Methodology of the sagittal split osteotomy of the mandible improved from year to year. However, there is still the problem of neurosensory disorders of inferior alveolar nerve in the early and late postoperative period is widely covered in the foreign literature. The incidence of these disorders ranges from 40 to 55%. During 2009-2013 years in Central Research Institute of Stomatology and Maxillofacial Surgery were operated 127 patients with associated deformities of the jaws: 102 according to traditional methods, 25 - by improved methods. Assessment of lower alveolar nerve conducted by electric teeth pulp test methods, blink reflex, computed tomography in 3D mode and the questionnaire. The results showed that the improved method of the sagittal split osteotomy of the mandible by using piezoelectric bone surgery saw during cutting of the cortical bone of the mandible and special splitters with replacing of damaging factors makes it possible to reduce the incidence of neurosensory disorders of inferior alveolar nerve and reduce the time of rehabilitation.