With the wide variety of high-strength, tooth-colored dental crown materials available in dentistry today, it’s easy to be overwhelmed by the differences in indications and benefits of each solution. At Glidewell we field questions from tens of thousands of dental professionals on a weekly basis, and one common question is, “What’s the difference between zirconia crowns and IPS e.max^® crowns?”

While both are very popular monolithic restorative options, zirconia crowns and IPS e.max crowns have key differences that define when and how they can be used. Continue reading to see how they compare in terms of performance, appearance, preparation requirements and indications.

Zirconia crowns are dental restorations made from zirconium oxide, which is a ceramic oxide used throughout many industries for high-strength, biocompatible applications. It has a proven history of use in health care settings since the 1970s, and came into popular use in dentistry in the early 2000s, first for copings and then later for full-contour crowns and bridges.

Zirconia crowns are among the strongest tooth-colored restorative options available in dentistry. In the United States, they’ve been used broadly for clinical situations that previously would have required full-cast gold restorations, such as patients who have forceful bites, patients who clench and grind, or in areas with limited space.

At Glidewell, we offer two primary types of zirconia crowns: BruxZir^® Full-Strength Zirconia and BruxZir Esthetic Zirconia. BruxZir Full-Strength offers exceptionally high strength and has demonstrated survival against the toughest clinical forces. BruxZir Esthetic offers a more true-to-life appearance than the full-strength version at the cost of some of its strength; however, it is still a very durable material. Monolithic zirconia can be used for virtually all types of indications, from single units all the way up to full-arch prostheses.

IPS e.max crowns are dental restorations made from lithium disilicate, a glass-ceramic material that’s composed of quartz, lithium dioxide, phosphor oxide, alumina, potassium oxide and other components. This combination results in crowns with excellent esthetics that are simple to use in the dental practice. What’s more, according to Ivoclar Vivadent, IPS e.max is the world’s best-selling glass-ceramic dental material.¹ IPS e.max lithium disilicate can be used for single-unit restorations as well as anterior bridges up to 3 units.

When comparing the performance of monolithic ceramic materials, the most commonly discussed characteristic is flexural strength.

Flexural strength is a measure of a material’s ability to withstand an impacting force prior to breaking. In a clinical setting, this influences how much bite stress can be applied to a crown before failure. Flexural strength also influences a material’s ability to be made into long-span bridges as well as the overall wall thickness of the final restoration. Ceramic materials with greater flexural strength typically support versatility and minimally invasive dentistry.²

Zirconia crowns exhibit a higher flexural strength value than IPS e.max crowns, indicating that zirconia crowns are more likely to perform better in clinical situations that demand toughness.

While zirconia crowns are stronger, both BruxZir and IPS e.max restorations have demonstrated excellent performance in a 10-year independent clinical study. In the study published by the Gordon J. Christensen Clinicians Report^®, 100% of BruxZir Full-Strength crowns and 94% of IPS e.max crowns survived after 10 years of clinical service.⁵ Both options represent a substantial strength and performance increase over the PFM restorations that have been commonly used in dentistry during the last few decades.

One of the biggest challenges in restorative dentistry is precisely matching a ceramic restoration to the surrounding natural dentition. To help dentists, material manufacturers have gone to great lengths to develop options that exhibit light transmission, reflection and color characteristics similar to real teeth, with each generation of restorative material offering improved appearances. Zirconia and IPS e.max crowns represent the latest generation of restorative materials available in dentistry, and they both benefit from advanced manufacturing techniques.

Over the last decade in dentistry, IPS e.max crowns have been widely recognized as some of the most beautiful monolithic ceramic restorations available. They have a coloration and translucency that closely matches those of natural dentition. As a result, IPS e.max crowns are used very commonly for treatment in the smile zone.

As a byproduct of their high-strength composition, zirconia crowns allow for less light transmission than their lithium disilicate counterparts. The reduced light transmission results in a less vital-looking restoration. While their zirconia composition does impact the overall appearance, this has been addressed substantially in recent years. The full-strength zirconia crowns of today exhibit an enhanced appearance compared to the original monolithic zirconia restorations released in 2009. And, when compared to many other zirconia crown brands, BruxZir Full-Strength crowns have enhanced optical properties thanks to their patented composition. Still, zirconia crowns are most commonly used for treatment in the posterior of the mouth.

Recently, an additional class of zirconia crown has been introduced that offers an even more improved appearance while still maintaining substantial strength. At Glidewell, we offer BruxZir Esthetic, which has more true-to-life coloration and translucency characteristics than classic full-strength zirconia. First launched in 2018, BruxZir Esthetic crowns are quickly becoming a favorite among dentists for anterior cases.

The specific strength and optical characteristics of IPS e.max and zirconia result in each material being best suited for different types of restorations.

BruxZir Full-Strength is extremely versatile. It can be used for crowns, bridges up to 16 units, veneers, inlays and onlays, screw-retained crowns and bridges, and full-arch implant prostheses. What’s more, BruxZir Full-Strength restorations only require 0.5 mm of reduction, although 1.0 mm is ideal.

IPS e.max is ideal for single crowns, inlays, onlays, veneers and anterior bridges up to 3 units. Crowns made from lithium disilicate require a minimum of 1.0 mm of reduction, but 1.5 mm reduction is recommended for the incisal or occlusal third.

BruxZir Esthetic again splits the difference between lithium disilicate and full-strength zirconia crowns. Per ISO 6872:2015/AMD 1:2018, the internationally recognized indication-specific strength recommendations for dental ceramics, materials require over 800 MPa to be used for four or more units. While lithium disilicate materials do not meet this requirement, BruxZir Esthetic exhibits 870 MPa and thus can be used safely for a wide range of indications. BruxZir Esthetic is great for anterior and posterior single-unit crowns, anterior bridges up to 6 units, posterior bridges up to 4 units, screw-retained crowns, veneers, inlays and onlays, and full-arch implant prostheses. Plus, BruxZir Esthetic restorations only require 0.7 mm of reduction, though 1.25 mm is ideal.

Here, we’ve included brief summaries of each of the materials discussed above:

Full-strength zirconia crowns are substantially stronger than lithium disilicate restorations. They allow for less reduction on the preparation and can be used for a broader range of indications, while still having a patient-pleasing appearance. Zirconia crowns are ideal for scenarios that require the highest levels of toughness as well as for patients who desire lasting function.

IPS e.max restorations offer leading esthetics for the anterior, with coloration and translucency that closely matches that of natural teeth. However, they are not as strong as monolithic zirconia materials and have a more limited range of indications. IPS e.max crowns are ideal for anterior cases that require a premium level of esthetics and for patients who must have a “Hollywood smile.”

The anterior-minded BruxZir Esthetic zirconia crowns offer a middle ground, with strength values between those of IPS e.max and BruxZir Full-Strength crowns and a true-to-life appearance that’s certain to wow most patients. BruxZir Esthetic crowns are ideal for patients that require both lasting toughness and lifelike beauty.

We hope that this information provides additional insight for dental professionals who are deciding between the use of zirconia crowns and IPS e.max crowns. Ultimately, dentists must rely on their own expertise and experience to determine which solution works best for a specific patient. Rest assured that for many of dentistry’s routine restorative cases, BruxZir and IPS e.max restorations are proven to be excellent choices.