Tooth Shade: How the Colour of a Crown or Veneer Is Chosen

What shade guides and codes are

A shade guide is a set of tooth-coloured tabs. Two widely used systems come from the same maker: the classical guide has 16 tabs, and the 3D-Master guide has 26 tabs and chooses the shade in three steps¹ instead of one. A code such as A1 or 1M1 only means something together with the guide it comes from.

In a laboratory study, 60 dentists, technicians and students matched 40 ceramic samples. Shades chosen with the 3D-Master guide were on average slightly closer to the target than those chosen with the classical guide², a statistically significant difference. It was a laboratory study, and it does not show that one guide gives better results in patients.

No guide covers every natural tooth colour: a review of shade-matching studies notes that the available shade guides do not represent the true colours of teeth³. So a code is a starting point for the laboratory, not a promise of an exact colour.

Is a light shade "too white"?

There is no shade that suits everyone. Whether a light tab looks natural depends on the teeth that will sit next to the restoration, on whether all the visible teeth are being changed, and on the light you are seen in. Ask to see the tab held next to your own teeth before you agree. On a dark tooth, a thin veneer may not hide the colour underneath, even in a light shade.

Eye, camera or device: how reliable is each?

Choosing a shade by eye is subjective. A systematic review found that the visual method has lower accuracy and repeatability¹ and advises clinicians not to rely on their senses alone.

Two meta-analyses compared methods. One found that shades taken with instruments, such as spectrophotometers and cameras, were on average closer to the target than shades chosen by eye³. The other found that digital photographs reduced the colour difference, but that a spectrophotometer had no advantage over shade guide tabs⁴. Both were based on few, mostly small studies.

Intraoral scanners are a different case. In a meta-analysis, scanners picked the same tab as a spectrophotometer in about 38 in 100 readings with the 3D-Master guide and about 28 in 100 with the classical guide⁵, and the authors do not recommend using them to determine shade, although the certainty of this evidence was very low. A scanner is still useful for the impression itself.

In practice, a careful visual match combined with photos of the chosen tab next to your teeth can help document the shade choice for the laboratory.

Why the light and the person matter

The same tooth looks different under different light, which is also why teeth can look a different shade in photographs. In a laboratory study, dentists with normal colour vision matched shades significantly better under a standard daylight lamp than under a tungsten bulb⁶, while those with red-green colour deficiency did better under the tungsten light. In a randomised laboratory study with dental students, handheld shade-matching lights gave better scores than a viewing booth, and training also improved the scores⁷.

The matcher's sex does not appear to be critical. Of 37 studies on whether men or women match colours better, 25 found no significant difference⁸, and the authors concluded that sex is unlikely to be a critical factor.

Small differences can show. In a study of 175 observers looking at ceramic samples in a viewing booth, half noticed a difference of 0.8 units on the CIEDE2000 colour-difference scale, and half found a difference of 1.8 units unacceptable⁹. These are laboratory thresholds; they varied between groups of observers and between centres, and they cannot be compared directly with figures measured on other scales or under other conditions.

What whitening does not change

Whitening works on natural teeth. According to the American Dental Association, whitening will not work on caps, veneers, crowns or fillings¹⁰. After whitening, an existing restoration can therefore look darker than the teeth next to it.

That does not mean restorations are untouched. Laboratory studies show that bleaching may affect the surface, the edges and the colour of some restorative materials¹¹; the same 2004 review found no clinical reports of restorations needing to be replaced because of bleaching. A later review advises dentists to tell patients that restorations may need polishing or replacing at the end of whitening¹², and to avoid bleaching ceramic restorations, especially on front teeth, because their surface may become rougher.

If you are planning new crowns or veneers and also want lighter teeth, discuss both together before the shade is chosen. For whitening itself, see yellow stains on teeth and hydrogen peroxide for whitening.

At your shade appointment

• Ask to see the chosen tab held next to your own teeth, and say whether it looks right to you.
• Ask whether the shade will be recorded with photos of the tab beside your teeth for the laboratory.
• For front teeth, ask to see the crown or veneer tried in your mouth, and discuss how it looks, before it is permanently bonded or cemented.
• If only one or two teeth are being restored, the aim is usually to match the teeth next to them, not a code from a chart.

When to see a dentist

Colour is usually a question for a routine appointment, but see a dentist if:

• A single tooth darkens, especially after a knock
• A crown or veneer has a dark line or a chip at its edge, or the gum around it bleeds or recedes
• Teeth are very sensitive or painful during or after whitening

Emergencies. Facial swelling, a fever or throbbing pain needs a dentist without waiting. Difficulty breathing or swallowing: go to an emergency department or call 112.

Frequently asked questions