title: Evaluation of artifacts generated by zirconium implants in cone-beam computed tomography images.
abstract: OBJECTIVE
  To evaluate zirconium implant artifact production in cone beam computed tomography images obtained with different protocols.
  
  
  METHODS
  One zirconium implant was inserted in an edentulous mandible. Twenty scans were acquired with a ProMax 3D unit (Planmeca Oy, Helsinki, Finland), with acquisition settings ranging from 70 to 90 peak kilovoltage (kVp) and voxel sizes of 0.32 and 0.16 mm. A metal artifact reduction (MAR) tool was activated in half of the scans. An axial slice through the middle region of the implant was selected for each dataset. Gray values (mean ± standard deviation) were measured in two regions of interest, one close to and the other distant from the implant (control area). The contrast-to-noise ratio was also calculated.
  
  
  RESULTS
  Standard deviation decreased with greater kVp and when the MAR tool was used. The contrast-to-noise ratio was significantly higher when the MAR tool was turned off, except for low resolution with kVp values above 80. Selection of the MAR tool and greater kVp resulted in an overall reduction of artifacts in images acquired with low resolution.
  
  
  CONCLUSIONS
  Although zirconium implants do produce image artifacts in cone-bean computed tomography scans, the setting that best controlled artifact generation by zirconium implants was 90 kVp at low resolution and with the MAR tool turned on.
authors.affiliation: Department of Oral Diagnosis, Division of Oral Radiology, Piracicaba Dental School, University of Campinas, São Paulo, Brazil. Electronic address: tataventorini@hotmail.com.
authors.forename: Taruska Ventorini
authors.initials: TV
authors.lastname: Vasconcelos
authors.affiliation: Department of Comprehensive Dentistry, Division of Oral and Maxillofacial Radiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
authors.forename: Boulos B
authors.initials: BB
authors.lastname: Bechara
authors.affiliation: Department of Pathology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
authors.forename: Clyde Alex
authors.initials: CA
authors.lastname: McMahan
authors.affiliation: Department of Oral Diagnosis, Division of Oral Radiology, Piracicaba Dental School, University of Campinas, São Paulo, Brazil.
authors.forename: Deborah Queiroz
authors.initials: DQ
authors.lastname: Freitas
authors.affiliation: Department of Comprehensive Dentistry, Division of Oral and Maxillofacial Radiology, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA.
authors.forename: Marcel
authors.initials: M
authors.lastname: Noujeim
mesh_terms: D016477:Artifacts; D054893:Cone-Beam Computed Tomography / Q000379:methods*; D015921:Dental Implants; D019047:Phantoms, Imaging; D015040:Zirconium
chemical_list: D015921:Dental Implants; D015040:Zirconium