STANDARDIZED ELECTROMYOGRAPHIC INDEXES ALLOW A RELIABLE MEASUREMENT OF MASTICATORY MUSCLES FUNCTION
Figure 1 . Masseter and Temporalis Anterior electrode placement
Figure 2 . Initial clinical condition
Figure 3 . Initial sEMG differential test . Reported indexes are : Temporalis Anterior and Masseter percentage overlapping coefficient ( POC TA and POC MM ); activity index ( ACTIV ); torque coefficient ( TORQUE ) and standardized activity index ( IMPACT )
normalized indexes obtained during maximal voluntary clenching sEMG acquisitions .
2 . Methodology 2.1 . Study design Standardized cutaneous myoelectric activity of Temporalis Anterior and Masseter muscles was acquired twice with a one-week interval ( Acquisition sessions T1 and T2 ) in 20 young healthy adults . The data obtained during T1 and T2 were compared . 2.2 . Subjects Twenty young healthy adult volunteers ( 5 males , 15 females , age range 24-28 years , mean 26 , SD 2 ), volunteers were recruited for the study after a detailed explanation of the experimental protocol and possible risks involved . They all gave their consent to the investigation according to the principles outlined in the Declaration of Helsinki . The study protocol was approved by the local ethic committee . All data collections were performed in the clinic of Dental Faculty of North-Western State Medical University named after I . I . Mechnikov ( Saint Petersburg , Russian Federation ).
Figure 4 . Resin jig used to arrange vertical dimension following muscle performance
The subjects were visited by a dentist ( SE ); all the subjects were in general good health , free from stomatognathic apparatus and neck pathologies and were selected for the study according to the following inclusion criteria : a minimum of 28 permanent teeth , no parodontal problems , no craniofacial and cervical trauma and surgery , no temporo-mandibular and craniocervical disorders , no current orthodontic treatment and
no painful sensation when clenching their teeth . The subjects were excluded from the study if they had neurological problems that could interfere with the experimental procedure , or if they were taking drugs that could affect the musculoskeletal system , such as anti-inflammatory or pain relief drugs . During the sEMG recording , the environment was quiet and with low light . The subjects sat in a comfortable office type chair , in an erect posture with
their feet flat on the floor , and arms resting on their legs . 2.3 . Electrode type and positioning The Masseter ( MM ) and Temporalis Anterior ( TA ) muscles of both sides ( left and right ) were examined . Disposable pre-gelled silver / silver
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