Fracture behavior of zirconia implant abutments is influenced by superstructure-geometry.
OBJECTIVE
The purpose of this in vitro study was to evaluate the influence of the superstructure-geometry on the fracture behavior of zirconia abutments (Compartis, DeguDent GmbH, Hanau, G).


METHODS
Four different groups (n = 8) representing anterior single crown replacement were prepared. In groups 1 and 2, the implants were restored with customized all-ceramic abutments and anatomically shaped crowns (chromium cobalt alloy). Groups 3 and 4 received crowns with a geometry according to the international standard ISO 14801 (dynamic fatigue test for endosseous dental implants) with a spherical contact area. Groups 2 and 4 were subjected to mechanical aging in a chewing simulator (50 N × 1,200,000 cycles). Static loading until fracture was performed using a universal testing device at an angle of 30° to the implant axis. Fracture patterns were analyzed using SEM.


RESULTS
In group 2, only one specimen survived mechanical aging. In group 4, one specimen fractured during the chewing simulation. Groups 1 and 2 showed significantly lower load-bearing capacity than groups 3 and 4. Artificial aging did not influence the fracture resistance. The SEM analysis revealed fatigue-related fracture patterns in those specimens, which failed during artificial aging.


CONCLUSIONS
Drawing conclusions from ISO testing concerning clinical performance appears to be critical as anatomic superstructure geometries induce different fracture behaviors.


CONCLUSIONS
ISO testing of zirconia abutments should be accompanied by load-bearing capacity testing under simulated clinical conditions to predict clinical performance.
Department of Prosthetic Dentistry and Dental Materials Sciences, Dental School and Clinics, Saarland University, Homburg, Saar, Germany, frank.nothdurft@uks.eu.
Frank P
FP
Nothdurft
Konrad
K
Neumann
Andreas W
AW
Knauber
D003442:Crowns; D000044:Dental Abutments; D015921:Dental Implants; D015040:Zirconium
D015921:Dental Implants; D015040:Zirconium