For a long time, I’ve wanted to write about this topic but never had the chance due to my busy schedule. However, since many of you feel confused about choosing between e.max, zirconia, and monolithic zirconia materials, I’d like to share my knowledge with you.
In this article, I will briefly and clearly touch on:
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What zirconia, monolithic zirconia, and e.max are
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Which one is more durable and why
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Which one is more aesthetic and why
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Which material should be preferred in which situations and for what reasons
The increasing demand for materials with superior aesthetics has led to the use of metal-free ceramic systems as alternatives to metal-ceramic restorations. In order to achieve optimal aesthetic results in restorations such as crowns and bridges, the optical properties of the materials used must be similar to those of natural teeth. The most important factor here is translucency, which refers to partial light transmission. A translucent material allows part of the light to pass through, while some is reflected and some absorbed by the material.
The success of a dental restoration depends on many factors related to the selected material, such as its mechanical properties, anatomical form, surface texture, translucency, and color.
What Is Zirconia?
Zirconium is a naturally occurring element. Zirconia is the name given to a material that has been strengthened through various mechanical and chemical processes. Among dental ceramics, zirconia dental framework material, referred to as Y-TZP, is the strongest and hardest. However, traditional zirconia has very low translucency, so when used directly in the mouth it appears too opaque and results in poor color aesthetics. It lacks the ability to transmit, reflect, and absorb light in a way that creates a natural appearance.
To improve the esthetics of traditional zirconia, porcelain layering is often applied over zirconia crowns and bridges. However, this layering can lead to chipping over time.
As an alternative, monolithic zirconia materials—where there is little to no porcelain layering—were developed.
Monolithic Zirconia
Recently, to prevent failures caused by chipping of layered porcelain in crowns and bridges, the production of full-contour zirconia (monolithic zirconia) restorations has become more common. To improve translucency and esthetics, changes have been made in sintering temperature, manufacturing processes, and coloring liquids.
The main clinical advantages of monolithic zirconia are:
Monolithic zirconia has significantly higher fracture resistance than layered or monolithic lithium disilicate restorations. Studies show that monolithic zirconia ceramics are much more resistant to chipping and flexural fracture compared to lithium disilicate (e.max), glass-infiltrated zirconia, and veneering porcelain.
Additionally, well-polished monolithic zirconia causes less wear on opposing natural teeth than glazed veneering porcelain. Therefore, polished monolithic zirconia is more “friendly” to the opposing enamel. It also behaves similarly to or better than natural enamel in terms of brushing wear.
With advancing technology, monolithic zirconia ceramics are now pressed in layers to increase translucency. Retrospective clinical studies show good marginal adaptation and gingival compatibility. They also demonstrate high survival and success rates, especially in implant-supported restorations.
Lithium Disilicate Glass Ceramic (E.max)
In recent years, there have been rapid advancements in both material properties and production techniques in dental ceramics. Glass ceramics have become preferred due to their high esthetics and acceptable mechanical properties in the oral environment.
These materials are available either as CAD/CAM millable blocks or as pressable ingots using the lost-wax technique.
The main clinical advantages of lithium disilicate glass ceramics are:
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Not as strong as monolithic zirconia, but suitable for single-unit restorations
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Much better color and optical properties than monolithic zirconia
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Ideal for highly aesthetic restorations in the anterior region
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Very close to natural teeth in light transmission and color
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High success and survival rates in single anterior restorations
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No allergic reactions
Due to all these advantages, lithium disilicate materials like e.max are considered premium and therefore more expensive.
Conclusion
E.max lithium disilicate glass ceramics are more expensive than monolithic zirconia but offer superior aesthetics.
Monolithic zirconia is slightly more affordable and much stronger, making it ideal for complex restorations such as implant-supported prosthetics.
