Method: Thirty 3-unit IRFDPs were placed in thirty patients (18 females, 12 males, mean age 41.9 years). IRFDPs replaced 7 second premolars (4 in the maxilla, 3 in the mandible) and 23 first molars (15 in the maxilla, 8 in the mandible). Abutment preparations were performed for ceramic inlays and modified with a short retainer-wing bevel preparation within the enamel at the buccal and oral sides, with the aim to improve stress distribution, as well as to increase the adhesive bonding surface. The frameworks were scanned and milled out of zirconia ceramic (Vita In-Ceram YZ, Vita Zahnfabrik, Bad Säckingen, Germany), using the CEREC InLab CAD/CAM-system (Sirona) and the pontics were veneered with feldspathic ceramic. After air-abrasion of the ceramic bonding surfaces IRFDPs were luted adhesively with composite resin (Panavia 21, Kuraray). Clinical follow-up examinations were performed annually. Statistical analysis was performed using descriptive statistics and Kaplan–Meier survival analysis.
Result: The mean observation time was 50.2 months (±17.7 months). The cumulative survival rate using the Kaplan-Meier method was 94% after an observation period of 5 years. One patient dropped out of the study. Debonding was reported for three IRFDPs (10%), one of them failed finally after 49.4 months due to repeated debonding. Chipping of the veneering ceramic was reported in three cases (10%) which were repaired intraorally. Secondary caries were reported in 2 patients (6.7%). Nevertheless, the latter complications did not affect the clinical function of the involved IRFDPs.
Conclusion: The clinical outcome of zirconia ceramic IRFDPs constructed in the modified design after 5 years is promising, so that this novel design could recommended as a treatment modality to replace a missing tooth in the posterior region.