Evaluation of a Facial Impression Technique using a Non-contact 3-D Digitizer First Report

Abstract

The conventional facial impression technique involves inaccuracy of alginate impression material and distortion of facial surface topology due to the weight of the impression material. A non-contact three-dimensional （3-D） digitizer enables a surface configuration to be acquired in a few seconds. The aim of this study was to evaluate the conventional facial impression using a 3-D digitizer, VIVID 910. Facial impressions were taken on three volunteers with alginate and fast setting plaster, and laser surface scanning of the subject’s face was also performed by the 3-D digitizer on the same day. Cast facial models were fabricated and then laser scanned. Each morphological data was overlapped and amounts of discrepancy were analyzed on the various facial points and using data processing software. As a result, the amounts of discrepancy were found to vary depending on facial points. The discrepancy of the cheek area was greater than that of the forehead area. Those areas were compressed on the facial models, whereas the orbital area on the facial models was swollen compared to the laser scanned facial surface. In conclusion, the facial model made by the conventional facial impression technique includes area dependent size errors. The relatively thin skin area underlined by bone was more accurate than thick soft tissue area.