A Retrospective Study on the 15-yearTreatment Outcome of implant

Objectives: This study was aimed to evaluate cumulative survival rate (CSR) of Osseointegrated implants (Nobel Biocare, Sweden) for 15 and to determine risk factors of implant failure. Methods: A total of 541 machined and TiUnite implants were placed consecutively in 156 patients at the Korea University Guro Hospital. Two hundred sixty-four machined implants were placed in 79 patients since 1993 and 277 TiUnite implants were placed in 77 patients since 2001. Kaplan-Meier estimate of implant survival was undertaken to examine CSR. Cox proportional hazards regression was used to assess the influence of potential risk factors on implant survival after adjusting for confounding attributable to age and gender. The level of statistical significance was set as a=0.05. Results: Thirty-eight implants (35 in machined implants; 3 in TiUnite implants) out of 546 implants failed (15-year CSR: 86.22%). The 15-year and 5-year CSR of machined implant were 80.7% and 85.9% respectively. The 5-year CSR of TiUnite implants was 98.2%. Machined implants were almost 5.7 times more likely to experience implant failure than TiUnite implants (95%CI: 3.4, 11.7) for the 5-year CSR. Patients having systemic disease were 30% more likely to experience implant failure than patients without systemic disease (95%CI: 0.50, 0.97). Patients with other surgical procedures such as bone graft and maxillary sinus graft were 40% more likely to experience implant failure than patients without similar surgical procedures (95%CI: 0.43, 0.87). There was statistically significant difference of implant failure among anatomic location of implants (p-value=0.0226) and the kind of edentulous sites by Kennedy classification (p-value=0.0109). Conclusion: TiUnite implants survived longer than machined implants for the 5 years. Presence of systemic disease and combination of other surgical procedures increased implant failure. Implant survival was dependent upon the anatomic location of implants and the kind of edentulous sites by Kennedy classification.