Five-year clinical outcome of posterior zirconia ceramic inlay-retained FDPs with a modified design

To evaluate the 5-year clinical outcome of posterior inlay-retained fixed dental prostheses (IRFDPs) with a modified design made from zirconia ceramic (Vita In-Ceram YZ, Vita Zahnfabrik, Bad Säckingen, Germany).

Thirty 3-unit IRFDPs were placed in 30 patients. Seven IRFDPs replaced the second premolars (4 in the maxilla, 3 in the mandible), and 23 replaced the first molars (15 in the maxilla, 8 in the mandible). Preparations were performed in accordance with general principles for ceramic inlay restorations and modified with a short retainer-wing bevel preparation within the enamel at the buccal and oral sides. The frameworks were milled from zirconia ceramic, and the pontics were veneered with feldspathic ceramic. After air-abrasion of bonding surfaces, IRFDPs were bonded with an adhesive composite resin. The patients were recalled 6-12 months after placement, and then annually. Kaplan-Meier analysis was used to calculate the survival and complication rates of the IRFDPs.

After a mean observation time of 64.4 (SD=17.6) months (min 15, max 95.6), the 5-year cumulative survival of IRFDPs was 95.8%. Debonding was reported for two IRFDPs (6.9%), one of them failed finally after 49.4 months due to repeated debonding. Chipping of the veneering ceramic was reported in three cases (10.5%). Secondary caries were reported in 2 patients (8.1%). Nevertheless, the latter complications did not affect the clinical function of the involved IRFDPs.

The 5-year clinical outcome of zirconia-based IRFDPs fabricated in the modified design is encouraging, so that they may represent a treatment alternative to replace posterior single missing teeth, taking into consideration the appropriate case selection.