Abstract
Functional impairment of mandibular movement after sagittal split osteotomy in 21 skeletal Class III patients was studied. Mandibular movement was recorded and analyzed by a six-degrees-of-freedom optoelectric mandibular motion recording system (Gnathohexagraph®, JM-1000T, Ono Sokki, Japan). Mandibular movements were recorded preoperatively, and at 1, 2, 3, 6, and 12 month postoperatively. Mandibular movement was evaluated by analyzing the parameters of mandibular incisor paths. The subjects performed protrusive, lateral excursions and maximal open-close movement of the mandible and habitual open-close cycles of the mandible.
The values of protrusive and lateral excursions of the incisor at one month after surgery decreased by 25%, and functional recovery was significant at 12 months after surgery. The capacity of maximal opening of the jaw decreased by 43% at one month after surgery, and the opening capacity regained approximately 90% of the level at 12 months after surgery. A significant difference was found between males and females in the velocity of the open-close cycles. Male subjects showed a slight decrease in velocity one month after surgery, and the value reached 125% 12 months later. Female subjects showed a remarkable decrease in velocity one month after surgery and remained at 10% below the presurgical level. The results of this study indicated that functional impairment of mandibular movement after sagittal split osteotomy was achieved within one year, as well as restoration of the dentoskeletal morphology to its former condition.
