How a zirconia crown is made, from scan to finished tooth

Most people never see their crowns being made. You have your teeth prepared, wait a few days, and then something that looks like a tooth comes back. In between, the material goes through a surprisingly dramatic change. It is cut while soft, shrinks by about a quarter in a furnace, and only then becomes the hard ceramic that will sit in your mouth for years. Knowing the steps helps you understand why a crown trip takes the time it does, and what can go right or wrong along the way.

Step 1: preparing and scanning the tooth

A crown needs room. The tooth is shaped under local anaesthetic to make space for the crown's thickness, leaving a clear edge (the margin) for the crown to meet. How much is removed depends on the material and the tooth, and it is one of the decisions that matters most for the tooth's long-term health. Our page on what happens to your teeth explains this part in more detail.

Then the tooth is recorded. At our clinic this is done with a digital intraoral scanner rather than impression trays. A small wand captures thousands of images and stitches them into a 3D model of the prepared tooth, its neighbours and the opposite jaw. A 2018 review in the Journal of Prosthodontics found digital impressions were as accurate as conventional ones for crowns and short bridges, and quicker to take. For complete arches, the same review still favoured conventional impressions, so this is not a claim that scanning beats everything.

A scan of how your teeth meet is taken too, so the design software knows where the crown will touch the opposite teeth.

Step 2: designing the crown on screen

The 3D model goes into design software. Here the shape of the crown is worked out: the outline of the margin, the thickness of every wall, the contact points with the teeth on either side, and the bite against the opposite jaw. The software proposes a tooth shape from a library, and the designer adjusts it to your mouth.

Two details here affect fit. One is how clearly the margin can be seen on the scan; a 2015 review on tooth preparation found good detectability of the margin mattered more for a well-fitting crown than the exact edge design. The other is the cement space, a tiny gap left inside the crown for cement. A 2020 systematic review of zirconia crown fit found that increasing the cement space improved adaptation, and that crowns from digital impressions fitted as well as or better than those from conventional impressions. If you want to know more about the edge itself, see crown margins explained.

Step 3: milling soft zirconia, deliberately oversized

Zirconia for crowns comes as discs or blocks in a pre-sintered state. At this stage it is porous, almost chalky, and much softer than the finished ceramic. A 2008 review by Denry and Kelly described the two ways of machining zirconia: soft machining of these pre-sintered blanks, and hard machining of fully sintered material. Soft machining is now the usual route because it is faster and kinder to both the milling tools and the material.

The catch is shrinkage. When the porous blank is later fired to full density, it shrinks. The 2020 fit review put this sintering shrinkage at roughly 20 to 30%, and a 2022 systematic review on sintering noted that soft-milled restorations are milled about 25% larger to compensate. The milling software applies an enlargement factor that matches the specific blank, so the crown that comes out of the mill looks oddly large and pale.

Fully sintered blocks can be milled to exact size with no shrinkage. But the 2008 review raised concerns that hard machining can introduce surface damage and changes in the crystal structure, so it is used less for crowns.

Step 4: colour before the furnace

Colour can be built in at this stage in two main ways. Pre-shaded or multilayer blanks already contain pigment, often graded from a darker neck to a lighter biting edge. A 2019 study of one multilayer system found its layers differed only in their pigments, which is what produces that natural-looking gradient. Alternatively, a white blank can be painted or dipped in colouring liquids while it is still porous, so the colour soaks in.

The pigments are not entirely passive. A 2025 systematic review found that the metal oxides used to colour zirconia can alter grain size and porosity and affect translucency, hardness, toughness and strength, while showing no harmful effect on gum cells in the lab. Colouring is part of the material's chemistry, not a coat of paint, which is why makers specify how it should be done.

Step 5: sintering, where the crown becomes zirconia proper

The milled crown goes into a high-temperature furnace. Manufacturer data quoted in the 2019 multilayer study gave sintering conditions of 1,500 to 1,550 °C for two hours at the top temperature, and a full conventional cycle including heating and cooling can run for several hours. During this time the particles fuse, the pores close up, the crown shrinks to its designed size, and it gains its full strength and translucency.

Faster sintering programmes exist. A 2022 systematic review of conventional, speed and high-speed sintering found that fit and mechanical results were similar or better with the faster methods across 3Y, 4Y and 5Y zirconia, but that translucency was usually reduced when 3Y zirconia was speed-sintered. All the studies in that review were laboratory studies.

