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
236 STOMA. EDUJ( 2016) 3( 2)