Accuracy of Intraoral Scanners vs. Conventional Impressions: Pilot Study

Objectives: The purpose of this in-vitro study was to evaluate one of the most important aspects: trueness and precision of digital models obtained by intraoral scanners when compared with the reference model, and to compare them with conventional impressions models.
Methods: A digital model was produced and printed in three dimensions (3D). It was scanned with a laboratory scanner to obtain the reference data. Then, it was scanned by three intraoral scanners: TRIOS® 3 (3SHAPE™), i500 (MEDIT™) and 3M™ TRUE DEFINITION (3M™ ESPE). Conventional impressions were followed by subsequent type IV plaster casting. Finally, laboratory scanner readings were performed. In the three-dimensional analysis program, GOM Inspect 2019, the images were submitted to the measurements proposed for the evaluation of the degree of trueness and precision of the different techniques.
Results: Concerning all the measurements, Trios 3 shows the highest trueness (46.3±52.1µm), followed by conventional impressions (49.7±54.6µm), i500 Medit (76.7±59.3µm) and 3M True Definition (91.7±70.1µm). In turn, conventional impressions are the one with the best precision (21.8±12.9µm) followed, by Trios 3 (27.0±12.2µm), 3M True Definition (36.6±23.8µm) and lastly i500 Medit (38.2±15.8µm).
Conclusions: In conclusion, digital vs. conventional systems are very close in terms of precision and trueness, but digital systems have greater advantages in clinical and laboratory use, where Trios 3 intraoral scanner showed the highest degree of accuracy (trueness and precision) in full arch readings, as well as results superior to those obtained by conventional impressions.