Background and objectives: Many reports have described neurosensory disturbances on Inferior Alveolar Nerve (IAN) after mandibular Bilateral Sagittal Split Osteotomy (BSSO). Paresthesia after BSSO has been reported between 12.5% and 100%. Our aim is to determine the percentage of the sensorial recovery of the area innervated by NAI after BSSO until the first year post surgery. This study is part of an investigation that is being performed since June of 2012 at Dental School of the Universidad de Chile with Hospital San Borja Arriaran, both located in Santiago, Chile. This study will have a sample of 30 patients. This is a preliminary report of the evolution of 15 patients who have completed 6 months post surgery.

Methods: Were included 15 patients with dentofacial deformities Classes II and III diagnosis who underwent orthognathic surgery with BSSO technique. The patients were controlled at 1st, 3rd and 6th month post surgery. The zone of study included a rectangular area of chin (gridded in 8 equal parts) limited superiorly by a line from labial commissure prolonged to 1 cm to distal of each side and the lower limit is the basilar edge. The squares were stimulated just one time each, using a von Frey calibrated monofilament. Patient reported the sensation using a hypoesthesia scale (previously explicated to him).

Results: At 1 month after surgery was registered a 26.2% of sensitivity in the study area, in the third month was registered a 41.8% meanwhile at the sixth post surgery month was registered a 55% of sensitivity.

Conclusion: The sensorial recovery is progressive and shows a rising pattern until 6th month after surgery where the patient is able to discriminate the stimulated points. In this preliminary report is not possible to determine a concentric/eccentric pattern of sensorial recovery at 6th month post surgery.

Key words: osteotomy; hypoesthesia; neuropraxia