title: Osseointegration of zirconia implants with different surface characteristics: an evaluation in rabbits.
abstract: OBJECTIVE
  Zirconia ceramics are a viable alternative to titanium for use as dental implants. However, the smooth surface of zirconia means that longer healing periods are needed to accomplish osseointegration compared to roughened titanium surfaces. Surface modifications can be used to increase the roughness of zirconia. The aim of this study was to assess histologically and compare the degree of early bone apposition around zirconia dental implants with sandblasted, sintered, or laser-modified surfaces to that seen around surface-modified titanium implants. Removal torque was also measured and compared.
  
  
  METHODS
  Ninety-six implants--24 each of four types (sintered zirconia, laser-modified zirconia, sandblasted zirconia, and acid-etched titanium)--were placed in 48 New Zealand White female rabbits. One implant was inserted in each distal femur. Half of the specimens were harvested at 6 or 12 weeks and processed for light microscopic analysis; the area of bone-to-implant contact was measured morphometrically. The other half were evaluated for removal torque at 6 and 12 weeks.
  
  
  RESULTS
  No statistically significant differences existed in bone apposition between the different surfaces at either time point. Differences in removal torque were significantly different between titanium and sandblasted zirconia and between sintered zirconia and sandblasted zirconia, with the first mentioned demonstrating a higher torque value at 6 weeks. At 12 weeks, the only significant difference in removal torque was between titanium and sandblasted zirconia, with titanium demonstrating the higher value.
  
  
  CONCLUSIONS
  Comparable rates of bone apposition in the zirconia and titanium implant surfaces at 6 and 12 weeks of healing were observed. Removal torque values were similar for all implants with a roughened surface.
authors.affiliation: Department of Periodontics, School of Dentistry, Loma Linda University, Loma Linda, CA, USA. ohoffmann@llu.edu
authors.forename: Oliver
authors.initials: O
authors.lastname: Hoffmann
authors.forename: Nikola
authors.initials: N
authors.lastname: Angelov
authors.forename: Gregory-George
authors.initials: GG
authors.lastname: Zafiropoulos
authors.forename: Sebastiano
authors.initials: S
authors.lastname: Andreana
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D000818:Animals; D045662:Dental Etching / Q000379:methods; D015921:Dental Implants; D003764:Dental Materials / Q000737:chemistry*; D017267:Dental Prosthesis Design; D005260:Female; D005269:Femur / Q000473:pathology / Q000601:surgery; D006358:Hot Temperature; D007834:Lasers; D016348:Osseointegration / Q000502:physiology*; D010012:Osteogenesis / Q000502:physiology; D010027:Osteotomy / Q000379:methods; D011817:Rabbits; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry; D019415:Torque; D015040:Zirconium / Q000737:chemistry*
chemical_list: D015921:Dental Implants; D003764:Dental Materials; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide