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Sugano T, Ogawa T, Yoda N, Hashimoto T, Shobara K, Niizuma K, Kawashima R, Sasaki K. Morphological comparison of masseter muscle fibers in the mandibular rest and open positions using diffusion tensor imaging. J Oral Rehabil 2022; 49:608-615. [PMID: 35334120 DOI: 10.1111/joor.13319] [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: 12/27/2021] [Revised: 02/22/2022] [Accepted: 03/19/2022] [Indexed: 12/01/2022]
Abstract
BACKGROUND The masseter muscle has a complicated multipennate internal structure and exhibits functional differentiation when performing various stomatognathic functions. It is important to understand the internal structural changes of the muscle during functioning to elucidate characteristic muscle disorders such as local myalgia. Diffusion tensor imaging (DTI) may be useful for investigating the internal structural features of muscle. OBJECTIVES To evaluate the features of masseter muscle fibers in human participants using DTI fiber tractography, and to elucidate the structural differences in the masseter muscle between the mandibular rest and open positions. METHODS Five healthy men (age 31±7 years) underwent DTI and T1-weighted MRI of the right masseter muscle in the mandibular rest and open positions. MR images were used as a reference for muscle layer segmentation (superficial, intermediate, and deep). DTI fiber tractography of the masseter muscle was performed and the orientation of the DTI fibers was analyzed in each layer using coordinates based on the Frankfurt horizontal plane. RESULTS The DTI fiber orientation of the deep layer significantly changed between the mandibular rest and open positions in the frontal plane (p<0.05, Wilcoxon rank sum test). However, no significant change was found in the superficial and intermediate layers. CONCLUSION DTI fiber tractography confirmed regional differences in the orientation change of the masseter muscle fibers between different mandibular positions. The results may support the existence of functional partitioning inside the masseter muscle and suggest that DTI may be useful for the evaluation of muscle fibers in multipennate muscles.
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Affiliation(s)
- Takehiko Sugano
- Division of Advanced Prosthetic Dentistry, Tohoku University Graduate School of Dentistry, Japan
| | - Toru Ogawa
- Division of Advanced Prosthetic Dentistry, Tohoku University Graduate School of Dentistry, Japan
| | - Nobuhiro Yoda
- Division of Advanced Prosthetic Dentistry, Tohoku University Graduate School of Dentistry, Japan
| | - Teruo Hashimoto
- Institute of Development, Aging and Cancer, Tohoku University, Japan
| | - Kenta Shobara
- Division of Advanced Prosthetic Dentistry, Tohoku University Graduate School of Dentistry, Japan
| | - Kuniyasu Niizuma
- Department of Neurosurgical Engineering and Translational Neuroscience, Graduate School of Biomedical Engineering, Tohoku University, Japan.,Department of Neurosurgical Engineering and Translational Neuroscience, Tohoku University Graduate School of Medicine, Japan.,Department of Neurosurgery, Tohoku University Graduate School of Medicine, Japan
| | - Ryuta Kawashima
- Institute of Development, Aging and Cancer, Tohoku University, Japan
| | - Keiichi Sasaki
- Division of Advanced Prosthetic Dentistry, Tohoku University Graduate School of Dentistry, Japan
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Sugano T, Yoda N, Ogawa T, Hashimoto T, Shobara K, Niizuma K, Kawashima R, Sasaki K. Application of Diffusion Tensor Imaging Fiber Tractography for Human Masseter Muscle. TOHOKU J EXP MED 2022; 256:151-160. [DOI: 10.1620/tjem.256.151] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Takehiko Sugano
- Division of Advanced Prosthetic Dentistry, Tohoku University Graduate School of Dentistry
| | - Nobuhiro Yoda
- Division of Advanced Prosthetic Dentistry, Tohoku University Graduate School of Dentistry
| | - Toru Ogawa
- Division of Advanced Prosthetic Dentistry, Tohoku University Graduate School of Dentistry
| | - Teruo Hashimoto
- Institute of Development, Aging and Cancer, Tohoku University
| | - Kenta Shobara
- Division of Advanced Prosthetic Dentistry, Tohoku University Graduate School of Dentistry
| | - Kuniyasu Niizuma
- Department of Neurosurgical Engineering and Translational Neuroscience, Graduate School of Biomedical Engineering, Tohoku University
| | - Ryuta Kawashima
- Institute of Development, Aging and Cancer, Tohoku University
| | - Keiichi Sasaki
- Division of Advanced Prosthetic Dentistry, Tohoku University Graduate School of Dentistry
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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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Al Sayegh S, Vasilatou I, Kumar A, Al Barwari C, Fredriksson L, Grigoriadis A, Christidis N. Experimental pain and fatigue induced by excessive chewing. BMC Oral Health 2020; 20:179. [PMID: 32600327 PMCID: PMC7322929 DOI: 10.1186/s12903-020-01161-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2020] [Accepted: 06/08/2020] [Indexed: 12/18/2022] Open
Abstract
Background The study was aiming to optimize excessive gum chewing as an experimental model to induce jaw muscle pain and fatigue similar to those in painful TMDs with durations that would allow immediate investigations of jaw-motor function. Further, if any sex differences would be detected in the expression of pain. Methods This randomized, double blinded study included 31 healthy participants of both sexes. A standardized chewing protocol of either 40- or 60-min of chewing was used with a wash-out period of 1 week. Subjective fatigue, pain characteristics and functional measures were assessed. For statistical analyses, Wilcoxon Signed Rank test, Mann–Whitney Rank Sum test and Friedman’s ANOVA with Tukey post-hoc test were used. Results High subjective fatigue scores that lasted up to 20 min after the end of the trial were significantly induced both in the 40- and 60-min chewing trials (P < 0.001*). Significant but mild pain was induced only in the 60-min trial (P = 0.004*) and only in men (P = 0.04*). Also, the induced pain area was significantly bigger in the 60-min trial (P = 0.009*). However, this increase in pain and pain area did not last to the first 10-min follow-up. There were no significant differences neither between the 40- and 60-min chewing trials, except regarding the pain area (P = 0.008*), nor between the sexes. Conclusion Taken together, excessive chewing in its current form does not seem to be a proper pain experimental model. The model needs further adjustments in order to mimic TMD-pain especially in women and to prolong the pain duration.
