Reliability of one-piece ceramic implant.
The fundamental aspects of damage initiation and accumulation in one-piece zirconium oxide endosseous dental implants remain to be investigated. This study tested the null hypothesis that there is no influence on mouth-motion fatigue reliability and failure modes between as-received and after full crown preparation on one-piece ceramic implants. Forty-eight one-piece Y-TZP ceramic implants (Nobel Biocare, Goteborg, Sweden) were utilized. All specimens were embedded in acrylic resin exposing the first two threads at 30 degrees angulation with respect to the vertical axis (as per ISO specification 14801). Full crown preparations were performed following prosthodontic guidelines for half of the specimens. As-received and prepared specimens were distributed among three step-stress profiles based on the specimens ultimate fracture strength. Specimens were step-stress fatigued until failure or survival. A master Weibull curve was generated from the data and the reliability for completion of a mission of 50,000 cycles at 600 N load calculated. No differences between the groups' reliability was observed. Failure mode for both groups was similar, where cracks initiated mainly at the tensile bending side of the second thread's internal diameter. The low Weibull modulus (<1) indicates that fatigue (<150,000 cycles) did not influence failure. Failure depended upon the applied load. Crown preparation did not influence the reliability of the one-piece ceramic implant. The null hypothesis was accepted. Fatigue did not influence the life time of ceramic implants at loads under 600 N.