Objectives: to record failure statistics of zirconia supported porcelain restorations and contributing factors in a combined retrospective clinical review from 4 prosthodontic practices.
Methods: The combined clinical experience with zirconia based restorations of 4 US prosthodontists (the authors) was tabulated using the following parameters: Patient gender, position of restored teeth, single crowns or FPDs, type of abutment (natural or core), natural or restored opposing teeth. Over a preceding period of up to 5 years, a total of 702 zirconia based units were placed in 207 patients (143 females, 64 males). 92% of units were made with the Katana (Noritake) zirconia with either CZR (Noritake) or Heraceram (Heraeus) Porcelain, 6% with the Lava (3M-ESPE) system, and 2% with other. FPDs accounted for 14% of all units.
Results: The combined total failure rate over the study period was 2.8% (20 units - 15 Katana, 3 Everest/Creation, 2 Lava, 2 Procera/Rondo) with following breakdown: 14 porcelain chips (2%); 4 porcelain fractures (0.5%); 2 core fractures (0.2%). Only 60% of the observed failures (12 restorations) necessitated replacement. 35% of failures occurred in posterior teeth and 65% in anterior teeth. Over 70% of the failures occurred after 3-5 years of service. Due to the relatively low failure percentage no correlation could be established with other variables except for recorded bruxism or accidental impact.
Conclusions: The porcelain/zirconia restorative systems monitored in this retrospective study exhibited a combined failure rate of 2.8%. Of all failures only 60% necessitated replacements. The recorded failure rate was significantly lower than previously reported and within range of published PFM performance statistics.