Three-dimensional soft tissue changes at nasolabial region after orthognathic surgery in 88 female patients with maxillary protrusion

Objective To evaluate the three-dimensional soft tissue changes at nasolabial region of female patients with maxillary protrusion after orthognathic surgery with maxillary setback. Methods Peking University School and Hospital of Stomatology admitted 88 female patients with maxillary protrusion, aged 18-42 years old, with an average age of 28.2 years old. The segmental Le Fort Ⅰ osteotomies were performed in all patients with extraction of maxillary first premolars to create space for maxillary setback. The patients with maxillary protrusion and mandibular retraction received bilateral sagittal split ramus osteotomy(BSSRO)to move mandibular body, while the patients with bimaxillary protrusion received subapical osteotomy. 3dMD photos were taken preoperative 1-3 days and at least 6 months after operation to obtain three-dimensional facial images. The postoperative soft tissue changes of three-dimensional landmarks, line space and angles were measured with the use of Geomagic Studio 2013, and three-dimensional deviation analysis was applied. Paired t test was performed on the measured results. P<0.05 was considered statistically significant. Results The distance of the subnasale in sagittal direction in patients with maxillary protrusion was (-10.90±18.60) mm preoperatively, (-10.05±18.62) mm (t=-7.66, P<0.001)postoperatively, and setback of (0.85±1.00) mm; Labrale superius was (-15.18±18.67) mm preoperatively, (-11.92±18.9) mm postoperatively, and setback of (3.26±1.40) mm. Preoperative nasal width was (37.32±2.32) mm, postoperative for (38.08±2.32) mm (t=-4.85, P<0.001)and increased by (0.76±1.47) mm.The lip width was (49.17±3.54) mm before surgery and (47.68±3.74) mm (t=5.77, P<0.001)after surgery (t=5.77, P<0.001), decreased by (1.49±2.42) mm. Philtrum length was (15.20±2.32) mm preoperatively and (15.78±2.17) mm (t=-4.70, P<0.001)postoperatively, increased by (0.58±1.16) mm; The nasolabial angle was 101.98°±9.34° before surgery and 109.05°±8.59° (t=-12.36, P<0.001)after surgery, increased by 6.99°±5.35°. The three-dimensional deviation analysis result showed that the soft tissue in the parasnasal area was moved forward (1.54±0.73) mm. Conclusions 3dMD can reflect the three-dimensional soft tissues changes after orthognathic surgery directly and accurately. After maxillary setback, the nasal base and upper lip of patients were significantly retrograded, and the paranasal area appeared forward, accompanied by increase in the nasolabial angle, lengthening of the philtrum length, vermillion length decrease, increase in nasal width and decrease in lip width. Key words: Orthodontic surgery; Maxillary protrusion; Soft tissue; Changes, three-dimensional; Deviation; Nasolabial region