Symmetry evaluation of the craniofacial complex generally involves models of mandibular movement and masticatory muscle activity, especially during the growth of the craniofacial complex. Objectives: The aim of the study was to determine what, if any, associations exist between the activity of the masticatory muscles, sex, and occlusal classes in asymptomatic young adults. Methods:18-year-old volunteers, showing no symptoms of TMD based on an RDC/TMD examination, were included in the study.Surface electromyography (sEMG) recording was used to quantify the activity of masticatory muscles. The occlusal contact points were analyzed using a T-scan III Evolution 7.01 device. Occlusal classes were graded, employing an approach based on plaster study models. Results: In Class I–II subjects, we found significant differences only in the voltage of LTA in correlation with the gender and occlusal Class. Conclusions: Our findings show that the electromyography voltage of LTA significantly differs according to sex and occlusal Class. The voltage is higher in the female occlusal class II group, while the voltage is less in the male Class I and II group. This may be responsible for the symmetry index, which shows the predominance of the right-side muscles in all gender and occlusal groups.


  1. Okeson JP. Managmenet of temporomanbibular disorders and occlusion7 ed. Elsevier Mosby, 2013.
  2. Kołodziejczyk K, Kawala B, Kawala M, Bednarska J, Antoszewska-Smith J. Emg vs precision and accurancy in dentistry. Dental and Medical Problems. 2015;52:466-471.
  3. Ferrario VF, Sforza C, Colombo A, Ciusa V. An electromyographic investigation of masticatory muscles symmetry in normo-occlusion subjects. J Oral Rehabil. 2000;27:33-40.
  4. Ferrario VF, Sforza C, Miani A, Jr., D'Addona A, Barbini E. Electromyographic activity of human masticatory muscles in normal young people. Statistical evaluation of reference values for clinical applications. J Oral Rehabil. 1993;20:271-280.
  5. Osiewicz MA, Loster JE, Wieczorek A, Loster BW. Reliability assessment of the polish version of a questionnaire of the research diagnostic criteria for temporomandibular disorders – axis ii. J Stoma. 2014;67:166-174.
  6. Osiewicz MA, Lobbezoo F, Loster BW, Wilkosz M, Naeije M, Ohrbach R. Research diagnostic criteria for temporomandibular disorders (rdc/tmd) - the polish version of a dual-axis system for the diagnosis of tmd. Rdc/tmd form. J Stoma. 2013;66:576-649.
  7. Osiewicz, M, Loster J, Wieczorek A, Loster B. Reliability assessment of the examination of the sounds in temporomandibular joints in a polish patient population. J Dent Indones. 2019;26(3): 140-144
  8. Loster JE, Osiewicz MA, Groch M, Ryniewicz W, Wieczorek A. The Prevalence of TMD in Polish Young Adults. J Prosthodont. 2017 Jun;26(4):284-288.
  9. Baldini A, Nota A, Cozza P. The association between occlusion time and temporomandibular disorders. J Electromyogr Kinesiol. 2015;25:151-154.
  10. Wieczorek A, Loster J, Loster BW. Relationship between occlusal force distribution and the activity of masseter and anterior temporalis muscles in asymptomatic young adults. Biomed Res Int. 2013;2013:354017
  11. Ciavarella D, Parziale V, Mastrovincenzo M, Palazzo A, Sabatucci A, Suriano MM, Bossu M, Cazzolla AP, Lo Muzio L, Chimenti C. Condylar position indicator and t-scan system ii in clinical evaluation of temporomandibular intracapsular disease. J Craniomaxillofac Surg. 2012;40:449-455.
  12. Sierpinska T, Jacunski P, Kuc J, Golebiewska M, Wieczorek A, Majewski S. Effect of the dental arches morphology on the masticatory muscles activities in normal occlusion young adults. Cranio. 2015;33:134-141.
  13. Wozniak E, Loster JE, Wieczorek A. Relation between headache and mastication muscle tone in adolescents. Pain Research and Management, vol. 2018, Article, ID 7381973, 7 pages, 2018.
  14. Li J, Jiang T, Feng H, Wang K, Zhang Z, Ishikawa T. The electromyographic activity of masseter and anterior temporalis during orofacial symptoms induced by experimental occlusal highspot. J Oral Rehabil. 2008;35:79-87.
  15. Wieczorek A, Loster JE. Activity of the masticatory muscles and occlusal contacts in young adults with and without orthodontic treatment. BMC Oral Health. 2015;15(1):116
  16. Naeije M, McCarroll RS, Weijs WA. Electromyographic activity of the human masticatory muscles during submaximal clenching in the inter-cuspal position. J Oral Rehabil. 1989;16:63-70.
  17. Stocka A, Kuc J, Sierpinska T, Golebiowska M, Wieczorek A. The influence of emotional state on the masticatory muscles function in the group of young healthy adults. Biomed Res Int. 2015;2015:174013.
  18. Suvinen TI, Kemppainen P. Review of clinical emg studies related to muscle and occlusal factors in healthy and tmd subjects. J Oral Rehabil. 2007;34:631-644.


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