Yttria-stabilized zirconia (YSZ) has emerged as a leading material for dental restorations due to its exceptional biocompatibility and superior mechanical properties compared to traditional options. However, despite ongoing research since its commercialization, mechanical properties can be improved. The persistence of interstitial voids resulting from pressing methods remains a challenge, given the powder technology process used to manufacture zirconia blocks, which involves powder mixing, pressing, and sintering steps. In terms of pristine powder, the improvements involve mitigating defects associated with persistent inter- and intra-granulate interstitial voids. Additionally, the current commercial multilayer zirconia, composed of blocks containing 3-5 mol% of yttria-stabilizer (3YSZ-5YSZ), holds promising potential in terms of esthetics. However, limited knowledge exists regarding its mechanical properties due to constraints in testing standards and methodologies for multilayer configuration. To address these limitations, this study aimed to alter the granule size distribution of 3YSZ and 5YSZ commercial powder as a strategy to achieve denser particle packing, thereby reducing the occurrence of strength-limiting pressing defects. Additionally, bilayer specimens were produced in-house to investigate the interface between layers and its impact on mechanical properties and reliability. The partitioning of powder-size distribution was carried out to modify granule size distribution, aiming to minimize pressing defects post-dry pressing through increased packing density. Furthermore, to address difficulties in sectioning multilayer blocks precisely, this work proposed the development of bilayer specimens mirroring the manufacturing configuration of original blocks using 3YSZ and 5YSZ composition zirconia as a base. The study, centered around commercially available materials 3YSZ and 5YSZ, encompassed various processes such as sieving, mixing powders, laser diffraction for granule size distribution analysis, and sintering techniques. Characterization techniques including X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM) were employed for phase identification and quantification, while residual stress was assessed using Raman spectroscopy. Mechanical properties evaluation involved biaxial bending tests, uniaxial flexural strength tests, fracture toughness assessments, and stair-case fatigue strength tests. Additionally, hydrothermal aging treatment was conducted on bilayer specimens to investigate mechanical property changes.