Maximum Bite Force of Skeletal Class II Pa-tients Between 18-30 Years Before and After Orthognathic Surgery

The bite force changes due to alterations in the lever system of the jaw following orthognathic surgery. This study aimed to assess the changes in the maximum bite force of skeletal Class II patients between 18-30 years after orthognathic surgery compared with the preoperative state.

This inception cohort study evaluated 17 patients with skeletal Class II malocclusion (mandibular deficiency) and normal vertical dimension between 18-30 years who underwent mandibular advancement surgery. The maximum bite force on the mandibular first molars was measured preoperatively and at 6 weeks, and 3 and 6 months, postoperatively. The overjet and overbite were also measured on diagnostic casts. Data were analyzed by the Shapiro-Wilk test, Mauchly’s test, the Greenhouse–Geisser correction, and the Spearman and Pearson’s correlation coefficients. 

The mean maximum bite force preoperatively was significantly higher than that at 6 weeks (P<0.001), 3 months (P<0.001), and 6 months (P<0.001), postoperatively. No significant difference was noted in the mean bite force in the right and left sides of the jaw (P=0.589). The overbite and maximum bite force were not significantly correlated in the right (P=0.181) or the left (P=0.134) side, preoperatively. The overjet had no significant correlation with the maximum bite force in the right (P=0.881) or the left (P=0.677) side, preoperatively.

Mandibular advancement surgery in skeletal Class II patients with mandibular deficiency decreases the maximum bite force in the first 6 months, postoperatively.