Study on the association of ultrasonographic thickness and electromyographic activity of masseter muscle in young females with different vertical craniofacial morphology.

Purpose: To study the relationship between ultrasonographic thickness and EMG activity of the masseter muscle in subjects with different vertical craniofacial morphology.

Methods: Thirty female students were separated into two groups (14 cases with high-angle, 16 cases with low-angle) based on SN-MP angle, FH-MP angle, and FHI. The thickness of the masseter muscle under relaxed conditions and during maximal clenching was assessed by ultrasonography.