Methods: Three-unit fully sintered FPDs were prepared from Cercon (CR), Lava (LW), Zenotec Zr Bridge (WD), In-Ceram YZ (YZ) and IPS e-max ZirCAD (ZC) materials. Raman spectroscopy was used to identify and map the distribution of the m-ZrO2 phase at cervical crown margins, pontic and connector regions (n:3x2). The percentage volume of the m-ZrO2 phase (%Vm) was calculated per region. An optical profiler was used to measure amplitude 3D-surface roughness parameters at the same regions and a SEM for the microstructure.
Results: The m-ZrO2 phase was detected in all the specimens, with the highest intensity located at the crown margins. WD showed the lowest %Vm content (0-3.14%), followed by LW (10.26-12.39%), CR (11.72-13.19%), ZC (11.13-14.10%) and YZ (12.15-14.99%). No statistically significant difference was found among LW, CR, ZC, YZ per region. Within each material group, significant differences were found between margin-pontic/connector (WD, YZ), margin-connector (CR, ZC) and margin-pontic (LW). 3D roughness parameters ranged within 0.49-1.94 um (Sa) and 6.26-14.46 um (Sz). No statistically significant differences were found in Sa, Sz among regions for CR and YZ. WD demonstrated the highest values at the margins (Sa, Sz), ZC at the pontic (Sa,Sz) and LW at the connector (Sa). Grinding defects were identified in all systems, especially at regions with elaborative milling.
Conclusions: The Y-TZP destabilizing m-ZrO2 phase was identified in all the fully-sintered frameworks tested, with the highest %Vm located at the margins. Differences were found in roughness parameters among the regions and materials tested not correlated with the distribution of the m-ZrO2 phase. Milling-induced defects were identified in all specimens.