Brotthhållfastheten på monolitiska broar av flerskiktad zirkonia med olika konnektordimensioner och placering i en disk - En pilotstudie

Sammanfattning: Purpose: The purpose of this study was to evaluate the fracture strength of monolithic FDPs of multi-layered zirconia (YML) with different connector dimensions and placement in the disc. Material and method: Forty 3-unit monolithic anterior FDPs were produced, 212223, and divided in four groups (n=10) based on the different connector dimensions and strategies for placement in KATANATM Zirconia Yttria Multi-Layered (YML)-disc. The groups were as follows: EB12, produced with 12 mm  connector dimension and EB7, with 7 mm  connector dimension which were both placed in Enamel layer and Body layer 1 (flexural strength: 750 and 1000 MPa, respectively) in the disc, BB12, with 12 mm  connector dimension and BB7, produced with 7 mm  connector dimension both placed in Body layer 2 and 3 (both with 1100 MPa) in the disc. The specimens were artificially aged by 10 000 cycles in thermocycling. Then, one random specimen was selected from each group (4 in total) and cemented onto the model, subsequently loaded to fracture using a universal testing machine. The result was compiled and reported descriptively. Result: The FDP in group BB12 remained intact and fracturing only occurred in this model at 893 N. The FDP in group BB7 demonstrated the highest fracture strength (972 N), followed by EB12 (842 N) and EB7 which showed the lowest fracture strength (465 N). All these three FDPs broke mesially on the pontics. Conclusion: Within the limitations of this pilot study, the following conclusions can be drawn: the fracture strength of monolithic FDPs of multi-layered zirconia is affected by the connector dimension. Placement of FDPs with a small connector area should be avoided in the layers with lower strength. The choice of model material affects the result.