Clinical survival of posterior zirconia crowns in private practice

Objectives: This study evaluated and compared the clinical success of zirconia crowns and conventional porcelain-fused-to-metal (PFM) crowns on posterior teeth in private practice. Methods: A total of 2,635 premolar and molar crowns (1944 all-ceramic; 691 PFM) fabricated by one dental laboratory were followed over intervals ranging from 2 to 57 months by the respective private practitioners using a print survey. In the all-ceramic group, one veneering porcelain (CZR, Noritake) was used in combination with three coping systems (Lava, 3M ESPE; Procera, Nobelbiocare; Katana, Noritake). The private practitioners were asked to indicate any post-cementation complications (i.e. porcelain chipping), all of which were considered failures. Kaplan-Meier Survival Analysis was used for statistical analyses. Results: Mean survival time for posterior crowns was 52 months with a survival probability of 98.1% for all-ceramic 95.8% for PFM crowns, indicating no significant difference (r=0.107). Survival probabilities of individual zirconia coping systems were 97.3% for Lava, 99.5% for Procera, and 99.7% for Katana, which were not significantly different from each other (r=0.072). For the 1107 molar and 837 premolar crowns, mean survival probabilities were not significantly different (r=0.586) with 97.5% for molar 98.9% for premolar crowns. Conclusions: Survival times and survival probabilities of zirconia crowns made in private practice on posterior teeth did not differ from PFM crowns. Success rates were independent of location (molar or premolar).