The introduction of zirconia Y-TZP in dentistry has opened new frontiers regarding aesthetic and biocompatibility of dental materials. The aim of this study is to verify the maximum applicable load to the zirconia Y-TZP bridges in order to obtain the right dimension of the connectors. This material shows a high initial flexural strength (more than 1000 MPa) but it's necessary to determine if this value changes under strain, in other words under fatigue. To realize the trial, 40 zirconia bars (40 × 5 × 5 mm) were divided into 5 groups and tested under a pneumatic press that replaced cyclic strains. The first group (A) was stressed with high load to generate static fractures, the others (B, C, D, E) with lower strains as to identify a threshold, a pressure value that won't break the bars even after 2 millions compressions. With these results it was possible to obtain the Wöhler's curve for zirconia Y-TZP, a statistical curve that is to this day the base for the long range planning of the stressed mechanical elements. Our Wöhler's curve shows that the material has a fatigue limit of 400 MPa, a lower value compared with the static one tolerated (1000 MPa). This trial is an early scientific indication for a correct creation of connectors so that the material would resist in a complex system as the oral cavity
The Y-TZP zirconia in dentistry: A fatigue strength test [L'ossido di zirconio a struttura tetragonale: Test di resistenza alla fatica]
GHERLONE , FELICE ENRICO
2008-01-01
Abstract
The introduction of zirconia Y-TZP in dentistry has opened new frontiers regarding aesthetic and biocompatibility of dental materials. The aim of this study is to verify the maximum applicable load to the zirconia Y-TZP bridges in order to obtain the right dimension of the connectors. This material shows a high initial flexural strength (more than 1000 MPa) but it's necessary to determine if this value changes under strain, in other words under fatigue. To realize the trial, 40 zirconia bars (40 × 5 × 5 mm) were divided into 5 groups and tested under a pneumatic press that replaced cyclic strains. The first group (A) was stressed with high load to generate static fractures, the others (B, C, D, E) with lower strains as to identify a threshold, a pressure value that won't break the bars even after 2 millions compressions. With these results it was possible to obtain the Wöhler's curve for zirconia Y-TZP, a statistical curve that is to this day the base for the long range planning of the stressed mechanical elements. Our Wöhler's curve shows that the material has a fatigue limit of 400 MPa, a lower value compared with the static one tolerated (1000 MPa). This trial is an early scientific indication for a correct creation of connectors so that the material would resist in a complex system as the oral cavityI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
