title: A comparison of the precision of three-dimensional images acquired by 2 digital intraoral scanners: effects of tooth irregularity and scanning direction.
abstract: OBJECTIVE
  The purpose of this study was to compare the precision of three-dimensional (3D) images acquired using iTero® (Align Technology Inc., San Jose, CA, USA) and Trios® (3Shape Dental Systems, Copenhagen, Denmark) digital intraoral scanners, and to evaluate the effects of the severity of tooth irregularities and scanning sequence on precision.
  
  
  METHODS
  Dental arch models were fabricated with differing degrees of tooth irregularity and divided into 2 groups based on scanning sequence. To assess their precision, images were superimposed and an optimized superimposition algorithm was employed to measure any 3D deviation. The t-test, paired t-test, and one-way ANOVA were performed (p < 0.05) for statistical analysis.
  
  
  RESULTS
  The iTero® and Trios® systems showed no statistically significant difference in precision among models with differing degrees of tooth irregularity. However, there were statistically significant differences in the precision of the 2 scanners when the starting points of scanning were different. The iTero® scanner (mean deviation, 29.84 ± 12.08 µm) proved to be less precise than the Trios® scanner (22.17 ± 4.47 µm).
  
  
  CONCLUSIONS
  The precision of 3D images differed according to the degree of tooth irregularity, scanning sequence, and scanner type. However, from a clinical standpoint, both scanners were highly accurate regardless of the degree of tooth irregularity.
authors.affiliation: Department of Orthodontics, Graduate School of Clinical Dentistry, Ewha Womans University, Seoul, Korea.
authors.forename: Ji-Won
authors.initials: JW
authors.lastname: Anh
authors.affiliation: Department of Prosthodontics and Dental Research Institute, Seoul National University Gwanak Dental Hospital, Seoul, Korea.
authors.forename: Ji-Man
authors.initials: JM
authors.lastname: Park
authors.affiliation: Department of Orthodontics, Graduate School of Clinical Dentistry, Ewha Womans University, Seoul, Korea.
authors.forename: Youn-Sic
authors.initials: YS
authors.lastname: Chun
authors.affiliation: Department of Pediatric Dentistry, Graduate School of Clinical Dentistry, Ewha Womans University, Seoul, Korea.
authors.forename: Miae
authors.initials: M
authors.lastname: Kim
authors.affiliation: Department of Orthodontics, Graduate School of Clinical Dentistry, Ewha Womans University, Seoul, Korea.
authors.forename: Minji
authors.initials: M
authors.lastname: Kim
keywords: Dental cast analysis; Digital models; Three-dimensional diagnosis and treatment planning; Three-dimensional scanner