4-Unit Molar Fixed Partial Dentures Made from Highly Translucent and Multilayer Zirconia Materials: An In Vitro Investigation

Background: Modern zirconia blanks for the fabrication of dental CAD/CAM restorations provide a layer structure with color and strength transitions. Variation in yttria content has particular effect on characteristics materials. The properties may vary depending milling position within blank. Especially wide-span fixed partial dentures (FPDs), relevant effects clinical performance might result. This study investigated if application high-translucent positioning multilayer affect vitro 4-unit FPDs. Methods: FPDs were fabricated from monolayer 3Y-TZP-A, 3Y-TZP, 4Y-TZP, 5Y-TZP, 4Y/5Y-TZP, different positions (3Y-TZP/5Y-TZP). adhesively luted to resin abutment teeth, divided into groups (n = 8 each): “baseline” (24 h water-storage)/“TCML” (chewing simulation by means thermalcycling mechanical loading), loaded fracture. statistics included mean standard deviation, one-way ANOVA, Bonferroni post hoc test, Pearson correlation (α 0.05). Results: fracture force values varied between 803.8 ± 171.7 N (5Y) 1474.1 193.0 (3Y) (baseline) 713.5 190.9 1337.4 205.6 (TCML). Significantly (p 0.000) results individual significant differences ≤ 0.039) found. Conclusions: Positioning affected only slightly. Multilayer, 4Y-TZP seem appropriate molar Application 5Y-TZP is critical.