Teeth on implants: acrylic, zirconia or porcelain?

First, let us separate two terms, because they get mixed up in everyday speech. The implant is the screw inside the bone; the tooth or bridge fitted on top of it is called the bridgework. So the question 'implant or zirconia?' compares two different layers: zirconia is a material for teeth and can be fitted on top of an implant or on top of your own tooth. The subject of this page is only the top layer, that is, what the tooth that goes on the implant is made of.

In full-mouth bridges, acrylic teeth are set on a metal or titanium bar; this is also commonly called a hybrid denture. It is light, absorbs impact to some extent and, when a tooth breaks, it can often be repaired without replacing the whole bridge. In return, it is softer than ceramic: over the years it wears, picks up stains, and the teeth may need renewing. A systematic review comparing it with porcelain-fused-to-metal bridges found that, alongside wear and fractures of the veneering material, inflammation around the implants (peri-implantitis) was also reported more often with acrylic bridges, while there was no significant difference in the loss of implants or bridges.

Porcelain fused to metal is made by building up porcelain on a metal framework, and it is the route that has been used longest for bridges on implants. A systematic review of multi-unit implant bridges still describes this material as the reference option. Its most common problem is the porcelain fracturing or chipping at the edges; in full-mouth bridges, this problem is reported to build up over the years and may need maintenance. If the gum is thin, the metal framework can show through as a grey shadow.

Zirconia is used in two different ways, and the difference between them matters. In the first, porcelain is built up on top of a zirconia framework; here too the weak point is the porcelain layer, and reviews show that chipping is a significant problem with these bridges. In the second, the tooth is milled from a single solid block, that is, monolithic zirconia, and there is no separate layer left on top to chip. For single crowns, monolithic crowns are reported to chip significantly less than layered crowns. In full-mouth bridges the short-term results are positive, but long-term data is still limited.

The hardness of monolithic zirconia is both an advantage and something to watch. It resists fracture, but it does not flex or absorb impact; the load is passed directly to the implants and the opposite jaw. That is why, if you have your own teeth in the opposite jaw, it matters that the surface is well polished and the bite is finely adjusted. In terms of appearance, monolithic zirconia may not let light through as well as layered ceramic; this difference comes up especially with front teeth.

Glass ceramic, especially lithium disilicate, is a material that lets light through very much like a natural tooth, and it is used mostly for single crowns at the front of the mouth. A large meta-analysis of single-tooth implant crowns found no significant difference in short-term survival between glass-ceramic, zirconia and layered ceramic crowns; for resin-based ceramic crowns, however, survival was markedly lower. Glass ceramic is not a preferred material for long bridges or for a full mouth.

The difference between a single tooth and a full-mouth bridge is what changes the choice of material most. For a single crown, the difference between materials is small, and the choice is often made on appearance and how well it matches the neighbouring teeth. In a full-mouth bridge, however, all the teeth in one jaw are carried in one piece, screwed to the implants; weight, repairability, whether it can be removed and refitted, and the load placed on the opposite jaw all come into the calculation. So there is no contradiction in recommending zirconia to the same patient for a single tooth and a different material for a full mouth.

Finally, a distinction to do with timing. In classic immediate loading protocols, for example many All-on-4 and All-on-6 plans, the first bridge fitted is a temporary bridge made of acrylic or a similar resin, and the permanent bridge is made separately months later. The Implant72 protocol has no such interim stage: on days 1 and 2, the shape and bite are settled with try-in teeth, and the teeth fixed to the implants on day 3 are the final teeth. The material comparison on this page applies directly to those final teeth.

The first list describes the situations in which a material's advantage becomes clear, the second the combinations that call for caution. The decision is made by looking at the examination, the bite and the length of the bridge together.

The material is not picked off a shade guide. The sequence below shows which questions the decision comes from.

1. 1

   How many teeth will be carried

   A single crown, a short bridge and a full-mouth bridge carry different loads. The longer the bridge, the more the weight, flexibility and repairability of the material matter.

2. 2

   What is in the opposite jaw

   Whether the opposite jaw has natural teeth, a fixed bridge or a removable denture changes the biting force. How the chosen material will interact with the opposing teeth also follows from this.

3. 3

   Teeth grinding and habits

   Habits such as grinding at night, crunching ice or opening things with your teeth are discussed. If you have any of these, avoiding layered surfaces and wearing a night guard come into it.

4. 4

   Smile line and expectations for appearance

   Whether the gum shows when you smile, and the length and shade of the teeth, are assessed. In full-mouth bridges, artificial gum can also be part of the design.

5. 5

   Trying it out at the try-ins

   In the Implant72 protocol, shape, length, speech and shade are tried out with the try-in teeth on days 1 and 2; the design of the final teeth fitted on day 3 is settled from these observations. In classic protocols, the same trial is done with a temporary bridge worn for months.

6. 6

   Putting the choice in writing

   The material of the final tooth, its framework, whether it is screw-retained or cemented, and how it will be repaired if it fractures should be shared with you in writing.

None of the materials below is right for every mouth. What makes each one strong can turn into a weakness in a different situation.

We write these not to run down any of the materials but so that you can ask the right questions when you read quotes.

The period after the final tooth or bridge is fitted needs regular check-ups, whatever the material. Below we set out how the material affects care.

1. Fitting day

   The bite is adjusted; if the surface has been adjusted, it is polished again. A surface left rough both strains the opposing tooth and holds plaque.

2. The first weeks

   You get used to speaking and chewing. If a point in the bite touches too early, it is corrected with an adjustment during this period; left as it is, it increases the risk of fracture.

3. At every check-up

   The tightness of the screws is checked, and the surface is checked for wear, chipping or cracks. With acrylic teeth, wear and discolouration are watched particularly closely, and with porcelain, chipping at the edges.

4. Over the years

   Acrylic teeth may need renewing; small chips in ceramic surfaces are managed by polishing or repair. Renewing the tooth on top while the implant stays in place is a normal part of the process.

There are no figures on this page, but the effect of the material on the scope of treatment is concrete. These are the items that set the scope:

Framework and material

Acrylic on a bar, porcelain fused to metal and monolithic zirconia involve different production steps and laboratory work.

Length and number of bridges

The difference between a single crown and a full-mouth bridge is large. If both jaws are treated together, two separate bridges are made.

Whether there is an interim stage

In classic immediate loading plans, a temporary bridge is fitted first and the permanent bridge is made separately months later. In the Implant72 protocol, the final teeth fitted on day 3 are the only bridgework. If you are comparing different quotes, ask in writing how many separate bridges are included.

Repair and renewal

Renewing acrylic teeth over the years and repairing any chips in ceramic affect the scope in the long run. How these will be handled should be discussed from the start.