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. Materials and 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; B9, 6.7 mm; Pog9, 6.7 mm; Me9, 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 (B9-Me9) was decreased because of backward and upward movement of Me9 (3.1 mm, P<.001). Although upper lip projection angle and Stm-transverse projection angle became acute (ChRt-Ls-ChLt, 5.7° Ch Rt-Stm-ChLt, 6.4°, both P, <.001) because of the greater backward movement of Ch than Stm, lower lip projection angle and Stm-vertical projection angle became obtuse (ChRt-Li-ChLt, 10.8°; Ls- Stm-Li, 23.5°, 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

A three-dimensional analysis of soft and hard tissue changes after a mandibular setback surgery

This paper is concerned with a three-dimensional (3D) analysis on soft and hard tissue changes after mandibular setback surgery. For comparing with previous two-dimensional (2D) cephalometric data,we proposed a three-dimensional registration and analysis method based on the cephalometric knowledge. The 3D changes of bone, soft tissue and the ratio of soft tissue to bony movement were investigated in eight skeletal class III mandibular prognathism patients. CT scans of each patient were taken at pre- and post-operative states. Each scan was registered to a universal 3D coordinate system defined by cephalometric landmarks. A grid, parallel to the coronal plane,was also designed for the comparison of the changes. The bone and soft tissue was intersected by the projected line from each point on the grid. The coordinate values of intersected point were measured and compared between the pre- and post-operative models. In addition, the reproducibility of the universal coordinate system and the grid was evaluated. The facial surface changes after setback surgery occurred not only in the mandible but also in the mouth corner region. The soft tissue changes of the mandible were measured relatively by the proportional ratios to the bone changes. The ratios at the mid-sagittal plane were 77–102% (p < 0.05). The ratios at all other sagittal planes had similar patterns to the mid-sagittal plane with decreased values. All the results conformed to the previous 2D based clinical knowledge and instinct of orthodontists. It is expected that the proposed approachwould be applicable to other oral and maxillofacial surgeries as well as plastic surgeries.This study was supported by grant No. R01-2006-000-11244-0 from the Basic Research Program of the Korea Science & Engineering Foundation

Dreidimensionale Veränderung der Morphologie des Gesichtes während kieferorthopädisch-kieferchirurgischer Therapie

Die vorliegende Studie berichtet über die dreidimensionale optische Vermessung der prä- und postoperativen Gesichtsoberfläche von Patienten mit kieferorthopätisch-kieferchirurgischer Therapie. Das mobile optische 3D-Messsystem Gscan realisiert die Erfassung von Form und Farbe des Gesichtes. Dreidimensionale Weichteilveränderungen werden mit dem Ausmaß der Umstellungsosteotomie der Mandibula nach anterior und posterior anhand der Messwerte der Modelloperation verglichen. Es können die Patientengruppen Unterkiefervorverlagerung, 18 Patienten, und Unterkieferrückverlagerung, 17 Patienten, spezifiziert werden. Die dreidimensionalen Weichteilveränderungen werden über arbkodierte 3D-Differenzbilder der Patienten ermittelt. Im Ergebnis zeigt sich, dass die Weichgewebe der skelettalen Verlagerung der Mandibula in geringerem Ausmaß folgen, wobei sich statistisch signi kante Weichteilveränderungen deutlich im mandibulären Bereich, vor allem an den Weichteilreferenzpunkten Sublabiale, Pogonion und Menton, abzeichnen. Sie betragen bei Unterkiefervorverlagerung 58-69% und bei Unterkieferrückverlagerung 77-90%. Des Weiteren werden Veränderungen des Gesichtstyps nach A. M. Schwarz der untersuchten Patienten bestimmt. Die vorgelegte Pilotstudie belegt, dass der Gscan ein geeignetes Instrument zur dreidimensionalen Digitalisierung des Gesichtes ist, da er dieses berührungslos, nicht-invasiv und ohne ionisierende Strahlung erfasst. Insbesondere lassen sich relative dreidimensionale Weichteilveränderungen nach monognathen Dysgnathieoperationen im Unterkiefer mit Hilfe von Gscan-Aufnahmen graphisch detailliert aufzeigen