Fractured zirconia implants and related implant designs: scanning electron microscopy analysis

Two fractured one-piece experimental (commercially unavailable) zirconia implants were analyzed using scanning electron microscope (SEM) analysis to identify failure origins and aid in understanding the failure mechanisms. Modifications to the zirconia implant design are suggested to minimize such fracture incidences.

Two zirconia implants fractured during the final torquing in the maxillary ridge using the prescribed hand torque wrench. The implants were subsequently retrieved and prepared for optical and SEM evaluation. Critical attention was given to the fractography (crack morphology) of the fractured implants to identify the fracture origin.

Events related to initiation and propagation of the crack front could be detected from the morphology of the fractured surfaces. Unfavorable torque and bending forces applied on the implant during surgical placement and the inherent flaws in the material may have resulted in crack initiation and implant failure.

Caution must be exercised when placing zirconia implants in dense bone sites. Modification of surgical protocols for the intended implant site may be necessary. Improvement in design features specific to zirconia implants, and strict quality control during manufacture is essential to minimize the likelihood of fracture.