Dental Zirconia: What Type Do I Use?

Advancements in dental materials have transformed restorative dentistry, offering practitioners a variety of options to enhance patient outcomes. One such material, zirconia, has gained considerable attention for its durability and aesthetic potential. As the field continues to evolve, understanding the properties and applications of zirconia becomes essential for optimizing restorative techniques. This article explores the current perspectives on dental zirconia, its benefits, and challenges, and provides practical insights for its effective use in dental restorations.

An Overview on Dental Zirconia in Restorations

Recently, in the Restorative Design and Anterior Restorative Dentistry Workshops, we have been entertaining many questions about zirconia and its common use for crowns on posterior (and anterior) teeth. Most dentists use zirconia, especially for restoration of posterior teeth. The main reasons presented by workshop participants are high strength and the resistance to fracture.

The American Dental Association Clinical Evaluators(ACE) obtained a survey recently(2021) from 277 dentists regarding their use of zirconia for restoring tooth structure. In that survey 98% of dentists use zirconia for posterior restorations. Only 61% of those same dentists use zirconia in the anterior region. The advantages and disadvantages listed in that survey are seen in the diagrams below.

The main advantages of zirconia listed by those surveyed were its flexural strength and fracture resistance, just as discussed with workshop participants. The primary disadvantages were restoration removal/replacement, shade matching and translucency variation. Additionally, more than 50% of those same dentists experienced debonding of zirconia restorations.

Even given the significant problems associated with shade matching and debonding, most dentists still prefer zirconia as the indirect restorative material of choice. However, there is one big concern that centers not on dental zirconia use itself, but instead on the dentist’s own understanding of it.

Types of Zirconia and Their Applications

Most dentists do not know what type of zirconia is being used by their dental labs for the construction of their restorations. All zirconia is not the same! It is not all the same strength, and the fracture resistance advantage can be misleading. The various types of zirconia need to be understood and their use applied strategically.

With that said, I went into the literature to examine some research and evidence to identify the types of zirconia, the variation in strengths and recommended uses. My hope is that the dentists within the Spear Digest forum may use this chart as a reference and guide when using zirconia in practice.

3Y Zirconia

Generally speaking, high strength 3Y zirconia is used for posterior crowns, fixed bridge frameworks and implant posts, as the bright white color (high value shade) is unsatisfactory for use in esthetic zones. 3Y is the strongest ceramic used in dentistry.

4Y Zirconia

4Y zirconia is the workhorse of zirconia materials. It can be used in both anterior and posterior situations as crowns, onlays or veneers. This zirconia is both strong and has a translucent appearance that better resembles tooth structure.

5Y Zirconia

5Y zirconia is recommended for use only in anterior veneers or anterior crowns. The strength of 5Y zirconia is greatly diminished due to the additional yttria content. Zirconia strength diminishes with additional yttria, but translucency increases.

Multi-layered zirconia materials

Multi-layered zirconia materials (3Y-5Y; 4Y-5Y) are designed to blend improved appearance with structural durability. However, the occlusal or functional surface aspect translucent layer, which is intended to provide improved esthetics and a more natural appearance, is also the weakest and least fracture resistant. In fact, the results from a recent zirconia fracture resistance study showed that if the material thickness is less than 1.00mm, 70% of the 5Y zirconia samples failed, as compared to zero failures of 3Y zirconia, at the same thickness. Care must be taken when using these materials in demanding functional circumstances.

Communicating with Dental Labs: Ensuring Optimal Outcomes

It is important to understand that not all zirconia is the same. When using zirconia, I recommend a discussion with your dental laboratory technician about what restorative need or intention is anticipated. The type of zirconia used should be selected based upon that objective. Dentists do not need to know all the zirconia manufacturers, but we need to know the zirconia types and the appropriate applications of those materials.

Effective communication with dental laboratory technicians is crucial when using dental zirconia for restorations. Understanding that not all zirconia is the same and discussing the specific types and their applications can significantly enhance the success of dental restorations. By selecting the appropriate type of zirconia based on the intended restorative need, dentists can maximize the material's benefits, ensuring optimal patient outcomes and improved clinical results.

Jeffrey Bonk, D.D.S., is a member of Spear Resident Faculty.

References:

Lawson, N. C., Frazier, K., Bedran-Russo, A. K., Khajotia, S., Park, J., & Urquhart, O. (2021). Zirconia restorations: An American Dental Association Clinical Evaluators panel survey. School of Dentistry Faculty Research and Publications, (457). Retrieved from https://adanews.ada.org/ada-news/2021/january/ace-panel-report-finds-dentists-favor-strength-of-zirconia-but-struggle-with-restoration-removal/

Sulaiman, T. A., Suliman, A. A., Abdulmajeed, A. A., & Zhang, Y. (2024). Zirconia restoration types, properties, tooth preparation design, and bonding: A narrative review. Journal of Esthetic and Restorative Dentistry, 36(1), 78-84. https://pubmed.ncbi.nlm.nih.gov/37840220/

Kongkiatkamon, S., Rokaya, D., Kengtanyakich, S., & Peampring, C. (2023). Current classification of zirconia in dentistry: An updated review. PeerJ. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10351515/