Accuracy of Conventional and Digital Methods of Obtaining Full-Arch Dental Impression (In Vitro Study)

Introduction The current gold standard is a conventional impression made with various impression materials and trays and results in a gypsum cast. With the development of milling and printing materials in dentistry, especially zirconia, a digital model has become increasingly important. Objectives To compare the accuracy of the conventional impression scan (CIS), gypsum cast scan (GCS), and digital impression scan (DIS) to obtain a full-arch digital model. Materials and methods A resin reference cast was fabricated. It was scanned by an extra-oral scanner to measure its accuracy as a reference scanner. Eight conventional impressions of the reference cast were taken by polyvinyl siloxane and scanned. After that, they were poured with type IV dental stones and scanned too. The reference cast was scanned by an intraoral scanner eight separate times. Digital models within each group were superimposed individually to measure precision. In addition, each model from each group was superimposed on one model from the reference scanner precision group to measure trueness. Results The reference scanner showed the highest accuracy among groups with a precision of 1.5 +/- 0.8 mu m and a trueness of 5.5 +/- 1.9 mu m (P<0.006), while precision values of gypsum cast were 8.1 +/- 1.7 mu m and trueness values were 9.3 +/- 2.6 mu m (P<0.012). Conventional impressions showed a precision of 14.06 +/- 2.01 mu m and a trueness of 16.15 +/- 2.07 mu m (P<0.012). Digital impressions were the least accurate among the groups, as precision values were 38.22 +/- 15.23 mu m and trueness values were 35.19 +/- 8.7 mu m (P<0.006). Conclusion The gypsum cast scans showed the highest accuracy, followed by the conventional impression scans, and finally the digital impression scans, with no clinical significance.