title: Biomechanical evaluation of a microstructured zirconia implant by a removal torque comparison with a standard Ti-SLA implant.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the biomechanical bone tissue response to novel microstructured zirconia implants in comparison to sandblasted and acid-etched (SLA) titanium implants through the analysis of removal torque (RTQ) measurements.
  
  
  METHODS
  Ti-SLA implants with a sandblasted, large-grit and acid-etched surface were compared with zirconia implants with an acid-etched surface. All implants had the same shape, a diameter of 4.1 mm and a length of 10 mm. A total of 136 implants were placed in the maxillae of 17 miniature pigs. Six animals were sacrificed after both 4 and 8 weeks and five animals were sacrificed after 12 weeks, thus providing a total of 102 implants for RTQ testing (34 implants were reserved for future histological analysis). The RTQ analysis was successfully performed, using a mixed model regression with P-values calculated using the nonparametric Brunner-Langer method, on 100 of the 102 implants, two were excluded from the analysis.
  
  
  RESULTS
  The adjusted mean RTQ values for Ti-SLA implants were 131 Ncm (95% CI: 107-155) at 4 weeks, 128 Ncm (108-148) Ncm at 8 weeks, and 180 Ncm (153-207 Ncm) at 12 weeks of healing, whereas RTQ values for the zirconia implants were 110 Ncm (86-134), 97 Ncm (76-118) and 147 Ncm (121-174) at the corresponding time intervals. A comparison of the implant materials resulted in P-values of P = 0.114 at 4 weeks, P = 0.034 at 8 weeks and P = 0.105 at 12 weeks (significance set at P < 0.05).
  
  
  CONCLUSIONS
  Within the limits of the present study, it could be confirmed that the biomechanical bone-tissue response of the investigated zirconia implants is non-inferior to that of the well-documented, roughened titanium surface, at each time point, within the set tolerance. There were no statistically significant differences between the two materials after a healing period of 4 and 12 weeks. The RTQ values of both implant types increased significantly from the 8-week to the 12-week time point.
authors.affiliation: Department of Oral and Maxillofacial Surgery, Hannover Medical School, Hannover, Germany. bormann.kai-hendrik@mh-hannover.de
authors.forename: Kai-Hendrik
authors.initials: KH
authors.lastname: Bormann
authors.forename: Nils-Claudius
authors.initials: NC
authors.lastname: Gellrich
authors.forename: Heinz
authors.initials: H
authors.lastname: Kniha
authors.forename: Michel
authors.initials: M
authors.lastname: Dard
authors.forename: Marco
authors.initials: M
authors.lastname: Wieland
authors.forename: Michael
authors.initials: M
authors.lastname: Gahlert
mesh_terms: D000134:Acid Etching, Dental; D000818:Animals; D001696:Biomechanical Phenomena; D015921:Dental Implants; D003764:Dental Materials; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis; D005260:Female; D008855:Microscopy, Electron, Scanning; D012044:Regression Analysis; D013499:Surface Properties; D013552:Swine; D013556:Swine, Miniature; D014025:Titanium; D019415:Torque; D015040:Zirconium
chemical_list: D015921:Dental Implants; D003764:Dental Materials; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide