title: A new triple-scan protocol for 3D fit assessment of dental restorations.
abstract: OBJECTIVE
  Assessing the level of precision entailed by the virtual fit of dental restorations is a very challenging issue. A cement space between an abutment tooth and a dental restoration is a clinical requisite that precludes the application of conventional best-fit registration protocols routinely applied in industrial precision measurements. Since two-dimensional fit assessment techniques currently used in dentistry miss important information about the third dimension, a new protocol was developed to provide three-dimensional information for the virtual registration of the digitized restoration with respect to the abutment.
  
  
  METHODS
  CAD/CAM was used to produce 10 titanium single crown copings for five gypsum master casts each, representing a molar prepared for a full crown. An industrial noncontact scanner was used for digitizing the components. Registration of surface data sets was achieved by a new triple-scan protocol. For statistical analysis and repeatability testing of the triple-scan protocol, mean distances of the cement space of all copings on their respective abutments were measured three times.
  
  
  RESULTS
  The validity of the approach is verified by intraclass correlation coefficients that revealed an almost perfect coefficient for repeatability (ICC = 0.981, P < .001) with a 95% confidence range between 0.970 and 0.989.
  
  
  CONCLUSIONS
  The triple-scan protocol represents a reliable registration approach for surface data sets in dental applications and eliminates the limitations of conventional best-fit registration protocols when a cement space or gap is present between a restoration and its underlying abutment. Future fit assessment investigations can implement this approach of obtaining detailed information of component precision in all spatial orientation.
authors.affiliation: University Clinic Erlangen, Dental Clinic 2-Prosthodontics, Glückstr 11, 91054 Erlangen, Germany. stefan.holst@uk-erlangen.de
authors.forename: Stefan
authors.initials: S
authors.lastname: Holst
authors.forename: Matthias
authors.initials: M
authors.lastname: Karl
authors.forename: Manfred
authors.initials: M
authors.lastname: Wichmann
authors.forename: Ragai-Edward T
authors.initials: RE
authors.lastname: Matta
mesh_terms: D003442:Crowns; D000044:Dental Abutments; D003738:Dental Cements; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D003765:Models, Dental; D008963:Molar; D017755:Prosthesis Fitting; D015203:Reproducibility of Results; D018709:Statistics, Nonparametric; D014584:User-Computer Interface
chemical_list: D003738:Dental Cements