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

Abstract

The aim of this study was to compare the load-to-failure resistance and optical properties of nano-lithium disilicate (NLD) with lithium disilicate (LDS) and zirconia-reinforced lithium silicate (ZLS) in different aging processes. Thirty crowns were milled from NLD, LDS, and ZLS (n = 10). All crowns were subjected to thermomechanical aging and loaded until catastrophic failure. Ten specimens from each material were prepared in two different thicknesses (0.7 mm and 1.5 mm, n = 5), and color coordinates were measured before and after coffee thermocycling. Color differences (ΔE00) and relative translucency parameter (RTP) were calculated. Data were analyzed by using ANOVA and Bonferroni-corrected t-tests (α = 0.05). ZLS had the highest load-to-failure resistance (p ≤ 0.002), while the difference between LDS and NLD was nonsignificant (p = 0.776). The interaction between material type and thickness affected ΔE00 (p < 0.001). Among the 0.7 mm thick specimens, ZLS had the lowest ΔE00 (p < 0.001). Furthermore, 1.5 mm thick ZLS had lower ΔE00 than that of 1.5 mm thick LDS (p = 0.036). Other than ZLS (p = 0.078), 0.7 mm thick specimens had higher ΔE00 (p < 0.001). The interaction between material type, thickness, and thermocycling affected RTP (p < 0.001). Thinner specimens presented higher RTP (p < 0.001). NLD and LDS had higher RTP than ZLS (p ≤ 0.036). However, 0.7 mm thick specimens had similar RTP after coffee thermocycling (p ≥ 0.265). Coffee thermocycling reduced the RTP values of 0.7 mm thick NLD (p = 0.032) and LDS (p = 0.008). NLD may endure the occlusal forces present in the posterior region. However, long-term coffee consumption may impair the esthetics of restorations particularly when thin NLD is used.

Translucency, color stability, and biaxial flexural strength of advanced lithium disilicate ceramic after coffee thermocycling

“…Even though BFS tests were in line with ISO 6872:2015 standards, 31 color coordinate measurements were performed with a spectrophotometer that was used to evaluate the optical properties of CAD-CAM ceramics, 15 and ΔE 00 and RTP values were calculated similar to previous studies, 4,16,25,28 the results of the present study should be carefully interpreted. CIEDE2000 formula was used in the present study with the parametric factors set as 1.…”

“…A digital spectrophotometer (CM‐26d; Konica Minolta) 15 was used for color coordinate ( L *, which corresponds to lightness; a *, which corresponds to redness; b *, which corresponds to yellowness) 13,29,32 measurements. This spectrophotometer has a diffused illumination integrating sphere system (8° viewing) and two specular component modes (specular component included and excluded).…”

“…2,6,7 Even though lithium disilicate glass ceramic has increased its popularity significantly ever since and became the material of choice compared with other glass-matrix ceramics, 8 new materials are frequently marketed. [9][10][11] Zirconia-reinforced lithium silicate glass ceramic (ZLS) has been launched as a unique material that combines the advantages of lithium disilicate and zirconia [12][13][14][15][16] due to 10 wt% of zirconium dissolved in its glassy matrix. 17 Currently, ZLS is available either in crystallized (Celtra Duo; Dentsply Sirona) or pre-crystallized form (Vita Suprinity; Vita Zahnfabrik).…”

Optical properties, biaxial flexural strength, and reliability of new‐generation lithium disilicate glass‐ceramics after thermal cycling

“…Studies on nano‐lithium disilicate 6,9–15 and fully crystallized lithium disilicate 6,16 glass–ceramics are scarce. To the authors’ knowledge, optical properties of fully crystallized lithium disilicate have not been investigated, whereas only three studies on nano‐lithium disilicate 9,10,12 have focused on this aspect.…”

“…Studies on nano‐lithium disilicate 6,9–15 and fully crystallized lithium disilicate 6,16 glass–ceramics are scarce. To the authors’ knowledge, optical properties of fully crystallized lithium disilicate have not been investigated, whereas only three studies on nano‐lithium disilicate 9,10,12 have focused on this aspect. Therefore, the present study aimed to compare the color stability, translucency, and biaxial flexural strength (BFS) of two newly introduced lithium disilicate glass–ceramics (nano‐lithium disilicate and fully crystallized lithium disilicate) with those of a commonly used lithium disilicate glass–ceramic.…”