Evaluation of the Milling Accuracy of Zirconia-Reinforced Lithium Silicate Crowns Fabricated Using the Dental Medical Device System: A Three-Dimensional Analysis

Abstract

This study aimed to analyze the milling accuracy of lithium disilicate and zirconia-reinforced silicate crown fabricated using chairside computer-aided design/manufacturing (CAD/CAM) system. Mandibular left first premolar was selected for abutment. A master model was obtained for digital impression using an intraoral scanner, and crowns were designed using a CAD software design program. Amber Mill (AM), IPS e max CAD (IPS), and CELTRA DUO (CEL) were used in the CAD/CAM system, and a total 45 crowns (15 crowns each for AM, IPS, and CEL) was fabricated. Milling accuracy was analyzed with respect to trueness, measured by superimposing CAD design data and scan data through a three-dimensional program to compare the outer and inner surfaces and internal and external parts, thereby acquiring both quantitative and qualitative data. Data were analyzed using the non-parametric test and Kruskal–Wallis H test. In addition, the Mann–Whitney U test was used by applying the level of significance (0.05/3 = 0.016) adjusted by post-analysis Bonferroni correction. All the measured parts of the lithium disilicate and zirconia-reinforced silicate crowns showed statistically significant differences (p < 0.05). The lithium disilicate (AM and IPS) materials showed superior milling accuracy than the zirconia-reinforced lithium silicate (CEL) materials.

Load-to-Failure Resistance and Optical Characteristics of Nano-Lithium Disilicate Ceramic after Different Aging Processes

“…Previous studies have investigated NLD’s different mechanical properties [ 7 , 17 , 18 , 20 ]. Yin et al [ 20 ] have reported that NLD had higher Vickers hardness and biaxial flexural strength values, along with a more stable surface topography than CAD-CAM composite blocks.…”

“…A recent study has investigated the fracture toughness of lithium silicate ceramics and concluded that NLD had higher values than ZLS [ 7 ]. Kang et al [ 18 ] showed that NLD and LDS have similar milling accuracy that was higher than that of ZLS. Considering the results of the present and those previous studies on NLD, it can be speculated that NLD might be a favorable material mechanically, but this hypothesis should be substantiated with future in vivo studies.…”

“…NLD differs from currently available lithium silicate ceramics, as its translucency is adjustable depending on the crystallization process [ 16 ]. Even though NLD has started to gain attention, the number of studies on this material is scarce [ 7 , 12 , 16 , 17 , 18 , 19 , 20 ].…”

“…However, considering the chemical differences among different lithium silicate glass-ceramics [ 7 ], clinicians would benefit from studies that report performance differences among these materials. In addition, the existing studies on NLD [ 7 , 12 , 16 , 17 , 18 , 19 , 20 ] did not investigate its fracture resistance, and only three studies have focused on its optical properties, which did not involve aging [ 12 , 16 , 19 ]. Therefore, this study aimed to compare NLD with LDS and ZLS in terms of load-to-failure resistance, color stability, and translucency after aging.…”

A Comparative Study of Additive and Subtractive Manufacturing Techniques for a Zirconia Dental Product: An Analysis of the Manufacturing Accuracy and the Bond Strength of Porcelain to Zirconia

“…In addition, for zirconia manufactured with the AM technology to be used in dental practice, the zirconia-based dental prosthesis must have micro-level accuracy to ensure a perfect fit with the abutment and prevent secondary caries in the oral cavity. Several studies have evaluated the accuracy of zirconia dental prostheses manufactured with SM technology [ 22 , 23 , 24 ]. Most of these studies have focused on the internal and marginal fitting accuracy between the abutment and crown prepared by SM technology, and the fitting accuracy was better than those of the dental prostheses manufactured via conventional dental technology; however, few studies have focused on the manufacturing accuracy of zirconia dental prostheses based on AM technology.…”