title: Comparison of fracture strength and failure mode of different ceramic implant abutments.
abstract: BACKGROUND
  The whitish color of zirconia (ZrO2) abutments offers favorable esthetics compared with the grayish color of titanium (Ti) abutments. Nonetheless, ZrO2has greater opacity, making it difficult to achieve natural tooth color. Therefore, lithium disilicate (LaT) abutments have been suggested to replace metal abutments.
  
  
  OBJECTIVE
  The purpose of this in vitro study was to evaluate the fracture strength and failure mode of single-tooth implant restorations using ZrO2and LaT abutments, and to compare them with titanium (Ti) abutments.
  
  
  METHODS
  Five different types of abutments, Ti; ZrO2with no metal base; ZrO2with a metal base (ZrT); LaT; and LaT combination abutment and crown (LcT) were assembled on 40 Ti implants and restored with LaT crowns. Specimens were subjected to quasistatic loading using a universal testing machine, until the implant-abutment connection failed. As bending of the metal would be considered a clinical failure, the values of force (N) at which the plastic deformation of the metal occurred were calculated, and the rate of deformation was analyzed. Statistical analysis was done using the Mann-Whitney U test (α=.05).
  
  
  RESULTS
  Group ZrO2revealed the lowest resistance to failure with a mean of 202 ±33 N. Groups ZrT, LaT, and LaC withstood higher forces without fracture or debonding of the ceramic suprastructure, and failure was due to deformation of metal bases, with no statistically significant differences between these groups regarding the bending behavior.
  
  
  CONCLUSIONS
  Within the limitations of this in vitro study, it was concluded that LaT abutments have the potential to withstand the physiological occlusal forces that occur in the anterior region and that ZrO2abutments combined with Ti inserts have much higher fracture strength than pure ZrO2abutments.
authors: Assistant Professor, Department of Prosthodontics, Propaedeutics and Dental Materials, School of Dentistry, Christian-Albrechts University at Kiel, Kiel, Germany. Electronic address: aelsayed@proth.uni-kiel.de.
authors: Adham
authors: A
authors: Elsayed
authors: Research Associate, Department of Prosthodontics, Propaedeutics and Dental Materials, School of Dentistry, Christian-Albrechts University at Kiel, Kiel, Germany.
authors: Sebastian
authors: S
authors: Wille
authors: Research Associate, Department of Prosthodontics, Propaedeutics and Dental Materials, School of Dentistry, Christian-Albrechts University at Kiel, Kiel, Germany.
authors: Majed
authors: M
authors: Al-Akhali
authors: Professor and Chair, Department of Prosthodontics, Propaedeutics and Dental Materials, School of Dentistry, Christian-Albrechts University at Kiel, Kiel, Germany.
authors: Matthias
authors: M
authors: Kern
mesh_terms: D000044:Dental Abutments / Q000009:adverse effects*; D059605:Dental Implant-Abutment Design / Q000009:adverse effects*; D003776:Dental Porcelain / Q000009:adverse effects / Q000627:therapeutic use; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D006801:Humans; D014025:Titanium; D015040:Zirconium
chemical_list: C493120:lithia disilicate; D003776:Dental Porcelain; D015040:Zirconium; D014025:Titanium; C028541:zirconium oxide