Impact of midface and upper face fracture on bite force, mandibular mobility, and electromyographic activity

This study evaluated the bite force, electromyographic activity, and mandibular mobility in patients undergoing surgery for facial fracture treatment that required a coronal approach. Ten men were divided into two groups: group I, coronal approach with pre-auricular extension (n = 4, average age 34.5 years); group II, coronal approach (n = 6, average age 24.8 years). The maximum bite force was measured using a dynamometer and mandibular mobility using a calliper. The electromyographic activity of the right masseter (RM), left masseter (LM), right temporal (RT), and left temporal (LT) muscles was evaluated using a Myosystem-Br1 apparatus. Patients were evaluated at 1, 2, 3, and 6 months after surgery. Data were analysed using the repeated measures test (SPSS 21.0; P ≤ 0.05). Statistically significant differences were found for electromyographic activity at rest (group II: LM P = 0.00), left laterality (group I: RT P = 0.02; group II: RT P = 0.04), and maximum voluntary contraction (group I: RM P = 0.04 and RT P = 0.04; group II: RM P = 0.05, LM P = 0.00, and LT P = 0.01 and for maximum molar bite force in the right (group I, P = 0.00; group II, P = 0.01) and left (group II, P = 0.01) molar regions. The subjects regained electromyographic activity, maximum bite force, and mandibular mobility throughout the period evaluated.