Accuracy of single-abutment digital cast obtained using intraoral and cast scanners

Abstract

Statement of problem. Scanners are frequently used in the fabrication of dental prostheses. However, the accuracy of these scanners is variable, and little information is available. Purpose. The purpose of this in vitro study was to compare the accuracy of cast scanners with that of intraoral scanners by using different image impression techniques. Material and methods. A poly(methyl methacrylate) master model was fabricated to replicate a maxillary first molar single-abutment tooth model. The master model was scanned with an accurate engineering scanner to obtain a true value (n=1) and with 2 intraoral scanners (CEREC Bluecam and CEREC Omnicam; n=6 each). The cast scanner scanned the master model and duplicated the dental stone cast from the master model (n=6). The trueness and precision of the data were measured using a 3-dimensional analysis program. The Kruskal-Wallis test was used to compare the different sets of scanning data, followed by a post hoc Mann-Whitney U test with a significance level modified by Bonferroni correction (alpha/6=.0083). The type 1 error level (a) was set at .05. Results. The trueness value (root mean square: mean standard deviation) was 17.5 +/- 1.8 mu m for the Bluecam, 13.8 +/- 1.4 mu m for the Omnicam, 17.4 +/- 1.7 mu m for cast scanner 1, and 12.3 +/- 0.1 mu m for cast scanner 2. The differences between the Bluecam and the cast scanner 1 and between the Omnicam and the cast scanner 2 were not statistically significant (P>.0083), but a statistically significant difference was found between all the other pairs (P<.0083). The precision of the scanners was 12.7 +/- 2.6 gm for the Bluecam, 12.5 +/- 3.7 p.m for the Omnicam, 9.2 +/- 1.2 gm for cast scanner 1, and 6.9 2.6 p.m for cast scanner 2. The differences between Bluecam and Omnicam and between Omnicam and cast scanner 1 were not statistically significant (P>.0083), but there was a statistically significant difference between all the other pairs (P<.0083). Conclusions. An Omnicam in video image impression had better trueness than a cast scanner but with a similar level of precision.