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Affiliation(s)
- Samaa Al Sayegh
- Division of Oral Diagnostics and Rehabilitation, Department of Dental Medicine, Karolinska Institutet, Box 4046, SE-141 04, Huddinge, Sweden. .,Scandinavian Center for Orofacial Neurosciences (SCON), Huddinge, Sweden.
| | - Ioanna Vasilatou
- Division of Oral Diagnostics and Rehabilitation, Department of Dental Medicine, Karolinska Institutet, Box 4046, SE-141 04, Huddinge, Sweden
| | - Abhishek Kumar
- Division of Oral Diagnostics and Rehabilitation, Department of Dental Medicine, Karolinska Institutet, Box 4046, SE-141 04, Huddinge, Sweden.,Scandinavian Center for Orofacial Neurosciences (SCON), Huddinge, Sweden
| | - Ceva Al Barwari
- Division of Oral Diagnostics and Rehabilitation, Department of Dental Medicine, Karolinska Institutet, Box 4046, SE-141 04, Huddinge, Sweden
| | - Lars Fredriksson
- Department of Clinical Oral Physiology at the Eastman Institute, Folktandvården Stockholms län AB, SE-113 24, Stockholm, Sweden
| | - Anastasios Grigoriadis
- Division of Oral Diagnostics and Rehabilitation, Department of Dental Medicine, Karolinska Institutet, Box 4046, SE-141 04, Huddinge, Sweden.,Scandinavian Center for Orofacial Neurosciences (SCON), Huddinge, Sweden
| | - Nikolaos Christidis
- Division of Oral Diagnostics and Rehabilitation, Department of Dental Medicine, Karolinska Institutet, Box 4046, SE-141 04, Huddinge, Sweden.,Scandinavian Center for Orofacial Neurosciences (SCON), Huddinge, Sweden
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Nozad Mojaver Y, Tawadros PB, Moura Ferreira P, Whittle T, Murray GM. Single motor units from the medial pterygoid muscle can be active during isometric horizontal and vertical forces. J Oral Rehabil 2019; 46:998-1008. [PMID: 31206789 DOI: 10.1111/joor.12831] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 05/30/2019] [Accepted: 06/09/2019] [Indexed: 12/27/2022]
Abstract
OBJECTIVES To determine (a) whether the medial pterygoid muscle is active in an isometric vertical force task and in isometric horizontal force tasks in the contralateral, protrusion and ipsilateral directions; (b) whether the same single motor units (SMUs) could be active across different directions of isometric force generation; and (c) whether different regions of the medial pterygoid muscle exhibit different patterns of SMU activation during the generation of any one direction of isometric force. METHODS Intramuscular electromyographic (EMG) recordings were made from the right medial pterygoid muscle in 15 healthy participants during isometric force tasks: vertical and horizontal contralateral, protrusion and ipsilateral. A computed tomography scan divided the EMG recording site into a medial or lateral part in each participant. Single motor units were discriminated in each task. RESULTS Medial pterygoid SMU activity was recorded in 100% of participants for the vertical biting tasks, 86% of participants for the horizontal contralateral and horizontal protrusion tasks and 57% of the horizontal ipsilateral tasks. Of the 72 SMUs that were discriminated, 36% were active in all tasks; 18% were active only in the vertical tasks and 17% were active in the vertical, horizontal contralateral and horizontal protrusion tasks. The proportion of SMUs that was active in at least 1 horizontal task in the lateral part (33/39) was significantly higher than the proportion (21/33) in the medial part (Chi-Square, P < 0.05). CONCLUSION The data are consistent with a stabilisation role for the medial pterygoid muscle in isometric jaw forces in the vertical and horizontal planes.
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Affiliation(s)
- Yalda Nozad Mojaver
- Jaw Function and Orofacial Pain Research Unit, Sydney Dental School, Faculty of Medicine and Health, Westmead Hospital Centre for Oral Health, The University of Sydney, Westmead, New South Wales, Australia
| | - Paul B Tawadros
- Jaw Function and Orofacial Pain Research Unit, Sydney Dental School, Faculty of Medicine and Health, Westmead Hospital Centre for Oral Health, The University of Sydney, Westmead, New South Wales, Australia
| | - Polyana Moura Ferreira
- Jaw Function and Orofacial Pain Research Unit, Sydney Dental School, Faculty of Medicine and Health, Westmead Hospital Centre for Oral Health, The University of Sydney, Westmead, New South Wales, Australia
| | - Terry Whittle
- Jaw Function and Orofacial Pain Research Unit, Sydney Dental School, Faculty of Medicine and Health, Westmead Hospital Centre for Oral Health, The University of Sydney, Westmead, New South Wales, Australia
| | - Greg M Murray
- Jaw Function and Orofacial Pain Research Unit, Sydney Dental School, Faculty of Medicine and Health, Westmead Hospital Centre for Oral Health, The University of Sydney, Westmead, New South Wales, Australia
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