Effect of staining and repeated firing on the surface and optical properties of lithium disilicate

Abstract

Objective: Evaluate the effect of staining and repeated firings on color, translucency and surface proprieties of CAD/CAM lithium disilicate (LD).Material and Methods: One hundred eighty LD discs were made (ISO 6872) and distributed in different groups (n = 20): control (CO)-no treatment; single-step characterization (SC)-crystallization and staining fired together; and double step characterization (DC)-crystallization and then staining. The samples were submitted to two, four, or six firings, resulting in nine groups: COII, COIV, COVI, SCII, SCIV, SCVI, DCII, DCIV, and DCVI. The color and translucency were measured by a reflectance spectrophotometer. Surface roughness (Ra) and Vickers nano-hardness were also measured. ANOVA and Tukey statistical tests were used (α = .05). Results:Only CO and DC demonstrated significant color alterations (ΔE 00 > 1.8). SC and DC did not show changes in translucency by the number of firings (P > .05); however, for CO (P = .02) these values increased. Nano-hardness was similar in all groups (P > .05). Ra values indicated differences due to the type of characterization (SC presented the highest values) and number of firings (CO and DC groups) (P < .01).Conclusion: SC promoted color, translucency, and roughness stability after repeated firings.Clinical Significance: The single characterization technic in CAD/CAM lithium disilicate presents good color, translucency, and hardness stability, which promote predictable results to monolithic restoration. K E Y W O R D Scolor, lithium disilicate, repeated firing, roughness, translucency

Microstructural considerations for novel lithium disilicate glass ceramics: A review

“…39 For this reason, if characterization of the monochromatic LDC is desired, a single characterization technique is recommended. 40 The translucency is controlled by the nano-structure and size of the crystals. 41 Some systems offer up to four levels of translucency:…”

“…Repeated firing of LDC can change translucency and surface properties 39 . For this reason, if characterization of the monochromatic LDC is desired, a single characterization technique is recommended 40 …”

Effect of Consecutive Firings on the Optical and Mechanical Properties of Silicate and Lithium Disilicate Based Glass‐Ceramics

“…In addition to well‐known lithium disilicate, new lithium silicate ceramics containing 10% of zirconia dioxide were developed 17,18 . Porosities, crystallinity degree and crystal organization can be changed by thermal treatments, impacting the color and strength of glass‐ceramics 19,20 . Although laboratory procedures such as additional firings have been investigated, further investigations for lithium disilicate materials have been performed with evidence that it may affect the color parameters 21,22 .…”

Effect of staining on the mechanical, surface and biological properties of lithium disilicate

“…The effect of biodegradation on roughness was noticed as the Ra values of NO- ctrl and SG- ctrl were similar, but NO- bi presented lower Ra values than SG- bi . Such effect could be explained by both the amount and size of crystals in the stain/glaze and in the LD ceramic ( Vo et al, 2015 , Miranda et al, 2020b ), and the fabrication method; while NO samples were produced by machining, SG samples received additional hand application of stain and glaze, which may have resulted in an irregular and porous surface with macroscopic defects ( Vo et al, 2015 , Miranda et al, 2020b , De Jager et al, 2000 , Sun et al, 2016 , Hmaidouch et al, 2014 ).…”