contact position to intercuspal position. EMG activities in tasks B, C, D, and E were significantly lower than in task A in both muscles (mixed model with unstructured covariance matrix). EMG activity among tasks B, C, D, and E did not show significant differences in both muscles, except between tasks D and E in the masseter muscle. A higher effect was observed on the masseter than on the sternocleidomastoid muscle to avoid excessive muscular activity during clenching and grinding. The EMG patterns observed could be of clinical importance in the presence of parafunctional habits, i.e., clenching and/or grinding.
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Rues S, Lenz J, Türp JC, Schweizerhof K, Schindler HJ. Forces and motor control mechanisms during biting in a realistically balanced experimental occlusion. Arch Oral Biol 2008; 53:1119-28. [DOI: 10.1016/j.archoralbio.2008.06.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2007] [Revised: 06/18/2008] [Accepted: 06/25/2008] [Indexed: 11/25/2022]
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PRÖSCHEL PA, JAMAL T, MORNEBURG TR. Motor control of jaw muscles in chewing and in isometric biting with graded narrowing of jaw gape. J Oral Rehabil 2008; 35:722-8. [DOI: 10.1111/j.1365-2842.2008.01871.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Rues S, Schindler HJ, Türp JC, Schweizerhof K, Lenz J. Motor behavior of the jaw muscles during different clenching levels. Eur J Oral Sci 2008; 116:223-8. [DOI: 10.1111/j.1600-0722.2008.00537.x] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Schindler HJ, Rues S, Türp JC, Lenz J. Heterogeneous activation of the medial pterygoid muscle during simulated clenching. Arch Oral Biol 2006; 51:498-504. [PMID: 16405862 DOI: 10.1016/j.archoralbio.2005.11.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2005] [Revised: 11/22/2005] [Accepted: 11/24/2005] [Indexed: 10/25/2022]
Abstract
The aim of this study was to investigate whether the medial pterygoid muscle shows differential activation under experimental conditions simulating force generation during jaw clenching. To answer this question, the electromyographic activity of the right medial pterygoid was recorded with two intramuscular electrodes placed in an anterior and posterior muscle region, respectively. Intraoral force transfer and force measurement were achieved by a central bearing pin device equipped with strain gauges. The activity distribution in the muscle was recorded in a central mandibular position during generation of eight different force vectors at a constant amount of force (F=150 N). The investigated muscle regions showed different amounts of EMG activity. The relative intensity of the activation in the two regions changed depending on the task. In other words, the muscle regions demonstrated heterogeneous changes of the EMG pattern for various motor tasks. The results indicate a heterogeneous activation of the medial pterygoid muscle under test conditions simulating force generation during clenching. This muscle behaviour might offer an explanatory model for the therapeutic effects of oral splints.
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Affiliation(s)
- Hans J Schindler
- Research Group Biomechanics, Faculty for Mathematics, University of Karlsruhe, Germany.
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