Trueness of intraoral scanners in digitizing specific locations at the margin and intaglio surfaces of intracoronal preparations

Abstract

Statement of problem. Studies evaluating the trueness of intraoral scanners (IOSs) at anatomic locations within an intracoronal preparation are lacking. Purpose. The purpose of this in vitro study was to evaluate the trueness of digital scans obtained by IOSs at the margin and intaglio surfaces of intracoronal preparations. Material and methods. Six IOSs (CEREC Omnicam, E4D, FastScan, iTero, TRIOS, Zfx IntraScan) were used to obtain digital scans of various intracoronal preparations. Standard tessellation language (STL) data sets obtained from a reference scanner and each IOS were superimposed, and the deviation of the digital casts was assessed at multiple measuring points along the margin and intaglio surfaces of each preparation. The Kruskal-Wallis test and multiple Mann -Whitney tests were used to detect differences in trueness (alpha=.05). Results. The overall median trueness values were lowest for TRIOS (23.9 mu m), followed by Zfx IntraScan (24.6 mu m), iTero (25.4 mu m), FastScan (26.1 mu m), CEREC Omnicam (26.9 mu m), and E4D (77.5 mu m). The greatest deviation was generally observed at the line angles between the preparation surfaces. The axiogingival line angle was the most error-prone location in the cavity preparations. An increased tendency to produce a more accurate impression was observed when the cavity had a greater width and more divergent walls. Conclusions. The trueness of digital scans was influenced by the type of IOS and the location within a prepared cavity. The trueness decreased at the line angles between the preparation surfaces, particularly at the axiogingival line angle. Among the tested IOSs, E4D produced the least accurate digital scans.