Accuracy of Digitizing Master Impressions for Complete Denture Master Casts

PURPOSE: To investigate the trueness of digitized conventional impressions for data acquisition and to explore qualitative clinical limitations in the discussion. This study evaluated (a) the discrepancies of digitized impression scans captured by intraoral (IOS-IMP) and desktop scanners (LAB-IMP) compared to digitized stone cast (LS-MOD), and (b) the discrepancy of the various anatomical landmarks (peripheral, ridge, postdam, and palatal vault) between the two methods. MATERIALS AND METHODS: A total of 20 conventional bordermolded impressions of maxillary edentulous ridges were digitized using intraoral and desktop scanners. The impressions were poured and casts digitized using a desktop scanner. The root mean square (RMS) difference was determined by superimposing the intraoral scan and the desktop scan onto the digitized master cast. Additionally, results of different landmarks were analyzed. RESULTS: Paired t tests, Wilcoxon tests, Kruskal- Wallis tests, and post hoc tests were used. The mean RMS for overall LS-IMP (38.90 ± 7.67 μm) was significantly different compared to the overall IOS-IMP (75.11 ± 22.37 μm; P < .01). Within the desktop scanner group, deviations between peripheral and both palatal vault and postdam were significantly different. CONCLUSIONS: Within the limitations of this in vitro study, significant differences were found between the various landmark areas when using a desktop scanner to digitize a master cast. However, digitizing a master cast using a desktop scanner is more accurate than using an intraoral scanner.