Reliability and validity of intraoral and extraoral scanners.
BACKGROUND
This study evaluated the reliability and validity of one extraoral [Ortho Insight 3D™ (Motionview Software, Hixson, TN/USA)] and two intraoral [ITero™ (Align Technologies, San Jose, CA/USA) and Lythos™ (Ormco Corp., Orange, CA/USA)] scanners.


METHODS
Fifteen dry human mandibles were scanned twice with each of the scanners, and digital models were generated. Five measurements were made on the dry mandibles and on each of the generated models, including intermolar width, intercanine width, posterior arch length, premolar crown diameter, and canine height. Systematic and random errors were evaluated based on replicate analyses. Differences were assessed using paired Student's t tests.


RESULTS
Replicate analyses showed statistically significant systematic errors for only one measure (intermolar width measured from Ortho Insight 3D scans). Measurements taken from all three scanners were highly reliable, with intraclass correlations ranging from .926 to .999. Method errors were all less than 0.25 mm (averaged ≈ 0.12 mm). Posterior arch length and canine height were significantly smaller when measured on the Ortho Insight 3D scans than when measured on the dry mandibles and significantly smaller than when measured from the ITero and Lythos models.


CONCLUSIONS
While all three scanners produced reliable measures, Ortho Insight 3D systematically underestimated arch length and canine height.
Department of Orthodontics, Texas A&M University Baylor College of Dentistry, 3302 Gaston Avenue, 75246, Dallas, TX, USA.
Helder B
HB
Jacob
Department of Orthodontics, Texas A&M University Baylor College of Dentistry, 3302 Gaston Avenue, 75246, Dallas, TX, USA.
Graydon D
GD
Wyatt
Department of Orthodontics, Texas A&M University Baylor College of Dentistry, 3302 Gaston Avenue, 75246, Dallas, TX, USA. phbuschang@bcd.tamhsc.edu.
Peter H
PH
Buschang
D000328:Adult; D001641:Bicuspid / Q000033:anatomy & histology; D002508:Cephalometry / Q000706:statistics & numerical data; D017076:Computer-Aided Design / Q000295:instrumentation* / Q000706:statistics & numerical data; D003481:Cuspid / Q000033:anatomy & histology; D003724:Dental Arch / Q000033:anatomy & histology; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000706:statistics & numerical data; D021621:Imaging, Three-Dimensional / Q000706:statistics & numerical data; D008334:Mandible / Q000033:anatomy & histology*; D008953:Models, Anatomic; D008963:Molar / Q000033:anatomy & histology; D015588:Observer Variation; D009811:Odontometry / Q000706:statistics & numerical data; D061848:Optical Imaging / Q000295:instrumentation* / Q000706:statistics & numerical data; D015203:Reproducibility of Results; D019228:Tooth Crown / Q000033:anatomy & histology