THE VALUE OF STEREOLITHOGRAPHIC MODELS FOR PREOPERATIVE DIAGNOSIS OF CRANIOFACIAL DEFORMITIES AND PLANNING OF SURGICAL CORRECTIONS

The purpose of this study was to assess the importance of stereolithog raphic models (SLMs) for preoperative diagnosis and planning in cranio facial surgery and to examine whether these models offer valuable addi tional information as compared to normal CT scans and 3D CT images. Cr aniofacial SLMs of 20 patients with craniomaxillofacial pathology were made. A helical volume CT scan of the anatomic area involved delivere d the necessary data for their construction. These were built with an SLA 250 stereolithography apparatus (3D-Sysrems, Valencia, CA, USA), s teered by FORM-IT/DCS(R) software (University of Zurich, Switzerland). The stereolithography models were classified according to pathology, type of surgery and their relevance for surgical planning. Though not objectively measurable, it was beyond doubt that relevant additional i nformation for the surgeon was obtained in cases of hypertelorism, sev ere asymmetries of the neuro- and viscerocranium, complex cranial syno stoses and large skull defects. The value of these models as realistic ''duplicates'' of complex or rare dysmorphic craniofacial pathology f or the purpose of creating a didactic collection should also be emphas ized. The models proved to be less useful in cases of consolidated fra ctures of the periorbital and naso-ethmoidal complex, except where the re was major dislocation.