Methods: In this experimental study, 30 healthy subjects with natural dentition and healthy muscles were tested. Having located the Bipolar surface electrodes on the right anterior temporal and masseter muscles, EMG (MT8, MIE British Company) record was taken. Vertical dimension of rest position (VDR) was measured while performing the following jaw posture tasks: during and after pronouncing the word “Maryam”, during and after swallowing of saliva, and while maintaining their mandible in a relaxed posture.
Results: The mean voltage of masseter and anterior temporal muscle shows that there is a significant difference between mean voltage of swallowing method and phonetic, absolute rest (P<0.05); but there is no significant difference between mean voltage of phonetic and absolute rest (P>0.05). Also mean VDR shows that there is significant difference between all mentioned methods (P<0.05). The most measured rate is related to absolute rest, phonetic and rest posture after swallowing respectively.
Conclusions: The results provide scientific evidence that all mentioned methods can be used; and if there is difference, mean measured rates will be applied.