Detectability and reproducibility of the edge including the micro step in laboratory and intraoral scanners

Abstract

 The aim of this study was to evaluate the detectability and the reproducibility of the edge including small step.

 Specimen was Step Master, which has known dimension, and was scanned with 2 laboratory (D900 and map400) and 2 intraoral scanners (Trios3 and CS3600), each 10 times. The reference model, which has same size and steps as the specimen, was designed by CAD software. The edge of each block was designed with a right angle. Scanned model and reference model were superimposed. An analytical region on the scanned model including step of 300μm was determined. The mismatched of scanned edge region with respect to the reference model was selected, and a best-fit cylinder to data points within the selected area was designed. The radius of cylinder was calculated to evaluate the reproducibility of the edge. The number of triangles within the square area (1.0×1.0 cm²) was counted and the size of those was observed.

 All 4 scanners could detect the edge. There were significant differences of the corner radius among the 4 scanners. Our evaluation method using the corner R value has a possibility that can assess the finish line edge 3-dimensionally and quantitatively.