Characterization of Lithia-Based Machinable Glass-Ceramic Materials

Area of Science:

• Dental materials science
• Ceramic engineering
• Biomaterials

Background:

• Lithia-based glass ceramics dominate indirect single-unit restorations.
• Existing evidence primarily focuses on a single material, necessitating broader investigation.
• Recent advancements have introduced new lithia-based glass-ceramic materials.

Purpose of the Study:

• To comprehensively evaluate diverse lithia-based glass ceramics.
• To investigate elemental and elemental oxide composition.
• To assess as-fabricated surface morphology, flexural strength, color, contrast ratio, and light transmission.

Main Methods:

• Analysis of nine dental materials (Amber Direct, Amber Mill, Cerec Tessera, IPS Emax CAD, Enamic, IPS Empress CAD, Initial Lisi, Supriniy PC, TriLuxe Forte).
• Utilized techniques: Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES), X-ray Fluorescence (XRF), Scanning Electron Microscopy (SEM).
• Evaluated mechanical strength, visible light spectroscopy, and transmission testing, with statistical analysis (ANOVA, multiple comparisons) at α=0.05.

Main Results:

• Significant variations observed in chemical composition, physical properties, and optical characteristics among tested lithia-based glass ceramics.
• Milling partly crystallized blocks followed by additional crystallization nearly doubled flexural strength compared to milling fully sintered blocks.
• Color parameters varied significantly, exceeding visual detection thresholds despite nominal shade matching.

Conclusions:

• Diverse lithia-based glass-ceramic materials exhibit substantial differences in chemical composition, strength, and optical properties.
• These variations are significant enough to impact clinical performance.
• Optimized processing, specifically milling partially crystallized blocks, enhances flexural strength and minimizes machining damage, suggesting improved clinical outcomes.