title: Accuracy of digital impressions of multiple dental implants: an in vitro study.
abstract: BACKGROUND
  Studies demonstrated that the accuracy of intra-oral scanners can be compared with conventional impressions for most indications. However, little is known about their applicability to take impressions of multiple implants.
  
  
  OBJECTIVE
  The aim of this study was to evaluate the accuracy of four intra-oral scanners when applied for implant impressions in the edentulous jaw.
  
  
  METHODS
  An acrylic mandibular cast containing six external connection implants (region 36, 34, 32, 42, 44 and 46) with PEEK scanbodies was scanned using four intra-oral scanners: the Lava C.O.S. and the 3M True Definition, Cerec Omnicam and 3Shape Trios. Each model was scanned 10 times with every intra-oral scanner. As a reference, a highly accurate laboratory scanner (104i, Imetric, Courgenay, Switzerland) was used. The scans were imported into metrology software (Geomagic Qualify 12) for analyses. Accuracy was measured in terms of trueness (comparing test and reference) and precision (determining the deviation between different test scans). Mann-Whitney U-test and Wilcoxon signed rank test were used to detect statistically significant differences in trueness and precision respectively.
  
  
  RESULTS
  The mean trueness was 0.112 mm for Lava COS, 0.035 mm for 3M TrueDef, 0.028 mm for Trios and 0.061 mm for Cerec Omnicam. There was no statistically significant difference between 3M TrueDef and Trios (P = 0.262). Cerec Omnicam was less accurate than 3M TrueDef (P = 0.013) and Trios (P = 0.005), but more accurate compared to Lava COS (P = 0.007). Lava COS was also less accurate compared to 3M TrueDef (P = 0.005) and Trios (P = 0.005). The mean precision was 0.066 mm for Lava COS, 0.030 mm for 3M TrueDef, 0.033 mm for Trios and 0.059 mm for Cerec Omnicam. There was no statistically significant difference between 3M TrueDef and Trios (P = 0.119). Cerec Omnicam was less accurate compared to 3M TrueDef (P < 0.001) and Trios (P < 0.001), but no difference was found with Lava COS (P = 0.169). Lava COS was also less accurate compared to 3M TrueDef (P < 0.001) and Trios (P < 0.001).
  
  
  CONCLUSIONS
  Based on the findings of this in vitro study, the 3M True Definition and Trios scanner demonstrated the highest accuracy. The Lava COS was found not suitable for taking implant impressions for a cross-arch bridge in the edentulous jaw.
authors.affiliation: Department of Periodontology, Oral Implantology, Removable and Implant Prosthetics, Dental School, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
authors.forename: Stefan
authors.initials: S
authors.lastname: Vandeweghe
authors.affiliation: Department of Periodontology, Oral Implantology, Removable and Implant Prosthetics, Dental School, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.
authors.forename: Valentin
authors.initials: V
authors.lastname: Vervack
authors.affiliation: Oral and Maxillofacial Imaging Unit, Dental School, University Hospital Ghent, Ghent, Belgium.
authors.forename: Melissa
authors.initials: M
authors.lastname: Dierens
authors.affiliation: Department of Periodontology, Oral Implantology, Removable and Implant Prosthetics, Dental School, Faculty of Medicine and Health Sciences, Ghent University, Ghent, Belgium.|Department of Prosthodontics, Malmö University, Malmö, Sweden.
authors.forename: Hugo
authors.initials: H
authors.lastname: De Bruyn
mesh_terms: D015921:Dental Implants; D003761:Dental Impression Technique; D006801:Humans; D066298:In Vitro Techniques; D008953:Models, Anatomic; D010969:Plastics
chemical_list: D015921:Dental Implants; D010969:Plastics
keywords: dental implant; digital impression; edentulous; intra-oral scan