Fracture strength of zirconia implants after artificial aging.

BACKGROUND

Zirconia (ZrO(2)) might be an alternative material to titanium (Ti) for dental implant fabrication. However, no data are available on the fracture strength of one-piece ZrO(2) oral implants.

PURPOSE

The objective of this study was to evaluate the fracture strength of ZrO(2) implants after exposure to the artificial mouth.

MATERIALS AND METHODS

One hundred twenty ZrO(2) and Ti implants were used. The Ti implants were divided into two control groups (A and B). ZrO(2) implants manufactured from yttria-stabilized tetragonal ZrO(2) polycrystal (Y-TZP) in group C, from Y-TZP dotted with alumina (Y-TZP-A) in group D, and from Y-TZP-A with a modified surface in groups E and F were used. In group F, the implant heads were prepared, and in group G, the implants were restored with ZrO(2) crowns. Each group included 16 samples with the exception of group D, which included 24 samples. A subgroup of each implant type (eight implants) was subjected to thermomechanical cycling in a chewing simulator prior to fracture testing. Test specimens were then loaded until a fracture occurred.

RESULTS

Seven of the 120 samples failed in the chewing simulator. ZrO(2) implant fracture occurred at 725 to 850 N when the implants were not prepared, and at 539 to 607 N when prepared. The samples in group A fractured at the level of the abutment screw. All ZrO(2) implants fractured at the level of the Technovit resin (Heraeus Kulzer GmbH & Co., Wehrheim, Germany). No fracture of the ZrO(2) crowns in group G was observed.

CONCLUSION

Mean fracture strength values obtained were all within the limits of clinical acceptance. However, implant preparation had a statistically significant negative influence on the implant fracture strength. Long-term clinical data are necessary before one-piece ZrO(2) implants can be recommended for daily practice.