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709: The Why’s and Y’s of Zirconia – Dr. Shashikant Singhal

How much do you know about zirconia? If zirconia is still a mystery, don't miss this episode! Kirk Behrendt brings in Dr. Shashikant Singhal, Director of Education & Professional Services at Ivoclar, to explain the different types of zirconia, its properties, and what dentists get wrong when using this material. To improve how you craft your dental masterpiece, listen to Episode 709 of The Best Practices Show!

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Main Takeaways:

  • Not all zirconia is the same.
  • Learn the properties of 3Y, 4Y, and 5Y.
  • Know the appropriate uses for each zirconia type.
  • Zirconia is strong — but each type has its limitations.

Quotes:

“Dentistry is changing fast, as we all know. Clinicians are trying to have something in their hands which is strong, reliable, and good looking also. But at the same time, there are so many different options out there in the market and it makes it difficult for them to make the right decision. We talk about ceramic materials as one of the options for indirect restorative products, and things have evolved. Things have evolved over a period of time. We started with feldspathic ceramic material, and we moved to lithium disilicate. Now, everyone talks about zirconia. And as you mentioned, do we understand these products in a proper way? What are their properties? Why is it important to understand these properties? Because it defines the clinical protocol.” (3:00—3:57)

“There are different types of zirconia, and it makes it really difficult for clinicians to understand which zirconia can be used where. Are these zirconias the same? The answer is, no, they are not the same. They are different types of zirconia. If I broadly classify it, there are three types of zirconia. One is 3Y, one is 4Y, and one is 5Y. The Y stands for the mole percentage of the yttria that we add into the zirconia powder.” (4:43—5:22)

“We have 3Y, 4Y, and 5Y. 3Y is the strongest, but more on the opaque side. 4Y is in between 3Y and 5Y. The translucency is in between as well, both strength and translucency. 5Y is your most translucent within the zirconia category, but weakest as well. You asked about the color. Color, in my mind, is a combination of chroma value and translucency coming into play as well. It's a combination of these three different parameters. So, again, all zirconias are not the same. You are trying to match the color with the natural dentition, but then the translucency comes into play as well. And when you're trying to match zirconia with the natural tooth structure, you need some translucency also. That's where the GT technology comes into play because that allows lab technicians to adjust the restoration within the part to get that translucency, and at the same time we have optimized the shade of our product closest to the VITA shade guide as well.” (10:09—11:38)

“Zirconia is a mystery for many clinicians . . . So, as I classify the different types of zirconia, I mentioned the strength of these as well. 3Y is the strongest, 5Y is the weakest, and then the difference in translucency. So, whenever I talk with dental experts — I will use the word dental experts here, including the clinician and the lab technicians — I ask the question, ‘Do you consider your treatment planning based on the zirconia you select?’ And I don't get a very confident answer because they think like, ‘Zirconia is zirconia.’” (12:16—13:03)

“If you are defining your treatment planning considering which end product you will use — that is your 3Y, 4Y, and 5Y — you will have a prep that is the tooth prep according to that product. So, if 3Y is the strongest, you can be most conservative in your tooth preparation for 3Y. Whereas for your 5Y, you have to be a little bit more aggressive. So, I will throw some of the numbers out there. Minimal reduction for your 3Y is around 0.5 millimeters to 0.6 millimeters, whereas your 5Y can range from 1 millimeter to 1.5 millimeters, depending on your cementation protocol. So, again, we are saying about the efficiency, if you understand the different Y’s of zirconia, you will do the prep in that way. You will prescribe the right zirconia based on the patient's demand and the clinical situation. Once you're communicating it properly with the lab, you will get the right restoration, and your efficiency and your chairside time will increase.” (13:11—14:26)

“For the dentist, beauty is important. I will say, on that — I'm saying 10 [out of 10 for importance] — it depends on the patient's expectation as well. Personally, I would like to deliver a gorgeous looking restoration. That will be my wish, that it should match the tooth structure most accurately. In the posteriors, I will say esthetics will be around a five or six. I'm not that worried. But on the anterior, I really want to match the shade and I really want to have good esthetics. So, for the anterior, I will score a 10. For the posterior, five is good enough.” (18:01—18:35)