Step 6: staining, polishing and glazing

After sintering, the crown is checked on the model and the surface is finished. There are three tools here:

• Stains: fine coloured ceramic painted onto the surface to add detail, such as a slightly warmer neck or subtle edge effects.
• Glaze: a thin glassy layer fired on top to seal stains and give gloss.
• Polishing: mechanical smoothing of the zirconia itself with progressively finer polishers.

The finish matters for more than looks. A 2013 laboratory study in the Journal of Prosthetic Dentistry found polished zirconia caused the least wear on opposing enamel, while glazed zirconia caused significantly more, both to the enamel and to itself as the glaze wore away. That is why many crowns are polished where they bite and glazed or stained where they show. Our article on crown wear on opposing teeth covers this research.

Step 7: try-in, then fixing

Before anything is cemented, the crown is tried on the tooth. At our clinic fit, bite and shade are checked at this try-in before permanent fixing. If the bite needs a touch of adjustment, the adjusted area should be re-polished, because grinding leaves zirconia rough. If the edge does not seat properly, the right answer is a remake, not more cement. Once you and the dentist are happy, the crown is fixed. How that is done, and why zirconia is often cemented differently from E-max, is covered in how crowns are cemented.

This sequence is why a zirconia crown trip with us is a single visit of around 5 hotel nights, as described on the crown trip page. If you would like to know how your own teeth would be planned, ask for a free written plan through our contact page.

Common questions

Why is zirconia milled before it is fully hardened?

Fully sintered zirconia is extremely hard, which makes milling slow and wears out tools. Milling it in its softer pre-sintered state is quicker and gentler on the material. The trade-off is that it shrinks during sintering, which the software allows for by milling the crown oversized.

Are digital scans as accurate as impression trays for crowns?

A 2018 review found digital impressions were as accurate as conventional ones for single crowns and short bridges, and that digital scanning was faster. Conventional impressions still did better for full-arch work in that review.

Is a glazed or polished zirconia crown better?

Polishing gives the smoothest surface and laboratory studies suggest it is the kindest to the teeth it bites against. Glaze adds gloss and can carry surface stain for a more lifelike look. Many crowns are polished on the biting surfaces and glazed or stained where looks matter more.

How long does it take to make a zirconia crown?

Sintering alone often takes several hours, and staining or glazing adds more firing time. With us, a zirconia crown trip is one visit of around 5 hotel nights, including a try-in to check fit, bite and shade before the crowns are fixed.

What happens if the crown does not fit at the try-in?

Small adjustments to the bite or contacts can be made and the surfaces re-polished. If the fit at the edge of the crown is not right, the crown should be remade rather than forced on. That is the reason the try-in exists.

Sources

1. Ahlholm P, Sipilä K, Vallittu P, Jakonen M, Kotiranta U (2018). Digital versus conventional impressions in fixed prosthodontics: a review. J Prosthodont
2. Denry I, Kelly JR (2008). State of the art of zirconia for dental applications. Dent Mater
3. Podhorsky A, Rehmann P, Wöstmann B (2015). Tooth preparation for full-coverage restorations: a literature review. Clin Oral Investig
4. Ahmed WM, Shariati B, Gazzaz AZ, Sayed ME, Carvalho RM (2020). Fit of tooth-supported zirconia single crowns: a systematic review of the literature. Clin Exp Dent Res
5. Al-Haj Husain N, Özcan M, Dydyk N, Joda T (2022). Conventional, speed sintering and high-speed sintering of zirconia: a systematic review of the current status of applications in dentistry. J Clin Med
6. Gali S, Patel Z, Akanksha YN, Karuveetil V (2025). Effect of coloring pigments on the properties of dental zirconia: a systematic review and meta-analysis. J Esthet Restor Dent
7. Janyavula S, Lawson N, Cakir D et al. (2013). The wear of polished and glazed zirconia against enamel. J Prosthet Dent
8. Kolakarnprasert N, Kaizer MR, Kim DK, Zhang Y (2019). New multi-layered zirconias: composition, microstructure and translucency. Dent Mater

Checked October 2026. Where we give our own view as a clinic, we say so.