title: Three-dimensional accuracy of a digitally coded healing abutment implant impression system.
abstract: OBJECTIVE
  This study examined the three-dimensional (3D) accuracy of the Encode Impression System (EN) in transferring the locations of two implants from master models to test models and compared this to the direct impression (DI) technique. The effect of interimplant angulation on the 3D accuracy of both impression techniques was also evaluated.
  
  
  METHODS
  Seven sectional polymethyl methacrylate mandibular arch master models were fabricated with implants in the first premolar and first molar positions. The implants were placed parallel to each other or angulated mesiodistally or buccolingually with total divergent angles of 10, 20, or 30 degrees. Each master model was secured onto an aluminum block containing a gauge block, which defined the local coordinate references. Encode healing abutments were attached to the implants before impressions were made for the EN test models; pickup impression copings were attached for the DI test models. For the seven test groups of each impression technique, a total of 70 test models were fabricated (n = 5). The EN test models were sent to Biomet 3i for implant analog placement. The centroid of each implant or implant analog and the angular orientation of the long axis relative to the x- and y-axes were measured with a coordinate measuring machine. Statistical analyses were performed.
  
  
  RESULTS
  Impression technique had a significant effect on y distortion, global linear distortion, and absolute xz and yz angular distortions. Interimplant angulation had significant effects on x and y distortions. However, neither impression technique nor interimplant angulation had a significant effect on z distortion.
  
  
  CONCLUSIONS
  Distortions were observed with both impression techniques. However, the results suggest that EN was less accurate than DI.
authors.forename: Simon D
authors.initials: SD
authors.lastname: Ng
authors.forename: Keson B
authors.initials: KB
authors.lastname: Tan
authors.forename: K H
authors.initials: KH
authors.lastname: Teoh
authors.forename: Ansgar C
authors.initials: AC
authors.lastname: Cheng
authors.forename: Jack I
authors.initials: JI
authors.lastname: Nicholls
mesh_terms: D017076:Computer-Aided Design; D000044:Dental Abutments / Q000592:standards*; D015921:Dental Implants; D003760:Dental Impression Materials; D003761:Dental Impression Technique / Q000592:standards*; D006801:Humans; D003765:Models, Dental
chemical_list: D015921:Dental Implants; D003760:Dental Impression Materials