Marginal Adaptation and Internal Fit of Posterior 3-Unit Zirconia FPDs Fabricated with Different CAD/CAM Systems.

The purpose of this study was to compare the accuracy of zirconia FPDs fabricated by different laboratory CAD/CAM system. Thirty-six FPD zirconia frameworks were fabricated on corresponding epoxy resin models that were duplicated from a master model of mandibular second premolar and second molar mounted in an acrylic block to simulate missing first mandibular tooth. Frameworks were divided into groups (n = 12) of three laboratory CAD/CAM systems: Cercon, Amann Girrbach, and Zirkonzahn. For the two factors, system and abutment type, the absolute marginal discrepancy (AMD) was measured before cementation. Internal fit was also determined at three sites after cementation. The data were analyzed statistically (α = 0.05). The effects of system and tooth type were not significant for AMD (p ⟩ 0.05). Both factors showed influence on the internal fit of FPDs (p ⟨ 0.05). Molars showed larger gaps in axial and occlusal sites (p = 0.001 and p = 0.003), and Cercon led in better occlusal adaptation compared with Amann Girrbach (p = 0.013). The systems tested did not show differences in AMD, despite different incorporated components. However, internal fit was significantly different between tooth type and system.