title: Changes of lip morphology following mandibular setback surgery using 3D cone-beam computed tomography images.
abstract: BACKGROUND
  The aims of this study are to evaluate the lip morphology and change of lip commissure after mandibular setback surgery (MSS) for class III patients and analyze association between the amount of mandibular setback and change of lip morphology.
  
  
  METHODS
  The samples consisted of 14 class III patients treated with MSS using bilateral sagittal split ramus osteotomy. Lateral cephalogram and cone-beam CT were taken before and about 6 months after MSS. Changes in landmarks and variables were measured with 3D software program Ondemand™. Paired and independentttests were performed for statistical analysis.
  
  
  RESULTS
  Landmarks in the mouth corner (cheilion, Ch) moved backward and downward (p< .005,p< .01). However, cheilion width was not statistically significantly changed. Landmark in labrale superius (Ls) was not altered significantly. Upper lip prominence angle (ChRt-Ls-ChLt °) became acute. Landmarks in stomion (Stm), labrale inferius (Li) moved backward (p< .005,p <.001). Lower lip prominence angle (ChRt-Li-ChLt °) became obtuse (p< .001). Height of the upper and lower lips was not altered significantly. Length of the upper lip vermilion was increased (p=< 0.01), and length of the lower lip vermilion was decreased (p< .05). Lip area on frontal view was not statistically significantly changed, but the upper lip area on lateral view was increased and change of the lower lip area decreased (p> .05,p< .005). On lateral view, upper lip prominent point (UP) moved downward and stomion moved backward and upward and the angle of Ls-UP-Stm (°) was decreased. Lower lip prominent point (LP) moved backward and downward, and the angle of Stm-LP-Li (°) was increased. Li moved backward. Finally, landmarks in the lower incisor tip (L1) moved backward and upward, but stomion moved downward. After surgery, lower incisor tip (L1) was positioned more superiorly than stomion (p< .05). There were significant associations between horizontal soft tissue and corresponding hard tissue. The posterior movement of L1 was related to statistically significantly about backward and downward movement of cheilion.
  
  
  CONCLUSIONS
  The lip morphology of patients with dento-skeletal class III malocclusion shows a significant improvement after orthognathic surgery. Three-dimensional lip morphology changes in class III patients after MSS exhibited that cheilion moved backward and downward, upper lip projection angle became acute, lower lip projection angle became obtuse, change of upper lip area on lateral view was increased, change of lower lip area decreased, and morphology of lower lip was protruding. L1 was concerned with the lip tissue change in statistically significant way.
authors: Department of Oral and Maxillofacial Surgery, College of Dentistry and Dental Hospital, Wonkwang University, Iksan, South Korea.
authors: Seung Jae
authors: SJ
authors: Paek
authors: Department of Oral and Maxillofacial Surgery, College of Dentistry and Dental Hospital, Wonkwang University, Iksan, South Korea.
authors: Ji Yong
authors: JY
authors: Yoo
authors: Department of Oral and Maxillofacial Surgery, College of Dentistry and Dental Hospital, Wonkwang University, Iksan, South Korea.
authors: Jang Won
authors: JW
authors: Lee
authors: Department of Oral and Maxillofacial Surgery, Wonkwang Dental Research Institute, College of Dentistry, Wonkwang University, 460, Iksan-daero, Iksan, Jeollabuk-do 570-749 South Korea.
authors: Won-Jong
authors: WJ
authors: Park
authors: Department of Oral and Maxillofacial Surgery, Wonkwang Dental Research Institute, College of Dentistry, Wonkwang University, 460, Iksan-daero, Iksan, Jeollabuk-do 570-749 South Korea.
authors: Young Deok
authors: YD
authors: Chee
authors: Department of Oral and Maxillofacial Surgery, Wonkwang Dental Research Institute, College of Dentistry, Wonkwang University, 460, Iksan-daero, Iksan, Jeollabuk-do 570-749 South Korea.
authors: Moon Gi
authors: MG
authors: Choi
authors: Department of Oral and Maxillofacial Surgery, Wonkwang Dental Research Institute, College of Dentistry, Wonkwang University, 460, Iksan-daero, Iksan, Jeollabuk-do 570-749 South Korea.
authors: Eun Joo
authors: EJ
authors: Choi
authors: Department of Oral and Maxillofacial Surgery, Wonkwang Dental Research Institute, College of Dentistry, Wonkwang University, 460, Iksan-daero, Iksan, Jeollabuk-do 570-749 South Korea.
authors: Kyung-Hwan
authors: KH
authors: Kwon
keywords: Cheilion; Class III malocclusion; Lip morphology; Mandibular setback surgery; Three-dimensional evaluation