Color stability of fully- and pre-crystalized chair-side CAD-CAM lithium disilicate restorations after required and additional sintering processes

Abstract

PURPOSE The aim of this study was to investigate shade changes in fully- and pre-crystalized CAD-CAM lithium disilicate crowns after the required and additional firing processes. MATERIALS AND METHODS One hundred and five crowns of shade A1 with high translucency were milled out of CAD-CAM lithium disilicate blocks and categorized as follows (n = 15): (1) restorations fabricated from Straumann n!ce with no additional sintering process; (2) restorations fabricated from Straumann n!ce with one additional sintering process; (3) restorations fabricated from Straumann n!ce with two additional sintering processes; (4) restorations fabricated from Amber Mill with one sintering process; (5) restorations fabricated from Amber Mill with two sintering processes; (6) restorations fabricated from IPS e.max CAD with one sintering process; (7) restorations fabricated from IPS e.max CAD with two sintering processes. All restorations were evaluated with a color imaging spectrophotometer. RESULTS All restorations presented some color alteration from the original shade both after a single and after two firing processes. CONCLUSION The required and additional sintering processes for restorations fabricated with chairside CAD-CAM lithium disilicate blocks cause an alteration of the original shade selected. Shade A1 high translucency restorations tend to change to a more yellowish B1 shade after a sintering process.

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

“…The authors of [ 19 ] have concluded that NLD had color stability either similar to or higher than LDS, while the color change in both materials was unacceptable regardless of the resin cement shade. In another study, LDS was found to maintain its shade after required and additional crystallization, whereas NLD differed from its original shade even after the first crystallization firing [ 16 ]. Considering the novelty of NLD and the fact that the present study is the first to address the comparison of NLD and ZLS in terms of color stability, these findings need to be substantiated.…”

“…Recently, a new lithium disilicate called nano-lithium disilicate glass-ceramic (NLD; Amber Mill, Hass, Gangneung, Korea) has been marketed [ 7 , 8 , 12 ]. 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 ].…”

“…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.…”

Ceramic and Composite Polishing Systems for Milled Lithium Disilicate Restorative Materials: A 2D and 3D Comparative In Vitro Study

“…Dental treatments with CAD/CAM technology can fulfill patient esthetic demands from single to multiple ceramic restorations [ 10 , 11 ]. Lithium disilicate is a well-known dental ceramic with high esthetics and fracture resistance [ 12 , 13 ].…”