Korean J Orthod.  2021 Mar;51(2):95-104. 10.4041/kjod.2021.51.2.95.

Full-arch accuracy of five intraoral scanners:In vivo analysis of trueness and precision

• Kwon M
• Cho Y
• Kim DW
• Kim M
• Kim YJ
• Chang M

• KMID: 2513578
• DOI: http://doi.org/10.4041/kjod.2021.51.2.95

Abstract

Objective
To evaluate the trueness and precision of full-arch scans acquired using five intraoral scanners and investigate the factors associated with the dimensional accuracy of the intraoral scan data.
Methods
Nine adult participants (mean age, 34.3 ± 8.3 years) were recruited. Four zirconium spheres (Ø 6 mm) were bonded to the canines and the molars. Following acquisition of reference scans using an industrial-grade scanner, five intraoral scanners, namely i500, CS3600, Trios 3, iTero, and CEREC Omnicam, were used to scan the arches. Linear distances between the four reference spheres were automatically calculated, and linear mixed model analysis was performed to compare the trueness and precision of the intraoral scan data among the different scanners.
Results
The absolute mean trueness and precision values for all intraoral scanners were 76.6 ± 79.3 and 56.6 ± 52.4 µm, respectively. The type of scanner and the measured linear distances had significant effects on the accuracy of the intraoral scan data. With regard to trueness, errors in the intermolar dimension and the distance from the canine to the contralateral molar were greater with Omnicam than with the other scanners. With regard to precision, the error in the linear distance from the canine to the molar in the same quadrant was greater with Omnicam and CS3600 than with the other scanners.
Conclusions
The dimensional accuracy of intraoral scan data may differ significantly according to the type of scanner, with the amount of error in terms of trueness being clinically significant.

Keyword

Digital impression; Intraoral scanner; Precision; Trueness

Figure

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  Figure 1 Placement of reference spheres for the in vivo measurement of linear distances. Four reference spheres have been attached to the lingual or palatal surface of the right and left canines and the occlusal surface of the right and left first molars. Intraoral scan data are acquired for accuracy analysis.

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  Figure 2 Reference scans for in vivo analysis of trueness. Reference scans of the four spheres are acquired using an industrial-grade scanner (Solutionix C500; Medit Corp., Seoul, Korea) for in vivo analysis of trueness.

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  Figure 3 Measurement of linear distances. Linear distances between spheres are automatically calculated by matching with pre-imputed specification data. Distance 1, between reference spheres 1 and 2; Distance 2, between reference spheres 1 and 3; Distance 3, between reference spheres 1 and 4; Distance 4, between reference spheres 2 and 3; Distance 5, between reference spheres 2 and 4; Distance 6, between reference spheres 3 and 4.

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  Figure 4 Mean positive and negative errors in terms of trueness according to the scanner type (µm). Distance 1, between reference spheres 1 and 2; Distance 2, between reference spheres 1 and 3; Distance 3, between reference spheres 1 and 4; Distance 4, between reference spheres 2 and 3; Distance 5, between reference spheres 2 and 4; Distance 6, between reference spheres 3 and 4.

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  Figure 5 Mean absolute error in trueness according to the scanner type (µm). Distance 1, between reference spheres 1 and 2; Distance 2, between reference spheres 1 and 3; Distance 3, between reference spheres 1 and 4; Distance 4, between reference spheres 2 and 3; Distance 5, between reference spheres 2 and 4; Distance 6, between reference spheres 3 and 4.

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  Figure 6 Mean absolute errors in terms of the trueness (A) and precision (B) of intraoral scanners according to the measured linear distances (µm). 1, distance between reference spheres 1 and 2; 2, distance between reference spheres 1 and 3; 3 distance between reference spheres 1 and 4; 4, distance between reference spheres 2 and 3; 5, distance between reference spheres 2 and 4; 6, distance between reference spheres 3 and 4.

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