Zirconia crown with cracks, symbolizing LTD.

Is Your Zirconia Crown Safe? The Truth About Glazing and Long-Term Wear

Elliot Brynn in Health & Wellness December 2025 • 4 min read.

"Discover how glazing impacts the flexural strength of translucent zirconia crowns and what it means for your dental health."

In modern dentistry, yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) has become a popular alternative to metal alloys due to its superior light permeability and biocompatibility. This material integrates well with soft tissues and boasts exceptional mechanical and physical properties.

Early Y-TZP products were primarily used as frameworks for anterior and posterior teeth, often layered with a veneering ceramic. These restorations, however, were prone to chipping due to the cohesive failure of the veneering ceramic layer. As a solution, translucent monolithic Y-TZP products have been developed, offering better aesthetics and eliminating the need for a ceramic veneer. These crowns also require less tooth removal, preserving more of your natural tooth structure while ensuring optimal function and aesthetics.

However, the long-term performance of dental zirconia is a topic of ongoing research, particularly concerning low-temperature degradation (LTD), a process that can affect the material’s structural integrity over time. Surface glazing is a common technique used to enhance the aesthetic appeal of zirconia crowns, but questions remain about how this process, combined with LTD, influences the material's flexural strength—its ability to withstand bending forces without fracturing.

Understanding Flexural Strength and Zirconia Crowns

Zirconia crown with cracks, symbolizing LTD.

Flexural strength is a critical property for dental crowns, as it indicates how well a crown can withstand the forces of chewing and biting. Zirconia, known for its high flexural strength, is often chosen for dental restorations because of its durability. However, the flexural strength of zirconia can be affected by several factors, including the manufacturing process, surface treatments like glazing, and environmental conditions within the mouth.

A key concern is low-temperature degradation (LTD), a phenomenon that occurs when zirconia is exposed to moisture and heat over extended periods. This can lead to phase transformations within the material, potentially reducing its strength and increasing the risk of fracture. Given these factors, understanding how glazing and LTD interact to affect the flexural strength of translucent zirconia is essential for ensuring the longevity and reliability of zirconia crowns.

Glazing: A surface treatment applied to enhance aesthetics.
Low-Temperature Degradation (LTD): A process that can weaken zirconia over time.
Flexural Strength: The ability of a crown to withstand bending forces.

A recent in vitro study published in The Journal of Prosthetic Dentistry investigated the effects of surface glazing and LTD on the flexural strength of translucent zirconia. The study aimed to assess whether glazing, intended to improve aesthetics, and LTD, a known degradation process, would compromise the structural integrity of monolithic zirconia crowns.

The Bottom Line: What This Means for Your Dental Work

For patients considering or already having translucent zirconia crowns, understanding the balance between aesthetics and long-term durability is key. Glazing can enhance the appearance of your crown, but it's important to be aware of its potential impact on flexural strength. While LTD remains a concern, ongoing research helps refine our understanding and improve the performance of zirconia restorations. Consulting with your dentist about the best surface treatments and maintenance practices will ensure the longevity and safety of your zirconia crowns.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.prosdent.2018.07.017, Alternate LINK

Title: Changes In The Flexural Strength Of Translucent Zirconia Due To Glazing And Low-Temperature Degradation

Subject: Oral Surgery

Journal: The Journal of Prosthetic Dentistry

Publisher: Elsevier BV

Authors: Min-Gyeong Nam, Mi-Gyoung Park

Published: 2018-12-01

Everything You Need To Know

What is Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP), and why is it used in dental crowns?

Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) is a strong and biocompatible material, making it a popular choice for dental crowns. It's favored for its light permeability, which allows it to blend well with natural teeth, and its ability to integrate with soft tissues. The use of Y-TZP in modern dentistry is a significant shift from metal alloys, offering improved aesthetics and better integration with the body.

What is low-temperature degradation (LTD), and why is it a concern for zirconia crowns?

Low-temperature degradation (LTD) is a process that can weaken zirconia crowns over time. It occurs when zirconia is exposed to moisture and heat, leading to phase transformations within the material. This degradation can reduce the flexural strength of the crown, increasing the risk of fracture. Understanding LTD is crucial because it can compromise the durability of the crown, which can affect its long-term performance and requires more maintenance.

What is flexural strength, and why is it important for dental crowns?

Flexural strength is the ability of a dental crown to withstand bending forces without breaking. This is a critical property for zirconia crowns, as they are subjected to significant forces during chewing and biting. Zirconia's high flexural strength is one of the reasons it's chosen for dental restorations. Factors like manufacturing processes, surface treatments such as glazing, and environmental conditions inside the mouth can influence the flexural strength of the crown, affecting its ability to function properly over time.

How does glazing affect the performance of zirconia crowns?

Glazing is a surface treatment applied to zirconia crowns to enhance their appearance. While glazing can improve aesthetics, it may affect the flexural strength of the crown. The interaction between glazing and low-temperature degradation (LTD) can influence how well a zirconia crown stands up to the forces in the mouth. This balance is essential for the long-term durability and reliability of zirconia crowns, so patient and dentist need to consider this when choosing treatment options.

What are the key considerations for someone with a zirconia crown?

For individuals with translucent zirconia crowns, understanding the potential impact of glazing and LTD on long-term durability is essential. Glazing improves aesthetics but may affect flexural strength. While LTD remains a concern, ongoing research helps improve the performance of zirconia restorations. Consulting with your dentist about the best surface treatments and maintenance practices will ensure the longevity and safety of your zirconia crowns.