title: White light scanner-based repeatability of 3-dimensional digitizing of silicon rubber abutment teeth impressions.
abstract: OBJECTIVE
  The aim of this study was to evaluate the repeatability of the digitizing of silicon rubber impressions of abutment teeth by using a white light scanner and compare differences in repeatability between different abutment teeth types.
  
  
  METHODS
  Silicon rubber impressions of a canine, premolar, and molar tooth were each digitized 8 times using a white light scanner, and 3D surface models were created using the point clouds. The size of any discrepancy between each model and the corresponding reference tooth were measured, and the distribution of these values was analyzed by an inspection software (PowerInspect 2012, Delcamplc., Birmingham, UK). Absolute values of discrepancies were analyzed by the Kruskal-Wallis test and multiple comparisons (α=.05).
  
  
  RESULTS
  The discrepancy between the impressions for the canine, premolar, and molar teeth were 6.3 µm (95% confidence interval [CI], 5.4-7.2), 6.4 µm (95% CI, 5.3-7.6), and 8.9 µm (95% CI, 8.2-9.5), respectively. The discrepancy of the molar tooth impression was significantly higher than that of other tooth types. The largest variation (as mean [SD]) in discrepancies was seen in the premolar tooth impression scans: 26.7 µm (95% CI, 19.7-33.8); followed by canine and molar teeth impressions, 16.3 µm (95% CI, 15.3-17.3), and 14.0 µm (95% CI, 12.3-15.7), respectively.
  
  
  CONCLUSIONS
  The repeatability of the digitizing abutment teeth's silicon rubber impressions by using a white light scanner was improved compared to that with a laser scanner, showing only a low mean discrepancy between 6.3 µm and 8.9 µm, which was in an clinically acceptable range. Premolar impression with a long and narrow shape showed a significantly larger discrepancy than canine and molar impressions. Further work is needed to increase the digitizing performance of the white light scanner for deep and slender impressions.
authors.affiliation: Department of Dental Laboratory Science and Engineering, College of Health Science, Korea University, Seoul, Republic of Korea.
authors.forename: Jin-Hun
authors.initials: JH
authors.lastname: Jeon
authors.affiliation: Department of Dental Laboratory Science and Engineering, College of Health Science, Korea University, Seoul, Republic of Korea.
authors.forename: Kyung-Tak
authors.initials: KT
authors.lastname: Lee
authors.affiliation: Department of Dental Laboratory Science and Engineering, College of Health Science & Department of Public Health Sciences, Graduate School & BK21+ Program in Public Health Sciences, Korea University, Seoul, Republic of Korea.
authors.forename: Hae-Young
authors.initials: HY
authors.lastname: Kim
authors.affiliation: Department of Dental Laboratory Science and Engineering, College of Health Science, Korea University, Seoul, Republic of Korea.
authors.forename: Ji-Hwan
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Dental Laboratory Science and Engineering, College of Health Science, Korea University, Seoul, Republic of Korea.
authors.forename: Woong-Chul
authors.initials: WC
authors.lastname: Kim
keywords: 3D-surface model; Dental white light scanner; Digital impression; Repeatability