“For posterior, [I rate strength as a] 10 [for importance]. Now, I will switch it. For posterior, a 10.  For anterior, I will say six. The reason is because of the masticatory forces that we are applying. When we bite, the posterior, on the back end, we are applying too much force. Whereas on the anterior, I'm not applying the same amount of force. So, the strength is important, always, but not to the highest degree.” (18:46—19:15)

“3Y is strongest, and 5Y is weakest within the zirconia category. So, what does it really mean? 3Y has a flexural strength of 1,100, whereas 5Y is 650 . . . The lower the number, the weaker the product is. So, you have 650 versus 1,100. So, 5Y is more indicated for anteriors — or many clinicians are using 5Y in the anterior because of the higher translucency — whereas your 3Y is used in the posterior. Why? Because of the same rating, as I said. I need a stronger product in the back of my mouth. In the front, I can use 5Y. But that being said, personally, I still prefer to use lithium disilicate in the anterior versus zirconia because I know the esthetics makes a huge difference for me. I said 10 for esthetics in the anterior, and I know lithium disilicate will be the best option for the anterior. That is my eMax lithium disilicate. So, I would prefer that for my anterior, and it might be the zirconia for the posterior.” (19:25—20:50)

“Sorry to say, I will say [people get] everything [wrong about zirconia]. The most important thing here is everyone thinks zirconia is the strongest. No doubt about it, zirconia is strong. But please understand, 3Y is strong, but not 5Y. So, 3Y, yes, it's the strongest product and you can put it anywhere in the patient's mouth. But the limitation is it is not as good looking. Whereas your 5Y, it is not strong. So, zirconia is not one solution for all clinical indications, and [dentists] need to understand that there are limitations to zirconia as well. So, one thing I will say that people think about zirconia is that zirconia is the strongest, it will not fracture, and all that. And that's not right, unfortunately. I've seen zirconia restorations fracturing as well, and I have seen good clinical data on that side, that your 5Y zirconias are fracturing.” (21:00—22:09)

“If someone has to take a final message from this particular session, I will say please understand which zirconia you are using. Not all zirconias are the same. You have 3Y, 4Y, and 5Y. 5Y is the weakest, and 3Y is the strongest. But that being said, all zirconias are not the same.” (24:01—24:27)

“Understand the product, prescribe the product, and do the treatment planning accordingly. That will be the key to success on the clinical side, and that would be really helpful.” (24:52—25:04)

Snippets:

0:00 Introduction.

1:57 Dr. Singhal’s background.

2:48 The background of zirconia.

4:27 The three types of zirconia and GT technology.

9:31 Color, explained.

11:58 Strength and reliability, explained.

14:30 Accuracy, explained.

17:31 The importance of beauty.

18:38 The importance of strength.

20:53 What people get wrong about zirconia.

22:12 The future of zirconia.

23:55 Final thoughts.

25:17 Learn more about Ivoclar and get in touch with Dr. Singhal.

Dr. Shashikant Singhal Bio:

Dr. Shashikant Singhal, BDS, MS, has diverse work experience spanning over a decade, and has held various positions in different organizations. He started his career as an intern at the College of Dental Sciences in 2008. In 2009, he worked as a graduate assistant at the UAB School of Dentistry, and also served as a supervisor at the UAB School of Public Health. In 2012, he joined the University at Buffalo's School of Dental Medicine as a materials research dentist. From 2012 onwards, he has been associated with Ivoclar NA, where he has held multiple roles including clinical specialist, manager of professional services, and director of professional services. He currently serves as the director of education and professional services.

Dr. Singhal also has a diverse educational history. He received his Bachelor’s in Dental Surgery (BDS) from Rajiv Gandhi University of Health Sciences from 2003 to 2008. He further pursued his education and completed a Master of Science (MS) degree in the Advance Clinical Dentistry Program at the University of Alabama at Birmingham from 2009 to 2011. Currently, he is enrolled in the Executive MBA program at the University of Rochester - Simon Business School, which he is expected to complete between 2022 and 2024.
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