title: Load fatigue performance of conical implant-abutment connections.
abstract: OBJECTIVE
  Conical implant-abutment connections for platform switching have been recently introduced in implant systems. This study investigated the load fatigue performance of three conical abutment systems and their corresponding titanium and zirconia abutments.
  
  
  METHODS
  Regular-diameter implants of the Ankylos (AK), PrimaConnex (PC), and Straumann (ST) systems were tested with their corresponding titanium (Ti) and zirconia (Zr) abutments tightened to the recommended torque (n = 5 implant-abutment assemblies per group). A rotational load fatigue machine applied a sinusoidally varying tensile-compressive 21 N load to specimens at a 45-degree angle, producing an effective bending moment of 35 Ncm at a frequency of 10 Hz. The number of cycles to failure was recorded, with the upper limit set at 5 million cycles. Results were evaluated through analyses of variance.
  
  
  RESULTS
  Except for the ST Zr group, which showed no failures in four samples and one failure just below the screw head, and the AK Ti group, in which one sample was preserved without fracture, all groups experienced failure of at least one of the components, whether the abutment screw only, the abutment, and/or the implant neck. There were significant differences between systems. There was no difference between systems for the Ti abutments, and the ST group was significantly different from the AK and PC groups for the Zr abutments.
  
  
  CONCLUSIONS
  Ti conical abutments appear to have poorer load fatigue performance compared with earlier studies of external-hexagon connections. The load fatigue performance of Zr conical abutments varied and seemed to be highly system dependent. Many of the fractures in both the Ti and Zr abutment groups occurred within the implant, and retrieval would pose a significant clinical challenge. The clinician should weigh the mechanical, biologic, and esthetic considerations before selection of any implant system, connection type, or abutment material.
authors.affiliation: Department of Restorative Dentistry, National Dental Centre, Republic of Singapore.
authors.forename: Y L
authors.initials: YL
authors.lastname: Seetoh
authors.forename: Keson B
authors.initials: KB
authors.lastname: Tan
authors.forename: E K
authors.initials: EK
authors.lastname: Chua
authors.forename: H C
authors.initials: HC
authors.lastname: Quek
authors.forename: Jack I
authors.initials: JI
authors.lastname: Nicholls
mesh_terms: D000704:Analysis of Variance; D019245:Compressive Strength; D000044:Dental Abutments / Q000009:adverse effects; D059605:Dental Implant-Abutment Design / Q000009:adverse effects; D015921:Dental Implants; D017267:Dental Prosthesis Design / Q000009:adverse effects; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D019544:Equipment Failure Analysis; D013718:Tensile Strength; D014025:Titanium; D015040:Zirconium
chemical_list: D015921:Dental Implants; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide