Effect of pulp chamber depth on the accuracy of endocrown scans made with different intraoral scanners versus an industrial scanner: An in vitro study

Statement of problem. The accuracy of intraoral scanners (IOSs) has been evaluated. However, testing their performance when scanning deep endocrown preparations is lacking. Purpose. The purpose of this in vitro study was to assess the effect of pulpal chamber extension depth (PCED) on scanning accuracy and to compare the accuracy of different IOSs on scanning different PCEDs. Material and methods. Six different IOSs were compared: TRIOS 3, CEREC Omnicam, CEREC Primescan, Planmeca Emerald, iTero Element2, and Virtuo Vivo. Endocrown preparations were digitally designed with a computer-aided design and computer-aided manufacturing (CAD-CAM) software program (Rhicoceros), and the PCEDs of preparations were 2, 3.5, and 5 mm. Designed preparations were milled from a polymethylmethacrylate block (Telio CAD) with a milling unit. Reference scans were obtained from an industrial scanner (ATOS), and 5 test scans of each cavity were made with 6 IOSs. All scans were converted into standard tessellation language (STL) files. The data sets obtained from the IOSs were superimposed on the reference scan to evaluate trueness and on each other within groups to determine precision by using a 3D analysis software program (Geomagic Control X). Obtained data were analyzed with 1-way ANOVA and Tukey HSD tests (alpha=.05). Results. CEREC Primescan was found to have the best trueness and precision among the evaluated IOSs (P<.05), while Planmeca Emerald was found to have the lowest trueness (P<.05). For all tested PCEDs, statistically significant differences were found among IOSs. A PCED with a 2-mm depth (18.57 +/- 4.80 mu m) showed significantly better scanning trueness than that with a 5-mm depth (23.81 +/- 6.53), while no significant differences were found between 2 and 3.5 mm (P>.05). Conclusions: Deep pulpal chamber extensions of endocrown restorations could negatively affect scanning accuracy, and scanning accuracy varies depending on the selected IOS. CEREC Primescan appears to be the best IOS choice for scanning endocrowns with deep pulpal chamber extensions.