Table 2.

Selected articles.

Study	Title of the article	Description of the methodology	Search strategy
Dutton et al. [10]	The effect different substrates have on the trueness and precision of eight different intraoral scanners	A custom model, used as the reference standard, was fabricated with teeth composed of different dental materials; the reference standard scan was obtained using a three-dimensional (3D) optical scanner, the ATOS III; experimental scans were obtained using eight different IOS and operated by experienced clinicians using the manufacturer's recommended scanning strategy; a comprehensive metrology program, Geomagic Control X, was used to compare the reference standard scan with the experimental scans	intraoral scaner + orthodontics + precision + accuracy
Bocklet et al. [9]	Effect of scan substrates on accuracy of 7 intraoral digital impression systems using human maxilla model	Seven digital intraoral impression systems were used to scan a freshly harvested human maxilla; the maxilla contained several teeth restored with amalgam and composite, as well as unrestored teeth characterized by enamel; also, three teeth were prepared for full-coverage restorations to expose natural dentin; an industrial-grade metrology software program allowed 3D overlay and dimensional computation compared deviations of the complete arch and its substrates on the test model from the reference model	intraoral scanner + orthodontics + precision + accuracy AND intraoral scanner + orthodontics
Lim et al. [11]	Comparison of digital intraoral scanner reproducibility and image trueness considering repetitive experience	Twenty dental hygienists scanned 10 times his/her one assigned patient with Trios and iTero scanners, the superimposition of each patient was compared with, and Precision was calculated as the mean deviation among all superimposition combinations from the 10 scanned data sets of each learner [n = 10C2 = 45]; trueness was evaluated by superimposing the 10 consecutive intraoral scan data onto the impression scan data from each patient's rubber impression body (n = 10)	intraoral scanner + orthodontics + precision + accuracy AND intraoral scanner + orthodontics
Flügge et al. [12]	Precision of intraoral digital dental impressions with iTero and extraoral digitization with the iTero and a model scanner	One patient was scanned 10 times with iTero scanner and had impression taken (intraoral scan, group 1); next, his stone cast was scanned 10 times with iTero, group 2, and 10 times with extraoral model scanner, group 3	intraoral scanner + orthodontics + precision + accuracy
Luqmani et al. [13]	A comparison of conventional vs. automated digital Peer Assessment Rating scoring using the Carestream 3600 scanner and CS Model + software system: a randomized controlled trial	The sample consisted of 67 patients; mean age 15.03 (range 11–37) years; sixty-seven patients underwent alginate impression-taking and intraoral scanning (CS 3600; Carestream Dental, Stuttgart, Germany) at a single appointment in a randomized order; for each patient, a weighted PAR score was calculated manually by a calibrated examiner using study models and a PAR ruler (conventional group) and automatically using Carestream Dental CS Model + software and data from scanned study models (indirect digital group) or intraoral scans (direct digital group); all procedures were timed, and each patient completed a binary questionnaire relating to their experience	intraoral scanner + orthodontics
Winkler and Gkantidis [14]	Trueness and precision of intraoral scanners in the maxillary dental arch: an in vivo analysis	In 12 subjects, we evaluate the trueness and precision of two widely used intraoral scanners (TRIOS 3, 3Shape, and CS 3600, Carestream), using an industrial scanner (Artec Space Spider) as a reference; trueness of the intraoral scans was analyzed by measuring their distance from the reference scan, in the upper buccal front area; precision was tested through the distance of repeated scans regarding the whole dental arch, following superimpositions in the buccal front and in the whole dental arch area	intraoral scanner + orthodontics
Sun et al. [5]	Reproducibility of an intraoral scanner: a comparison between in vivo and ex vivo scans	Twenty adults with no missing teeth except for third molars were included in the study; alginate impressions were taken, and plaster models were made from the impressions; each subject underwent full-arch intraoral scanning twice with a TRIOS scanner (3Shape, Copenhagen, Denmark) at an interval of 2 weeks, and the plaster models were scanned at the same interval with the same scanner; the first images of each scan were superimposed on the second scanned images using surface-based registration; in each case, the differences between the 2 scanned images were evaluated with color mapping; the reproducibility between the in vivo and ex vivo scans was compared using independent t tests and Bland–Altman analysis	intraoral scanner + orthodontics
Deferm et al. [8]	Validation of 3D documentation of palatal soft tissue shape, color, and irregularity with intraoral scanning	Intraoral scans of ten participants' upper dentition and palate were acquired with the TRIOS® 3D intraoral scanner by two observers; conventional impressions were taken and digitized as a gold standard; the resulting surface models were aligned using an Iterative Closest Point approach; the absolute distance measurements between the intraoral models and the digitized impression were used to quantify the trueness and precision of intraoral scanning; the mean color of the palatal soft tissue was extracted in HSV (hue, saturation, and value) format to establish the color precision; finally, the mean curvature of the surface models was calculated and used for surface irregularity	intraoral scanner + orthodontics
Camardella et al. [7]	Accuracy and reproducibility of measurements on plaster models and digital models created using an intraoral scanner	This study included impressions of 28 volunteers; alginate impressions were used to make plaster models, and each volunteers' dentition was scanned with a TRIOS Color intraoral scanner; two examiners performed measurements on the plaster models using a digital caliper and measured the digital models using Ortho Analyzer software; the examiners measured 52 distances, including tooth diameter and height, overjet, overbite, intercanine, and intermolar distances, and the sagittal relationship; the paired t test was used to assess intraexaminer performance and measurement accuracy of the two examiners for both plaster and digital models; the level of clinically relevant differences between the measurements according to the threshold used was evaluated, and a formula was applied to calculate the chance of finding clinically relevant errors on measurements on plaster and digital models	intraoral scaner + orthodontics
Zhang et al. [6]	Validity of Intraoral Scans Compared with Plaster Models: An In Vivo Comparison of Dental Measurements and 3D Surface Analysis	Two types of dental models (intraoral scan and plaster model) of 20 subjects were included in this study; the subjects had impressions taken of their teeth and made as a plaster model; in addition, their mouths were scanned with the intraoral scanner, and the scans were converted into digital models; eight transverse and 16 anteroposterior measurements, 24 tooth heights, and widths were recorded on the plaster models with a digital caliper and on the intraoral scan with 3D reverse engineering software	intraoral scanner + orthodontics
Schmidt et al. [15]	Accuracy of Digital and Conventional Full-Arch Impressions in Patients: An Update	Trueness/precision of four intraoral scanners was assessed in five patients versus conventional impressions	intraoral scanner + precision + accuracy
Resende et al. [16]	Influence of operator experience, scanner type, and scan size on 3D scans	Trueness and precision of scans performed by 3 professionals with different levels of experience by using 2 IOSs were evaluated	intraoral scanner + precision + accuracy
Sami et al. [17]	An in vitro 3D evaluation of the accuracy of 4 intraoral optical scanners on a 6-implant model	Four IOSs scanned a 6-implant model each five times, and the trueness and precision were assessed afterwards	intraoral scanner + precision + accuracy