title: Fracture resistance of different implant abutments supporting  all-ceramic single crowns after aging.
abstract: OBJECTIVE
  To test the mechanical properties of three different restorative materials for implant abutments supporting all-ceramic single crowns.
  
  
  METHODS
  Thirty implants with butt-joint connections were distributed into three test groups: Group A with 10 one-piece zirconia abutments, Group U with 10 titanium abutments, and Group T with 10 titanium-zirconia hybrid abutments. Monolithic zirconia single crowns were cemented and artificially aged. The crowns were loaded at a 30-degree angle in a universal testing machine until fracture or bending. Additionally, after removal of the restorations, the implant-abutment interface of the fixtures was inspected using a scanning electron microscope (SEM).
  
  
  RESULTS
  In Group A, the abutments failed on average at 336.78 N, in Group U at 1000.12 N, and in Group T at 1296.55 N. The mean values between Groups T and U (P = 0.009), and between Group A and Groups T and U (P < 0.001) were significantly different. The abutments in Group A failed early due to fractures of the internal parts and parts close to the implant neck. In Groups T and U, failures occurred due to bending of the implant neck.
  
  
  CONCLUSIONS
  This experimental study proves that hybrid and titanium abutments have similar mechanical properties. One-piece abutments made of zirconia showed significantly lower fracture resistance.
authors.forename: Michael
authors.initials: M
authors.lastname: Stimmelmayr
authors.forename: Philipp
authors.initials: P
authors.lastname: Heiß
authors.forename: Kurt
authors.initials: K
authors.lastname: Erdelt
authors.forename: Josef
authors.initials: J
authors.lastname: Schweiger
authors.forename: Florian
authors.initials: F
authors.lastname: Beuer
mesh_terms: D002516:Ceramics / Q000737:chemistry*; D003442:Crowns; D000044:Dental Abutments; D059605:Dental Implant-Abutment Design; D019250:Dental Implants, Single-Tooth; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D006801:Humans; D008422:Materials Testing; D014025:Titanium / Q000737:chemistry*; D015040:Zirconium / Q000737:chemistry*
chemical_list: D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide