Accuracy study of rapid prototyping processes applied in craniofacials biomodels

Objectives:The purpose of this study is to determinate the accuracy of the rapid prototyping biomodels using two different processes, the Selective Laser Sintering (SLS) and the Three Dimensional Printer (3DP), to verify the validity of these processes to be used as therapeutic assistance. Methods:Eight metal points were positioned at a dry skull mandible as measurements points. This mandible was submitted in a multislice computerized tomography (CT) exam, with spiral scan, 120 kV, 60 mA, 1 mm slice thickness for data acquisition. Digital measurements were made by means of two different Medical Image processing systems, Analyze (Mayo Clinic, U.S.A.) and InVesalius (CenPRA, Brazil). Two biomodels were built in two different rapid prototyping technologies,SLS and 3DP. Manual measurements, with millimetric instrument, were obtained from the mandible and the prototypes. The five groups of measurements were classified as: I – Mandible; II – Analyze; III – InVesalius; IV – SLS prototype and V – 3DP prototype. These measurements were calculated, compared and the errors, statistically analyzed. Results: The obtained errors in linear measurements between two points, compared with the mandible, was not higher than 5%, counting all groups. Comparing the medical systems with the mandible, we found 1,35% for Analyze and 1,69% for InVesalius, as the average deviation from gold standard. The prototypes had average alteration of 2,29% for SLS process and 2,41% for 3DP process, and each aggregate step increase the distortion. Conclusions: The use of prototype biomodels based on data from CT is an available technology, with clinical applications, reproducing the structures of interest with good accuracy.