title: A Novel Method to Evaluate Precision of Optical Implant Impressions with Commercial Scan Bodies-An Experimental Approach.
abstract: OBJECTIVE
  Optical transfer is realized with system-specific transfer posts (scan bodies) mounted on dental implants or on implant analogs. This study presents a novel algorithm for creation of geometry on the surface of dental implant scan bodies and examines the precision of the optical acquisition of scan bodies and the precision of the position of the screw-tightened scan bodies on dental implant analogs.
  
  
  METHODS
  Scan bodies of two different implant manufacturers (S1, S2), one with a horizontal and two with different conical implant-abutment geometries were screw tightened to implant analogs in stone casts with a 10 Ncm torque. The stone casts were scanned ten times with a dental lab scanner. Each scan body was removed and positioned ten times; after each repositioning, a scan was performed. The cylinder axis of every scan body and the occlusal horizontal scan body surface was virtually reconstructed. At the intersection of the cylinder axis and the horizontal plane a point was marked. The mean deviation of this point in consecutive scans and the angle between the scan body axes in the virtual models were measured, and the standard deviation was calculated. Statistical significance of the results was tested with a Kruskal-Wallis Test and Mann-Whitney U-test for pairwise comparison (p < 0.05).
  
  
  RESULTS
  The mean deviation of the angle between two scan bodies was 0.05° (SD 0.04°) (S1) and 0.14° (SD 0.08°) (S2). After detachment and repositioning of the scan bodies the mean deviation was 0.05° (SD 0.03°) (S1) and 0.16° (SD 0.08°) (S2). The mean deviation of the central point was 5.7 μm (SD 3.4 μm) without detachment and 4.9 μm (SD 2.6 μm) after detachment and repositioning (S1). For system S2 the mean deviation of the central point was 13.4 μm (SD 7.2 μm) after repeated scanning and 15 μm (SD 5 μm) after detachment, repositioning, and repeated scanning.
  
  
  CONCLUSIONS
  The precision of extraoral scanning of scan bodies is dependent on the scan body surface design and geometry. The precision of scanning with an extraoral model scanner differed between the scan body geometries and inter-scan body distances. The precision of dental implant scan body scanning was not significantly influenced by detachment and repositioning of the scan body.
authors.affiliation: Department of Oral and Maxillofacial Surgery, University Medical Center, Freiburg, Germany.
authors.forename: Tabea
authors.initials: T
authors.lastname: Fluegge
authors.affiliation: Department of Oral and Maxillofacial Surgery, University Medical Center, Freiburg, Germany.|Department of Restorative Dentistry Hamdan bin Mohammed College of Dental Medicine Mohammed bin Rashid University for Health and Medical Sciences, Dubai, UAE.
authors.forename: Wael
authors.initials: W
authors.lastname: Att
authors.affiliation: Department of Oral Prosthodontics, University Medical Center, Freiburg, Germany.
authors.forename: Marc
authors.initials: M
authors.lastname: Metzger
authors.affiliation: Department of Oral and Maxillofacial Surgery, University Medical Center, Freiburg, Germany.
authors.forename: Katja
authors.initials: K
authors.lastname: Nelson
mesh_terms: D000465:Algorithms; D017076:Computer-Aided Design; D015921:Dental Implants; D003761:Dental Impression Technique; D017267:Dental Prosthesis Design / Q000379:methods; D006801:Humans
chemical_list: D015921:Dental Implants
keywords: CAD/CAM; Dental implants; dental implant-supported prosthesis: dental implant/abutment connection; laser scanning