EMG analysis of trapezius and masticatory muscles: experimental protocol and data reproducibility

Abstract

We aimed to define a standardised protocol for the electromyographic evaluation of trapezius muscle in dentistry and to assess its within- and between-session repeatability. Surface electromyography of trapezius, masseter and temporal muscles was performed in 40 healthy subjects aged 20-35 years during shoulder elevation, and maximum teeth clenching with and without cotton rolls. Two repetitions were made both within (same electrodes) and between sessions (different electrodes). Maximum voluntary clench on cotton rolls was used to standardise the potentials of the six analysed muscles with tooth contact; shoulder elevation was used to standardise the upper trapezius potentials. From the standardised electromyographic potentials, several indices (muscle symmetry; masticatory muscle torque and relative activity; total masticatory muscle activity; trapezius cervical load, percentage co-contraction of trapezius during teeth clenching) were computed; random (technical error of measurement) and systematic (Student's t-test, Analysis of Variance) errors were assessed. For all indices, no systematic errors were found between the two separate data collection sessions. Within session, limited (lower than 8%) technical errors of measurement were found for temporalis and masseter symmetry, torque and activity indices, and the trapezius cervical load. Larger random errors were obtained for trapezius symmetry and total masticatory muscle activity (up to 20%). Between sessions, no significant differences were found for trapezius co-contraction. In conclusion, a protocol for the standardisation of trapezius muscle that may be used within dental clinical applications was defined, and the repeatability of masseter, temporalis and trapezius electromyographic recordings for serial assessments was assessed in healthy subjects.

EMG spectral characteristics of masticatory muscles and upper trapezius during maximum voluntary teeth clenching

“…Considering that upper trapezius muscle contraction during MVC is generally of low intensity (Ceneviz et al, 2006;Forrester et al, 2010;Learreta et al, 2007;Sforza et al, 2011;Tecco et al, 2007Tecco et al, , 2011Zuniga et al, 1995), we choose to include in the current study only subjects who had a contraction level equal to or larger than 10% of their maximal contraction, in accordance with the protocol by Kumar et al (2001). The experimental set up did not include a force transducer, as extensively discussed by Sforza et al (2011), and the EMG signal was used instead.…”

“…The same experimental protocol detailed by Sforza et al (2010Sforza et al ( , 2011 was used. In brief, sEMG of the right and left masseter, anterior temporalis and upper trapezius muscles was recorded during the performance of two maximum voluntary teeth clenching (MVC) tests.…”

“…Among the others, surface electromyography (sEMG) is currently used to make an objective recording of the muscle function and dysfunction (Castroflorio et al, 2008;De Felício et al, 2009;Ferrario et al, 2007;Forrester et al, 2010;Grünheid et al, 2009;Kumar et al, 2001Kumar et al, , 2003Pallegama et al, 2004;Sforza et al, 2010Sforza et al, , 2011Suvinen et al, 2003Suvinen et al, , 2009Tartaglia et al, 2008aTartaglia et al, ,b, 2011Tecco et al, 2008Tecco et al, , 2011. sEMG is a non-invasive, low cost examination that can be made directly in the dental office, without the necessity of sending the patient to specialized diagnostic centres (Castroflorio et al, 2008;Ferrario et al, 2006Ferrario et al, , 2007Forrester et al, 2010;Learreta et al, 2007;Pallegama et al, 2004;Sforza et al, 2010Sforza et al, , 2011Tartaglia et al, 2008bTartaglia et al, , 2011.…”

“…Among the others, maximum voluntary teeth clenching (MVC) either in intercuspal position or on cotton rolls is one of the most used tests (Forrester et al, 2010;Tartaglia et al, 2011;Tecco et al, 2011). MVC induces some co-contraction in the upper trapezius muscle (Ceneviz et al, 2006;Forrester et al, 2010;Learreta et al, 2007;Sforza et al, 2011;Tecco et al, 2007Tecco et al, , 2011Zuniga et al, 1995).…”

“…sEMG is a non-invasive, low cost examination that can be made directly in the dental office, without the necessity of sending the patient to specialized diagnostic centres (Castroflorio et al, 2008;Ferrario et al, 2006Ferrario et al, , 2007Forrester et al, 2010;Learreta et al, 2007;Pallegama et al, 2004;Sforza et al, 2010Sforza et al, , 2011Tartaglia et al, 2008bTartaglia et al, , 2011.…”