Blog

The Era of Digital Aesthetics Has Begun

With the advent of digital dentistry, the range of materials available for aesthetic restorations has increased. The definition of "dental crowns" has expanded to incorporate innovative materials, including zirconia and E.max (lithium disilicate glass-ceramic), rather than being confined to conventional metal-supported porcelains.

Both materials, owing to their metal-free composition, light translucency, and biocompatibility, yield outcomes that closely resemble the natural appearance of teeth. However, there are some fundamental differences in terms of indications, durability, and aesthetic performance.

In this review, zirconia and E.max systems are compared based on their clinical applicability, aesthetic performance, and material properties.

Zirconia Crowns: Strong, Durable, and Versatile

a. Structural Properties

• Zirconia (ZrO₂) is a material used in dentistry in the form of oxide ceramics.
• It is as strong as metal and as aesthetic as porcelain.
• Although its light translucency is more limited compared to conventional ceramics, this difference has been largely minimized with the “translucent zirconia” series.

b. Advantages

• High strength: With a compressive strength of 900–1200 MPa, it is highly resistant to posterior masticatory forces.
• Metal-free: Eliminates the risk of allergic reactions.
• Long-Lasting: Provides a lifespan of approximately 10–15 years with proper maintenance.
• Excellent gingival compatibility: Does not cause discoloration or gingival pigmentation.
• Suitable for fixed partial dentures: Ideal for bridge restorations.

c. Disadvantages

• Light translucency is slightly lower compared to E.max.
• May appear relatively opaque in patients seeking "highly natural" aesthetics in the anterior region.
• Shade selection depends on the laboratory proficiency.

d. Indications

• Posterior teeth (high occlusal force)
• Dental bridges
• Implant-supported crowns
• Bruxism

According to data published in the Journal of Prosthetic Dentistry (2021), the fracture rate of zirconia crowns was reported to be only 2.3% over a 5-year period.

E.max Crowns: Maximized Translucency- the Hallmark of Natural Aesthetics

a. Structural Properties

E.max is a lithium disilicate glass-ceramic-based material. It has a durability of approximately 400 MPa—although it is more brittle than zirconia, it is significantly more aesthetic.

Its translucency makes it the material closest to natural teeth. Therefore, it is preferred for "smile designs" and anterior esthetic restorations.

b. Advantages

• High Aesthetic Value: It perfectly mimics the natural translucency and luster of teeth.
• Shade matching: Minimal risk of shade discrepancy with adjacent teeth.
• Metal-free and biocompatible.
• Minimal tooth preparation is sufficient, resulting in less loss of tooth structure.

c. Disadvantages

• May not withstand excessive occlusal forces in posterior regions.
• Not suitable for long-span bridges (maximum of three units).
• Fracture risk is higher in teeth affected by bruxism.

d. Indications

• Anterior aesthetic restorations (laminates, veneers, single-unit crowns)
• Smile design procedures
• Cases requiring shade correction following teeth bleaching

According to the European Journal of Esthetic Dentistry (2020), patient satisfaction with E.max restorations was reported at 96%, while shade matching success was 92%.

Not Every Tooth Requires the Same Material

In aesthetic dentistry, there is no "best material," only the "most suitable material." While Zirconium provides confidence through its durability, E.max dazzles with its natural appearance. The dentist's aesthetic vision, laboratory quality, and the patient's expectations are the primary factors that determine the outcome.

With appropriate clinical indications, both materials yield durable outcomes that closely mimic the sensation of natural dentition.