R_Bibb_Medical_Modelling_The_Application_of_Adv.pdf

162 Medical modelling
6.40 3D facial images pre-operative (left) and post-operative (right).
scanners were controlled with Multi-scan software (Cebas Computer
GmbH, Lilienthalstrasse 19, 69214 Eppelheim, Germany) and data coordinates
were saved in the Minolta Vivid fi le format (called a .vvd). The
scan data was transferred to a reverse modelling software package
(Rapidform TM 2004, INUS Technology Inc., SBC, Ludwig-Erhard-Strasse,
30-34, D-65760 Eschborn, Germany) for analysis.
6.7.4 Results
Surgical distraction of the maxilla at Le Fort 1 level was successfully completed
(Le Fort 1 is a cut across the maxilla above the roots of the teeth
but under the nose in order to separate and move the upper jaw in relation
to the rest of the skull). The distractors were activated by 7 mm on right
and left sides resulting in an equivalent advancement of the tooth-bearing
portion of the maxilla. A description of distraction osteogenesis is given in
medical explanatory note 8.2.3. Superimposition of surface scans allowed
quantifi cation of soft tissue changes (Fig. 6.41 – see Fig. 6.41 in the colour
section). Black areas indicate changes within 0.80 mm or less, which could
be attributed to the error of the technique. The blue areas demonstrate
negative changes of 0.85–2.30 mm. The red areas demonstrate positive
changes of 0.85–3.51 mm.
6.7.5 Discussion
Changes in maxillary prominence and lip relationship can be appreciated
by comparison of pre- and post-operative scans in Fig. 6.40. The magnitude