Purpose: Data on intraoperative risk factors for long-term postoperative complications after Le Fort I osteotomy (LFO) are limited. The aim of this study was to describe prospectively the overall postoperative changes in maxillary nerve function after LFO, and to correlate these changes with a number of possible intraoperative risk factors. Patients and Methods: Twelve men and 13 women (mean +/- standard deviation: aged 25 +/- 10 years) participated in 4 sessions: 1 before LFO (baseline), and the rest at 3, 6, and 12 months after LFO. At each session, somatosensory sensitivity was assessed for the skin, oral mucosa, and teeth, using quantitative sensory tests at either I cutaneous point or on a 5 x 5 point matrix reproduced on the skin. In addition, all patients were asked to report their perceived differences in somatosensory sensitivity and their overall satisfaction with the LFO. Results: The thresholds of tactile stimuli on the gingiva and palate were increased 12 months after LFO (P < .001). Significant increases in 2-point discrimination detection thresholds (P < .01) and increased sensitivity to heat (P < .01) and cold (P < .001) in the infraorbital region were also recorded 12 months after LFO. Correspondingly, seff-reported complaints of changed sensation under the eyes (P < .01), upper lip (P < .01), gingiva (P < .001), palate (P < .01), and teeth (P < .01) were reported during the entire postoperative period. Intraoperative risk factors were identified and correlated with postoperative changes in somatosensory sensitivity. Segmentation of the maxilla was associated with an increase in tactile thresholds at the palate and gingiva (P < .05), as were self-reported complaints involving the palate and gingiva (P < .001), whereas maxillary impaction was related to lower-tooth pulp pain thresholds when compared with maxillary lowering (P < .01). All patients expressed satisfaction with LFO, despite signs of somatosensory disturbances in up to 64% of patients. Conclusion: Numerous changes in postoperative somatosensory function are to be expected after LFO. In most patients, these changes are minor, and some are dependent on intraoperative procedures. Nonetheless, all patients reported satisfaction with the Surgical results, and would recommend the procedure to others. (C) 2009 American Association of Oral and Maxillofacial Surgeons