Three-dimensional evaluation of soft tissue change gradients after mandibular setback surgery in skeletal Class III malocclusion.
OBJECTIVE
To evaluate whether mandibular setback surgery (MSS) for Class III patients would produce gradients of three-dimensional (3D) soft tissue changes in the vertical and transverse aspects.


METHODS
The samples consisted of 26 Class III patients treated with MSS using bilateral sagittal split ramus osteotomy. Lateral cephalograms and 3D facial scan images were taken before and 6 months after MSS, and changes in landmarks and variables were measured using a Rapidform 2006. Paired and independent t-tests were performed for statistical analysis.


RESULTS
Landmarks in the upper lip and mouth corner (cheilion, Ch) moved backward and downward (respectively, cupid bow point, 1.0 mm and 0.3 mm, P < .001 and P < .01; alar curvature-Ch midpoint, 0.6 mm and 0.3 mm, both P < .001; Ch, 3.4 mm and 0.8 mm, both P < .001). However, landmarks in stomion (Stm), lower lip, and chin moved backward (Stm, 1.6 mm; labrale inferius [Li], 6.9 mm; LLBP, 6.9 mm; B', 6.7 mm; Pog', 6.7 mm; Me', 6.6 mm; P < .001, respectively). Width and height of upper and lower lip were not altered significantly except for a decrease of lower vermilion height (Stm-Li, 1.7 mm, P < .001). Chin height (B'-Me') was decreased because of backward and upward movement of Me' (3.1 mm, P < .001). Although upper lip projection angle and Stm-transverse projection angle became acute (Ch(Rt)-Ls-Ch(Lt), 5.7 degrees; Ch(Rt)-Stm-Ch(Lt), 6.4 degrees, both P < .001) because of the greater backward movement of Ch than Stm, lower lip projection angle and Stm-vertical projection angle became obtuse (Ch(Rt)-Li-Ch(Lt), 10.8 degrees ; Ls-Stm-Li, 23.5 degrees , both P < .001) because of the larger backward movement of Li than labrale superius (Ls).


CONCLUSIONS
Three-dimensional soft tissue changes in Class III patients after MSS exhibited increased gradients from upper lip and lower lip to chin as well as from Stm to Ch.
Lim
Yong-Kyu
YK
Department of Orthodontics, Graduate School of Clinical Dentistry, Korea University, Seoul, South Korea.
Chu
Eun-Hye
EH
Lee
Dong-Yul
DY
Yang
Il-Hyung
IH
Baek
Seung-Hak
SH
D000293:Adolescent; D000328:Adult; D002508:Cephalometry / Q000379:methods*; D002680:Chin / Q000473:pathology; D003768:Dental Occlusion, Centric; D005143:Eyelids / Q000473:pathology; D005145:Face; D005260:Female; D005500:Follow-Up Studies; D005546:Forehead / Q000473:pathology; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods*; D008046:Lip / Q000473:pathology; D008297:Male; D008313:Malocclusion, Angle Class III / Q000473:pathology / Q000601:surgery*; D008334:Mandible / Q000473:pathology / Q000601:surgery*; D055171:Nasal Cartilages / Q000473:pathology; D009666:Nose / Q000473:pathology; D056948:Orthognathic Surgical Procedures / Q000379:methods*; D010027:Osteotomy / Q000379:methods; D014716:Vertical Dimension; D055815:Young Adult