Evaluation of the Accuracy of Digital Impressions Obtained from Intraoral and Extraoral Dental Scanners with Different CAD/CAM Scanning Technologies: An In Vitro Study

Purpose To compare the accuracy of intraoral and extraoral scanners (IOSs and EOSs) with different scanning technologies. Material and Methods A phantom cast was used to simulate the patient's mouth. Polyether impression was made of the phantom cast and poured to fabricate stone casts. The stone casts were scanned by two IOSs (3shape Trios 3, 3S and Dental Wings, DW) and two EOSs (S600 Arti Zirkonzahn, ZK and Ceramill map 600 Amann Girrbach, AG) to obtain digital casts. Reference teeth (canines, premolar, and molars) dimensions were measured on the digital casts by Geomagic software and compared to measurements of the stone cast done by stereomicroscope. The dimensions were occluso-cervical mesio-distal, and bucco-lingual and their average was calculated. Differences between digital and stereoscopic measurements were assessed using paired t-test. Discrepancies between these measurements were calculated as differences and were compared among the four scanners using ANOVA. Results The differences among the discrepancies of the four scanners were not significant overall (p = 0.969), in premolars (p = 0.932) or molars (p = 0.069) but significant in canines (p = 0.025). The discrepancies of the EOSs were <= 0.01 mm in canines and molars. DW had the greatest discrepancy in canines and molars. Conclusions The IOSs and EOSs had similar accuracy except in canines where EOSs performed better. The accuracy of scanning is affected by the smoothness and regularity of the teeth surfaces as in case of the canine.