Effects of Sintering Temperature and Finishing Procedure on Surface Roughness of Different Ytrria Content Zirconia

Introduction: Zirconia-based ceramics have been successfully used to fabricate dental prostheses using the dental Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM) system. Fabrication and finishing of new generation zirconia ceramics is an important issue for the success of restorations. It is necessary to investigate whether these processes affect the surface properties of zirconia materials.

Aim: To investigate the effects of different sintering temperatures and finishing procedures on the surface roughness of zirconia.

Materials and Methods: This in-vitro study was carried out in the Erciyes University Research Laboratory from 7th January to 4th April 2021. Katana Ultra Translucent Multi Layered (KT10; Kuraray Noritake Dental Inc., Tokyo, Japan) and Zolid High Translucent+Preshade (AmannGirrbach AG, Herrschaftswiesen, Austria) were the two types of zirconia materials used in this in-vitro study. Total 40 samples (20 in each group) were produced using the dry program in the I?nLAB MC X5 milling machine (Dentsply Sirona, Bensheim, Germany). Total 20 specimens (10 from each group) were sintered in a furnace for 2 hour at 1450°C and the remaining 20 specimens (10 from each group) were sintered at 1650°C. The two surfaces of the specimens were divided into two groups; one surface of the specimens underwent polishing and the other underwent glazing. A profilometer was used to analyse the surface roughness of the specimens. Three-way analysis of variance was used to assess significant differences in the average roughness values based on the material, sintering temperature, finishing procedure.

Results: The surface roughness values differed between specimens that underwent the glazing and the polishing process at high sintering temperatures. The glazed samples (1.154 µm) had higher surface roughness values than the polished samples (0.808 µm) at 1650°C.

Conclusion: The polishing process is recommended instead of glazing as a finishing procedure for zirconia materials.