Outcome of HIP Zirconia Fixed Dental Prosthesis after 7 Years

Objectives: Due to rare long-term clinical data of zirconia supported fixed dental prosthesis the purpose of this prospective study was to evaluate the clinical outcome of anterior, posterior and combined anterior/posterior fixed dental prosthesis made of HIP zirconia framework material (DCS Dental AG, Allschwil, Switzerland). Methods: Between December 1998 and September 2007 105 FDPs were inserted in 70 patients. Sixteen anterior, 59 posterior and 30 combined FDPs replaced 1 to 5 missing teeth. Vita D was used as veneering material. All restorations were either adhesively luted (23.8%) or inserted with zinc oxide phosphate cement (76.2%). Follow-up appointments were performed 6 months after insertion, then annually. Necessity of renewing a restoration was defined as failure. Results: Thirteen patients (18.6%) with 22 FDPs were defined as drop-outs. For the remaining 83 FDPs the mean observation time was 62.4 months (range: 6.9-130.4 months). After 5 and 7 years the Kaplan-Meier-survival-rate was 85.8% and 77.7%, respectively. In total 13 (4 technical, 9 biological) failures in 12 patients were observed. Log rank test showed that the kind of cementation did not significantly influence the survival (p=0.7). The complication-free rate concerning chipping of the veneering material after 5 and 7 years was 89.2% and 80.3%, respectively. Conclusions: Although HIP zirconia was used, 3 framework fractures were reported. One fracture had progressed from an access for endodontical treatment of an abutment tooth two years after trepanation, 1 fracture was detected in the connector area of two pontics in a 5-unit FDP, the 3rd fracture occurred in the connector area to a pontic that had a length of 9.5 mm. Summing up, the estimated survival rate of the present study is still in the range of the survival rate for zirconia FDPs known from literature. Supported by DCS Dental AG, Allschwil, Switzerland