Accuracy of full-arch digital impressions: an in vitro and in vivo comparison

Objectives Comparison of full-arch digital impressions to conventional impressions in vitro and in vivo. Materials and methods A straight metal bar was fixed between the second upper molars as a reference structure in the mouth of a voluntary patient and a corresponding polymer model. The following digitalization methods were applied: (1) the maxilla was digitized in vivo 12 times with the iTero Element (P-SCAN); (2) the maxilla was captured in vivo 12 times by conventional impression and the impression was digitized by a desktop scanner (P-IMP); (3) the impressions were poured and the 12 referring gypsum master-casts were scanned with the same desktop scanner (P-CAST); (4) the polymer model was digitized in vitro 12 times with the iTero Element (M-SCAN); (5) the polymer model was captured in vitro 12 times by conventional impression and the impression was digitized by a desktop scanner (M-IMP); (6) the impressions were poured and the 12 referring gypsum master-casts were scanned with the same desktop scanner (M-CAST). Datasets were exported and metrically analyzed (Geomagic Control X) to determine three-dimensional length aberration and angular distortion versus the reference structure. Mann-Whitney U test was implemented to detect differences (p < 0.05). Results For multiple accuracy parameters, P-SCAN and M-SCAN showed similar or superior results compared to the other digitalization methods. The following length deviations were found: M-SCAN (- 55 to 80 mu m), M-IMP (110 to 329 mu m), M-CAST (88 to 178 mu m), P-SCAN (- 67 to 76 mu m), P-IMP (125-320 mu m), and P-CAST (92-285 mu m). Conclusions Within the limitations of this study, the iTero-scan seems to be a valid alternative to conventional impressions for full arches.