title: Marginal bone-level alterations of loaded zirconia and titanium dental implants: an experimental study in the dog mandible.
abstract: OBJECTIVE
  The aim was to test whether or not the marginal bone-level alterations of loaded zirconia implants are similar to the bone-level alterations of a grade 4 titanium one-piece dental implant.
  
  
  METHODS
  In six dogs, all premolars and the first molars were extracted in the mandible. Four months later, three zirconia implants (BPI, VC, ZD) and a control titanium one-piece (STM) implant were randomly placed in each hemimandible and left for transmucosal healing (baseline). Six months later, CAD/CAM crowns were cemented. Sacrifice was scheduled at 6-month postloading. Digital X-rays were taken at implant placement, crowns insertion, and sacrifice. Marginal bone-level alterations were calculated, and intra- and intergroup comparisons performed adjusted by confounding factors.
  
  
  RESULTS
  Implants were successfully placed. Until crown insertion, two implants were fractured (one VC, one ZD). At sacrifice, 5 more implants were (partly) fractured (one BPI, four ZD), and one lost osseointegration (VC). No decementation of crowns occurred. All implant systems demonstrated a statistically significant (except VC) loss of marginal bone between baseline and crown insertion ranging from 0.29 mm (VC; P = 0.116) to 0.80 mm (ZD; P = 0.013). The estimated marginal bone loss between baseline and 6 months of loading ranged between 0.19 mm (BPI) and 1.11 mm (VC), being statistically significant for STM and VC only (P < 0.05). The changes in marginal bone levels were statistically significantly different between zirconia implants and control implants (STM vs. BPI P = 0.007; vs. VC P = 0.001; vs. ZD P = 0.011).
  
  
  CONCLUSIONS
  Zirconia implants were more prone to fracture prior to and after loading with implant-supported crowns compared to titanium implants. Individual differences and variability in the extent of the bone-level changes during the 12-month study period were found between the different implant types and materials.
authors: Clinic for Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich, Zurich, Switzerland.
authors: Daniel S
authors: DS
authors: Thoma
authors: Clinic for Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich, Zurich, Switzerland.
authors: Goran I
authors: GI
authors: Benic
authors: Department of Veterinary Clinical Sciences, University of Santiago de Compostela, Lugo, Spain.
authors: Fernando
authors: F
authors: Muñoz
authors: Department of Prosthodontics, Albert-Ludwigs-University, Freiburg, Germany.
authors: Ralf
authors: R
authors: Kohal
authors: Universidad Complutense, Madrid, Spain.
authors: Ignacio
authors: I
authors: Sanz Martin
authors: Department of Veterinary Clinical Sciences, University of Santiago de Compostela, Lugo, Spain.
authors: Antonio G
authors: AG
authors: Cantalapiedra
authors: Clinic for Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich, Zurich, Switzerland.
authors: Christoph H F
authors: CH
authors: Hämmerle
authors: Clinic for Fixed and Removable Prosthodontics and Dental Material Science, University of Zurich, Zurich, Switzerland.
authors: Ronald E
authors: RE
authors: Jung
mesh_terms: D016301:Alveolar Bone Loss; D000818:Animals; D003442:Crowns; D003758:Dental Implantation, Endosseous; D015921:Dental Implants; D017267:Dental Prosthesis Design; D019094:Dental Prosthesis, Implant-Supported; D004285:Dogs; D008334:Mandible; D014025:Titanium; D015040:Zirconium
chemical_list: D015921:Dental Implants; D015040:Zirconium; D014025:Titanium
keywords: X-rays; bone; crowns; dental implants; titanium; zirconium oxide