title: Digital vs. conventional full-arch implant impressions: a comparative study.
abstract: OBJECTIVE
  To test whether or not digital full-arch implant impressions with two different intra-oral scanners (CEREC Omnicam and True Definition) have the same accuracy as conventional ones. The hypothesis was that the splinted open-tray impressions would be more accurate than digital full-arch impressions.
  
  
  METHODS
  A stone master cast representing an edentulous mandible using five internal connection implant analogs (Straumann Bone Level RC, Basel, Switzerland) was fabricated. The three median implants were parallel to each other, the far left implant had 10°, and the far right had 15° distal angulation. A splinted open-tray technique was used for the conventional polyether impressions (n = 10) for Group 1. Digital impressions (n = 10) were taken with two intra-oral optical scanners (CEREC Omnicam and 3M True Definition) after connecting polymer scan bodies to the master cast for groups 2 and 3. Master cast and conventional impression test casts were digitized with a high-resolution reference scanner (Activity 880 scanner; Smart Optics, Bochum, Germany) to obtain digital files. Standard tessellation language (STL) datasets from the three test groups of digital and conventional impressions were superimposed with the STL dataset from the master cast to assess the 3D deviations. Deviations were recorded as root-mean-square error. To compare the master cast with conventional and digital impressions at the implant level, Welch's F-test was used together with Games-Howell post hoc test.
  
  
  RESULTS
  Group I had a mean value of 167.93 μm (SD 50.37); Group II (Omnicam) had a mean value of 46.41 μm (SD 7.34); Group III (True Definition) had a mean value of 19.32 μm (SD 2.77). Welch's F-test was used together with the Games-Howell test for post hoc comparisons. Welch's F-test showed a significant difference between the groups (P < 0.001). The Games-Howell test showed statistically significant 3D deviations for all three groups (P < 0.001).
  
  
  CONCLUSIONS
  Full-arch digital implant impressions using True Definition scanner and Omnicam were significantly more accurate than the conventional impressions with the splinted open-tray technique. Additionally, the digital impressions with the True Definition scanner had significantly less 3D deviations when compared with the Omnicam.
authors.affiliation: Division of Postgraduate Prosthodontics, Tufts University School of Dental Medicine, Boston, MA, USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Amin
authors.affiliation: Division of Postgraduate Prosthodontics, Tufts University School of Dental Medicine, Boston, MA, USA.
authors.forename: Hans Peter
authors.initials: HP
authors.lastname: Weber
authors.affiliation: Department of Public Health and Community Service, Tufts University School of Dental Medicine, Boston, MA, USA.
authors.forename: Matthew
authors.initials: M
authors.lastname: Finkelman
authors.affiliation: Division of Postgraduate Prosthodontics, Tufts University School of Dental Medicine, Boston, MA, USA.
authors.forename: Khaled
authors.initials: K
authors.lastname: El Rafie
authors.affiliation: Division of Postgraduate Prosthodontics, Tufts University School of Dental Medicine, Boston, MA, USA.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Kudara
authors.affiliation: Division of Postgraduate Prosthodontics, Tufts University School of Dental Medicine, Boston, MA, USA.
authors.forename: Panos
authors.initials: P
authors.lastname: Papaspyridakos
mesh_terms: D017076:Computer-Aided Design; D003724:Dental Arch / Q000033:anatomy & histology*; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D003761:Dental Impression Technique / Q000295:instrumentation; D006801:Humans; D021621:Imaging, Three-Dimensional; D003765:Models, Dental
chemical_list: D015921:Dental Implants
keywords: dental implants; digital dentistry; digital implant impressions; edentulous; full-arch implant impressions