title: Comparative Evaluation of Fracture Resistance and Mode of Failure of Zirconia and Titanium Abutments with Different Diameters.
abstract: The purpose of the current study was to compare the fracture resistance and mode of failure of zirconia and titanium abutments with different diameters.
  
  
  
  Fourteen groups of abutments including prefabricated zirconia, copy-milled zirconia and titanium abutments of an implant system (XiVE, Dentsply) were prepared in different diameters. An increasing vertical load was applied to each specimen until failure occurred. Fracture resistance was measured in each group using the universal testing machine. Moreover, the failure modes were studied and categorized as abutment screw fracture, connection area fracture, abutment body fracture, abutment body distortion, screw distortion and connection area distortion. Groups were statistically compared using univariate and post-hoc tests. The level of statistical significance was set at 5%.
  
  
  
  Fabrication method (p = 0.03) and diameter (p < 0.001) had significant effect on the fracture resistance of abutments. Fracture resistance of abutments with 5.5 mm diameter was higher than other diameters (p < 0.001). The observed modes of failure were dependent on the abutment material as well. All of the prefabricated titanium abutments fractured within the abutment screw. Abutment screw distortion, connection area fracture, and abutment body fracture were the common failure type in other groups.
  
  
  
  Diameter had a significant effect on fracture resistance of implant abutments, as abutments with greater diameters were more resistant to static loads. Copy-milled abutments showed lower fracture resistance as compared to other experimental groups.
  
  
  
  Although zirconia abutments have received great popularity among clinicians and even patients selecting them for narrow implants should be with caution.
authors.affiliation: Department of Prosthodontics, Azad Dental School Tehran, Iran.
authors.forename: Reza
authors.initials: R
authors.lastname: Shabanpour
authors.affiliation: Department of Prosthodontics, Dental Research Center School of Dentistry, Tehran University of Medical Sciences Tehran, Iran.
authors.forename: Niloufar
authors.initials: N
authors.lastname: Mousavi
authors.affiliation: Department of Prosthodontics, Dental Research Center Dentistry Research Institute, Faculty of Dentistry, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Safoura
authors.initials: S
authors.lastname: Ghodsi
authors.affiliation: Associate Professor, Department of Prosthodontics, Dental Research Center Dentistry Research Institute, Faculty of Dentistry, Tehran University of Medical Sciences, Tehran, Iran, Phone: +989122014160 malikhasi@tums.ac.ir, m_alikhasi@yahoo.com.
authors.forename: Marzieh
authors.initials: M
authors.lastname: Alikhasi
mesh_terms: D000044:Dental Abutments; D059605:Dental Implant-Abutment Design / Q000379:methods*; D019232:Dental Restoration Failure; D006801:Humans; D008422:Materials Testing; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: D015040:Zirconium; D014025:Titanium
keywords: Copy milling; Diameter failure mode; Fracture resistance