Stability of soft tissue profile after mandibular setback in sagittal split osteotomies: a longitudinal and long-term follow-up study.
OBJECTIVE
The aim of the study was to conduct a long-term prospective follow-up on the stability of soft tissues after bilateral sagittal split osteotomy (BSSO) with rigid internal fixation to set back the mandible.


METHODS
Seventeen consecutive patients (6 females, 11 males) were re-examined 12.7 years (T5) after surgery. The precedent follow-ups included: before surgery (T1), 5 days (T2) after surgery, 6.6 months (T3) after surgery, and 14.4 months after (T4) surgery. Lateral cephalograms were traced by hand, digitized, and evaluated with the Dentofacial Planner program (Dentofacial Software, Toronto, Canada). The x-axis for the system of coordinates ran through Sella (point 0) and the line NSL -7 degrees.


RESULTS
The net effect of the soft tissue chin (soft tissue pogonion) was 79% of the setback at pogonion. At the lower lip (labrale inferior) it was 100% of the setback at lower incisor position. Point B' followed point B to 99%. Labrale inferior and menton' also showed a significant backward, as well as a downward, movement (T5 to T2). Gender correlated significantly (P = .004) with the anterior displacement of point B' and pogonion' (P = .012). The soft tissue relapse 12.7 years after BSSO setback surgery at point B' was 3% and 13% at pogonion'.


CONCLUSIONS
Among the reasons for 3-dimensional long-term soft tissue changes of shape, the surgical technique, the normal process of human aging, the initial growth direction, and remodeling processes must be considered. Growth direction positively influenced the long-term outcome of setback surgery in female compared with male patients because further posterior movement of the mandibular soft tissue occurred.
Joss
Christof Urs
CU
Department of Orthodontics, University of Geneva, Geneva, Switzerland. christof.joss@medecine.unige.ch
Vassalli
Isabella Maria
IM
Thüer
Urs Walter
UW
D000293:Adolescent; D000328:Adult; D001863:Bone Screws; D002508:Cephalometry / Q000379:methods; D002680:Chin / Q000473:pathology; D005145:Face / Q000033:anatomy & histology*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D007180:Incisor / Q000473:pathology; D016268:Internal Fixators; D008046:Lip / Q000473:pathology; D008137:Longitudinal Studies; D008297:Male; D008313:Malocclusion, Angle Class III / Q000601:surgery; D008334:Mandible / Q000473:pathology / Q000601:surgery*; D010027:Osteotomy / Q000295:instrumentation / Q000379:methods*; D011446:Prospective Studies; D012008:Recurrence; D012737:Sex Factors; D016896:Treatment Outcome