Paolo Gargiulo and Guðmundur Á Björnsson
Computer modelling techniques and Rapid Prototyping (RP) technologies can be used to enhance applied medicine. This paper decribe the use of these methods to develop computer and physical models which are used to plan and support different surgical treatments such as complex fractures, tumours, maxilla traumas and malformations. This present work reviews the use of segmentation techniques and modelling for planning maxilla facial surgery and particularly to support the treatment of retrognathia which is a malformation where the maxilla or the mandible is further posterior than normal. The surgical process in use to correct this malformation is called distraction osteogenesis. It involves gradual, controlled displacement of surgically created fractures which results in simultaneous expansion of soft tissue and bone volume. The procedure of mandibular osteogenic distraction involves sectioning cortical bone at the site of distraction. The distraction device (the distractor) is mounted on either side of the jaw. The distractor either may be attached directly to the bone or may be partially tooth borne. Gradual distraction is then performed at a rate of 1-2 mm/day, which is done incrementally. Distractors, for intraoral use, have been developed to eliminate extra oral scars. It is complicated and frustrating to position and manipulate these devices during surgery.
The use of rapid prototyped models makes the operation easier and more accurate; indeed it is possible to adjust the distractor on the physical model and use the device directly on the patient after sterilization. Moreover pre operative preparation reduce the possibility of damaging the nerve canal during osteosynthesis since the direction of distraction is decided on the model.