Objectives The integration of computer-aided design and manufacturing technologies in diagnosis, treatment planning, and fabrication of prosthetic restoration is changing the way in which prosthodontic treatment is provided to patients. The aim of this study was to compare the accuracy of three-dimensional (3D) printed casts produced from the intraoral scanner using stereolithographic (SLA) 3D printing technique, their digital replicas, and conventional stone casts. Materials and Methods In this in vitro study, a typodont of maxillary and mandibular arches with full dentate ivory teeth was used as a reference cast. The typodont was digitized using Trios 3Shape intraoral scanner to create digital casts. The digital files were converted into 3D printed physical casts using a prototyping machine that utilizes the stereolithography printing technology and photocurable polymer as printing material. Linear measurements (mesiodistal and occlusocervical) and interarch measurements (intercanine and intermolar) were made for digital and prototyped models and were compared with the original stone casts. The reference teeth were canines, first premolars and second premolars in the maxillary and mandibular arches on the right and left sides. The measurements on printed and conventional casts were done by digital caliper while on digital casts; Geomagic Qualify software was used. Statistical Analysis One-way analysis of variance (ANOVA) was used to compare measurements among groups. Results Digital casts showed significantly higher error than the other two groups in all linear and interarch measurements. The mean errors of the digital cast in occlusocervical (OC) and mesiodistal (MD) measurements (0.016 and 0.006, respectively) were higher compared with those in the other two groups (OC, 0.004 and 0.007 and MD, 0.003 and 0.005 [p < 0.0001 and p = 0.02, respectively]). Also, digital mean error in intermolar width (IMW) and intercanine width (ICW) (0.142 and 0.113, respectively) were greater than the other two groups (IMW, 0.019 and 0.008 and ICW, 0.021 and 0.011 [p < 0.0001]). However, the errors were within the acceptable clinical range. Conclusion The 3D printed casts may be considered as a substitute for stone casts with clinically acceptable accuracy that can be used in diagnosis, treatment planning, and fabrication of prosthetic restorations.

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INTRODUCTION: An accurate digital impression is essential in fabrication of fixed dental prostheses. Digital dental impressions are recorded either by intraoral or extraoral scanners. Intraoral scanners scan abutments inside oral cavity eliminating the need of fabrication of dental casts. The extraoral scanners scan physical impressions or dental casts to produce a digital model. OBJECTIVES: The aim of this study was to compare the accuracy of digital dental models produced by two different intraoral scanners in relation to the reference cast. MATERIALS AND METHODS: This in vitro study included an original typodont simulating patient's mouth. The reference typodont model was scanned by two intraoral scanners (3shape, Dental Wings) to produce digital models from both scanners. Mesiodistal (MD) and buccolingual (BL) measurements were recorded for canines, first premolars and first molars in both maxillary and mandibular jaws by same operator in the right and left sides and compared to measurements done on reference model. P values and adjusted means were calculated. Significance was set at 5%. SPSS version 22.0 was used for statistical analysis. RESULTS: There was no significant difference found between the accuracies of 3shape and Dental Wings digital models (p = 0.97) which were <0.5mm, in comparison to the reference model. Regarding the reference teeth, the canine showed the highest accuracy (p< 0.0001). CONCLUSIONS: The accuracy of digital models produced by the two intraoral scanners was similar with a minor level of discrepancies. Also, the canine showed the highest accuracy in the scanning procedure as it possess smooth surface.