ABSTRACT
<p><b>OBJECTIVE</b>To investigate the effect of muscular rehabilitation on recovery after sagittal split ramus osteotomy.</p><p><b>METHODS</b>Twenty-seven patients undergoing sagittal split ramus osteotomy received passive motion training and muscle endurance training after surgery using the new-developed mouth-opening trainer. The passive motion training began 2-3 days after the removal of inter-maxillary elastraction. The instrument was inserted into the inter-maxillary space for 5 min per time, 3-4 times per day. When the mouth opening reached a range of 20-25 mm, the muscle endurance training initiated. The results of the training were compared with another 20 cases who received the same surgery.</p><p><b>RESULTS</b>The mouth opening of the patients who received muscular rehabilitation achieved the pre-surgical level 4 weeks after surgery [(34.72 ± 3.75) mm], the bite force reached the pre-surgical level 8 weeks after surgery [(231.08 ± 62.52) N], but in the 20 cases without training the mouth opening [(28.42 ± 4.11) mm] in 4 weeks and the bite force in 8 weeks [(210.90 ± 73.40) N] were lower after surgery than before surgery.</p><p><b>CONCLUSIONS</b>The systematic and standard muscle function training, accompanied with the use of the new-developed mouth-opening trainer could improve the functional recovery of the patients who receive sagittal split ramus osteotomies.</p>