Press-on Veneering Technique on Zirconia Frameworks – Preliminary Results

Objective: Veneer fractures are the most reported events with respect to all-ceramic restorations based on zirconia frameworks. The purpose of this prospective clinical study was to evaluate the longevity of a press-on veneering technique on three different zirconia framework materials. Methods: In 45 patients 106 zirconia based single posterior crowns were inserted between March 2004 and August 2009. The mean age of the 20 male and 25 female patients was 42.2 years (min 20 yrs, max 63 yrs). 15 patients each were provided with all-ceramic restorations based on three different framework materials: 36 frameworks of HIP zirconia based crowns (DCS Zirkon, DCS, Alschwil Switzerland) were inserted. The pre-sintered zirconia framework materials Lava Ceram (3M Espe, Seefeld, Germany) and ZirCAD (Ivoclar Vivadent, Schaan, Liechtenstein) were fabricated 31 and 39 times, respectively. All copings were layered using the press-on technique IPS e.max ZirPress (Ivoclar-Vivadent). The mean observation time was 2 years and ranged up to 4.7 years. At the annual examinations one main focus was the performance of the veneering material. Results: Two major chippings of the veneering material occurred after 3years on a ZirCAD coping and after 0.6 years on a Lava framework. The events were so severe, that the restorations had to be renewed. The Kaplan Maier analysis over a time period of 4.6 years (CI: lower bound: 4.4 yrs; upper bound: 4.8 yrs) revealed a survival rate of 95% for all crowns. There was no statistical difference between the three different framework materials at p ≤0.05 (log rank test). Conclusions: Within the limits of the study the press-on technique showed promising results with respect to the fracture rate. However, these are preliminary results. The study was supported by Ivoclar-Vivadent