J Dent. 2024 Jul 21:105257. doi: 10.1016/j.jdent.2024.105257. Online ahead of print.
ABSTRACT
OBJECTIVE: Evaluate the impact of a “fast” crystallization and simultaneous-glazing on the physicochemical properties of lithium-disilicate CAD/CAM-ceramic.
METHODS: Lithium-disilicate bars and crowns (IPS e.max CAD, Ivoclar-Vivadent) were divided into four groups (n=30): WG/F (WG=with glaze/F=fast crystallization), NG/F (NG=no glaze), WG/C (C=conventional crystallization), and NG/C. A liquid/powder glaze system was used (IPS Ivocolor®, Ivoclar-Vivadent). Specimens were crystallized (Programat P310, Ivoclar-Vivadent) using the P161 program for C (approx. 20-25min), and P165 for F (approx. 14-16min). Bars (n=30) underwent three-point bending tests (flexural strength-FS in MPa and modulus of elasticity-E in GPa) using a universal testing machine. Crowns were analyzed via scanning electron microscopy (SEM) after selective etching, and to Raman, FTIR-ATR, and X-ray diffraction (XRD) spectroscopies to assess chemical composition.
RESULTS: For FS, both factors/interaction were statistically significant. C (427.48±42.41MPa) showed significantly higher values than F (409.82±38.82MPa). WG (398.32±29.80MPa) exhibited significantly lower FS than NG (438.21±41.77MPa). For E data, both factors/interaction were significant. NG (90.28±14.71GPa) displayed higher E than WG (83.07±5.69GPa), while C (90.08±12.98GPa) exhibited higher E than F (83.46±9.40GPa). NG/C showed the best results for both variables. F groups showed (SEM) porous surfaces and crack-like marks on crystals. FTIR, Raman and XRD spectra confirmed the typical composition of a lithium-disilicate glass ceramic, and some attenuated signals and structural variations (XRD) in WG.
CONCLUSIONS: “Fast” crystallization and simultaneous-glazing produced weaker/less-rigid structures with irregular crystals and glassy phases. Simultaneous glazing may have hindered proper thermal distribution during crystallization.
SIGNIFICANCE: “Fast” crystallization and simultaneous glazing with non-recommended systems, can adversely affect the final properties of lithium disilicate restorations.
PMID:39043330 | DOI:10.1016/j.jdent.2024.105257
