title: Effect of digitizing techniques on the fit of implant-retained crowns with different antirotational abutment features.
abstract: BACKGROUND
  The development of computer-aided design/computer-aided manufacturing technology has enabled the fabrication of implant-retained restorations. However, information on the marginal and axial accuracy of restorations fabricated by different digitizing techniques with different antirotational abutment features is not sufficient.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to evaluate the influence of digitizing techniques on the fit of implant-retained crowns with 2 antirotational features.
  
  
  METHODS
  An experimental working cast housing a tissue-level dental implant was created. Resin-retained abutments with different antirotational features were connected to the implant. Optical impressions of 2 abutment types were obtained separately with 1 chairside and 2 laboratory approaches. Alumina silicate restorations were milled from chairside optical impressions, and ceramic oxide cores were milled from laboratory optical impressions. Restoration fit was evaluated from axial sections of restorations with silicone materials representing the marginal and axial gaps. Axial and marginal fits were measured on digital photographs of the sectioned specimens with a computer program. Two-way ANOVA was used to compare differences between abutments with 2 different antirotational features and digitizing techniques separately for the marginal and axial fits of single implant-retained crowns. A post hoc least significant difference test was used to compare digitizing techniques (α=.05).
  
  
  RESULTS
  Significant differences in the marginal fit of single-implant-retained crowns were found among digitizing techniques (P=.011) and between antirotational features (P<.001). No significant difference in the axial fit of single-implant-retained crowns was found among digitizing techniques (P=.905) or between antirotational features (P=.075).
  
  
  CONCLUSIONS
  Within the limitations of this in vitro study, the marginal fit of single-implant-retained crowns was affected by antirotational abutment features. Furthermore, digitizing techniques were found to play an important role in the marginal fit of single-implant-retained restorations.
authors.affiliation: Research Associate, Faculty of Dentistry, Department of Prosthodontics, Hacettepe University, Ankara, Turkey. Electronic address: g_emul@yahoo.com.
authors.forename: Guliz
authors.initials: G
authors.lastname: Aktas
authors.affiliation: Assistant Professor, Faculty of Dentistry, Department of Prosthodontics, Kirikkale University, Kirikkale, Turkey.
authors.forename: Nihal
authors.initials: N
authors.lastname: Özcan
authors.affiliation: Research Assistant, Faculty of Dentistry, Department of Prosthodontics, Hacettepe University, Ankara, Turkey.
authors.forename: Didem Hasanoglu
authors.initials: DH
authors.lastname: Aydin
authors.affiliation: Retired Professor, Faculty of Dentistry, Department of Prosthodontics, Hacettepe University, Ankara, Turkey.
authors.forename: Erdal
authors.initials: E
authors.lastname: Şahin
authors.affiliation: Professor, Faculty of Dentistry, Department of Prosthodontics, Hacettepe University, Ankara, Turkey.
authors.forename: Kıvanç
authors.initials: K
authors.lastname: Akça
mesh_terms: D000538:Aluminum Silicates / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry; D017076:Computer-Aided Design; D003442:Crowns; D000044:Dental Abutments; D059605:Dental Implant-Abutment Design; D019250:Dental Implants, Single-Tooth; D003761:Dental Impression Technique; D018772:Dental Marginal Adaptation; D019094:Dental Prosthesis, Implant-Supported; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008422:Materials Testing; D010781:Photography / Q000379:methods; D012399:Rotation; D012828:Silicones / Q000737:chemistry; D013499:Surface Properties; D013813:Therapy, Computer-Assisted
chemical_list: D000538:Aluminum Silicates; D012828:Silicones