Lithium Disilicate
A Visual Deep Dive into Dentistry’s High-Performance Ceramic
The Benchmark of Strength
Lithium disilicate sets the standard for dental restorations, combining aesthetic beauty with exceptional durability. Advanced formulations push the boundaries of material science, delivering performance far beyond traditional ceramics.
Its unique crystal structure provides inherent resistance to fractures, ensuring longevity even under the high-stress conditions of the posterior mouth.
(Advanced Formulations)
Engineered Microstructure: The Source of Power
Lithium disilicate is a glass-ceramic defined by its dual-phase composition. Its strength doesn’t come from a single material, but from a synergistic blend of a glassy matrix and a high volume of densely packed crystals.
This interlocking network of needle-like crystals is the key to its success. It creates a microscopic reinforcement that actively stops cracks from propagating, a mechanism known as crack-tip deflection. This intrinsic toughness is what separates it from more brittle, traditional porcelains.
A Spectrum of Strength
Not all lithium disilicate is created equal. The fabrication method and specific formulation dramatically impact its final mechanical properties. Hot-pressed versions typically exhibit higher strength than milled counterparts, while advanced formulations significantly outperform standard options.
Two Paths to Perfection: Fabrication Workflow
1. Hot-Pressing Technique
A detailed wax model of the restoration is created.
The wax is encased in investment material and burned out to create a mold.
A fully crystallized ingot is heated (~920°C) and pressed into the mold.
Outcome: Superior strength (400+ MPa) and fracture toughness due to optimized crystal growth.
2. CAD/CAM Milling Technique
The tooth is scanned and the restoration is designed digitally.
A “blue block” (soft, partially crystallized) is milled into shape.
The milled crown is heated (~850°C) to achieve final strength and aesthetics.
Outcome: Exceptional speed (single-visit potential) and high precision with good strength (~360 MPa).
Proven Clinical Longevity
In the demanding oral environment, lithium disilicate has an outstanding track record. Numerous long-term studies demonstrate high survival rates, often exceeding 95% over many years of function. Its durability is not just a lab measurement; it’s a clinical reality.
Failures, when they do occur, are more commonly linked to cementation issues rather than a fracture of the material itself, highlighting its intrinsic resilience.
Kind to Natural Teeth
A restoration’s impact on opposing teeth is a critical factor for long-term oral health. When properly polished, lithium disilicate is remarkably gentle on natural enamel, causing significantly less wear than older ceramic materials like feldspathic porcelain.
This property helps preserve the patient’s natural dentition, making it a biocompatible choice that integrates harmoniously into the occlusal system.
The All-Round Performer
How does lithium disilicate stack up against its main competitor, Zirconia? While Zirconia boasts higher raw strength, lithium disilicate often wins on aesthetics and bondability, creating a more balanced profile for a wider range of clinical needs, especially in the anterior.
Aesthetic Versatility: Controlling Light
One of the greatest advantages of lithium disilicate is the ability to control its translucency. It is available in multiple levels of opacity, allowing clinicians to either let the color of the underlying tooth show through for a natural blend or block it out to mask discoloration.
HT
High Translucency
MT
Medium Translucency
LT
Low Translucency
MO
Medium Opacity
HO
High Opacity