The effect of different scanning protocols on precision and trueness of intraoral scanning: A pilot trial

Background: The aim of this study was to investigate how different scanning protocols affect the accuracy (trueness and precision) of intraoral scanning of complete arches with implant cylinders. Material and Methods: A master model was designed with five cylinders. One scanner, TRIOS2 (3shape), was used to scan the model with four different scan protocols: ROCK (wavelike scanning in a pendulum movement), ZIG-ZAG (wavelike scanning technique), OBP (occlusal, buccal, and palatal), and OWBP (occlusal, wiggling, buccal, and palatal). A total of 30 scans were performed using each of the four protocols. The master model was digitized with an industrial ISO-certified ATOS scanner. GOM inspect software was used to compare the scans to the master model and evaluate any deviation between the scan protocols and the master model. The data was analyzed using the One Sample t-test (p=0,05). Results: The precision (standard deviation) ranged from 23-83μm for protocol ROCK, 22-147μm for ZIGZAG, 21-170μm for OBP, and 23-116μm for OWBP. The trueness (mean deviation from master model) was 5-41μm for ROCK, 7-97μm for ZIGZAG, -21-29μm for OBP, and 1-24μm for OWBP. All protocols showed statistically significant differences to the master model in multiple distances, except OWBP, which had a single significant difference in comparison to the master model. Conclusions: Protocol OWBP has a higher trueness than other tested protocols. All tested protocols have higher trueness and precision when scanning smaller distances than inter-arch measurement. Clinical significance;The trueness and precision of intraoral scanning is generally better in smaller spans due to less deviation. The protocol OWBP, that is recommended by the manufacturer, has the least deviating trueness in comparison to the master model.