| Sumario: | Background: Whether we are talking about digital or conventional impressions, their accuracy is essential in dental treatments. Most of the studies that assessed the "accuracy" of two models or datasets only compared them using a best-fit algorithm of 3D software. This approach only describes the discrepancy between the two models or datasets. However, it needs to provide more information on the accuracy of the impression technique itself due to the need for a proper reference. Best-fit algorithms compensate for errors throughout the jaw, minimizing mesh errors but not providing a proper reference. In order to analyze transfer accuracy in terms of trueness and precision of the method, a reference is mandatory. Therefore, a sound investigation using a proper reference under standardized conditions must address the limited amount of even partially contradictory data. Objective: The study aims to investigate the intraoral scanning system's transfer accuracy on full arch scans compared to conventional impressions. Material and methods: This study used ten mandibular artificial arches and a reference aid. The reference aid used in the study was a set of four high-precision bearing spheres positioned on the mandibular jaw's occlusal surface. These spheres were reversibly bonded with flowable composite. All models were scanned with a Dental Wings intraoral scanner, and conventional impressions were performed using a monophasic technique. The conventional impressions were cast with orthodontic dental stone. All digital and analog impressions were measured and compared with reference values. The statistical analysis was performed to assess if there is a statistical difference between reference aid and impressions. The statistical difference was set at p < 0.05. Results : The recorded results show that neither the digital nor the conventional impression was accurate along the entire dental arch length. The recorded results show that neither the digital nor the conventional impressions are accurate along the entire dental arch length. All obtained models presented statistical differences compared to references related to specific measurement points. Conclusions: Although intraoral scanners have improved over time, they still lack accuracy, especially for long-span distances. The conventional impression technique provides better results for long-span distances.
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