Different Types of Zirconia Teeth on Your 'All On 4' Dental Implants

For many years, we have been helping a lot of people rebuild their smiles, and often we replace a full set of teeth with dental implants. One name for this treatment is All On 4.

Over this time, we have used many types of materials for the final teeth, and they all have their advantages and disadvantages.

These days, zirconia teeth seem to give us the least long-term issues. That said, there are many variations of zirconia, and I want to help patients who are considering this kind of treatment to understand the pros and cons of the different types available.

Before we get into this, let's talk about general bridge design. There are two variations, these are screw vs. cement-retained.

When you have the dental implants placed, you will have the "abutment" poking through the gum, and when all the teeth are removed, this is what you can see.

The teeth will then fix to these abutments, and there are two ways they can be fixed.

The most popular these days is the screw-retained prosthetics, where the final teeth are screwed down onto the dental implants. Here you can see the abutments are attached to the implants (the small parts between the implants and the teeth), and then the teeth are fixed to the abutments with screws.

The other way is to glue the bridge to the dental implants (or more accurately, to the abutments), which is known as 'cement-retained'. The abutments are different for this solution, but it's the concept we need to pay attention to.

Notice that there are no screw threads between the teeth and the abutment here. The teeth will be fitted with a specialist cement adhesive to the metal abutments.

The advantage of screw-retained is that the bridge can be removed easily, to inspect the dental implants.

The disadvantage is that the fit needs to be perfectly accurate (as there is no glue to fill up any discrepancies), which requires much more attention to detail, time, and therefore cost.

In general, we have only seen cement-retained bridges where the treatment has been carried out abroad. It is not a routine thing in the UK.

Even the lower-cost 'All On (x)' providers in the UK all seem to provide their patients with screw-retained bridges.

The other key disadvantage of cement-retained is excess cement. This has been shown to cause early implant failure, and this is a key reason that it is not used so much these days.

Different Types of Screw-Retained Bridges

Now that (hopefully) we can agree that the teeth should be screw-retained, let's look at the different types of zirconia bridges for your 'All On (x)' treatment.

There are three main variations, of which I have tried two over the years.

Option one (and probably the most common) is to have metal housings placed within the zirconia bridge.

This metal housing will fit on the implant, and the whole thing is screwed down.

In this scenario, most of the bridge is zirconia, and these metal housings are cemented into the zirconia.

This type of bridge is more cost-effective, because these metal housings are not custom-made to the patient, and manufacturing zirconia is actually not that expensive.

However, there is an issue that we have seen twice, with these types of bridges, and that is a full fracture.

Why Did This Happen?

Most of the research that you do online will lead you to think that zirconia is the strongest, and therefore the best material for teeth.

It does have high strength in compression, but if you try and twist the material, it is not so strong. This is typical of ceramic-type materials.

So, in our opinion, a better solution is to have a metal bar within the zirconia.

The metal bar connects all of the dental implants, and metal is stronger than zirconia, it performs better under twisting or flexing stress, the only downside is that it doesn't look like teeth.

Unless you are going for the Jaws, from James Bond look.

So for the aesthetics, we use zirconia, and we now have the best of both worlds.

The downside of this type of bridge is the cost. This metal bar is a completely custom to fit onto the dental implants - all the records need to be checked and double-checked, and there are only a few milling centres in the world that can produce these metal bars from a solid block of titanium to the level of accuracy that is needed in this application.

You might think that we can 3D print metal now - is that good enough? The answer is no, this process results in a weaker metal than what we need, and also it is not as accurate as we need.

So, as it is right now, milling a metal bar is the best solution for a full set of teeth on dental implants.

But what about the third option?

But there is a third option that I have not used before. This is a full zirconia bridge, without the metal inserts.

This is a similar solution to the first one (with the metal inserts), but in effect, the metal insert is milled from Zirconia.

An advantage here is that there are fewer parts, so less failure points.

With the metal inserts, over time, they can become unglued, so by not having them, this is no longer an issue.

However, we still have the material issues of zirconia, which is why I am not keen on this idea.

Also, it is the newest solution, so there is no long-term information on this solution. There are fewer components, so I assume it is less expensive, but that is the only advantage that I can think of.

These days, we primarily use the metal bar and zirconia option, as our patients would prefer to have the best quality materials. None of them would ever be able to tell the difference once it's fitted.

As you can tell, there are many ways that any business, not just dentistry, can reduce costs without the customer ever knowing, but if you are trying to deliver an excellent quality result, then it goes against our morals and ethics to use something that we know has failure points.

The quality of the technician matters a lot in delivering good quality dental care, and I will expand on this in future videos and blog posts, so if you would like to hear about this, subscribe to our newsletter, which I personally write for you, every few weeks.

Have a great day!

Gurs