Metamerism – Why Tooth Color Changes Under Different Lighting

What is Metamerism

Definition and Everyday Example

Metamerism is a phenomenon where two objects appear to be the same color under one lighting condition, but differ under another. The material itself does not change – what changes is the way the eye perceives the light reflected by that material.

Example: You buy a shirt online – in the photo it looks black, but when it arrives, it turns out to be grey. The photo was taken in studio lighting, and you are looking at it in natural light. This is metamerism.

Why This Is a Problem in Prosthodontics

Lighting Conditions Change

Patients live in various environments: an office with fluorescent lighting, home by a window, a restaurant with halogen lights, a smartphone screen. Each of these sources changes the perception of the prosthetic restoration's color.

A patient comes for a check-up and says "the color has changed." The color hasn't changed – the lighting conditions are different. This is not a lab error – it's physics.

The Lab Works Under One Light

The colorist in the lab works under a standard 5500 K lamp (daylight standard). When the restoration goes to the practice under a different lamp or to the patient at home – the color looks slightly different. Minimizing this difference is part of the quality procedure.

Three Main Types of Light Sources

Natural Light (5500 K)

Sunlight ~5500 K is the standard for evaluating prosthetic colors. It shows the color "as it is" – objectively. deltalabs. practice: we always test restorations in natural light before shipping. If it looks good in natural light – it will look good in 90% of conditions.

Artificial Light: Halogen, LED, Fluorescence

Halogen (3200–3400 K) gives a warm, yellow light – colors appear more yellow-brown. LED (4000–6500 K) is neutral or cooler. Fluorescence (4000–5000 K) with a discontinuous spectrum sometimes gives a "grey" effect. If the practice works under halogen light – it's worth informing the lab. deltalabs. asks about lighting conditions in the practice for challenging color cases.

Screen Light (Smartphone, Computer)

LED with a blue dominant (~6500 K). Colors appear cooler. The patient sends a photo of the restoration on WhatsApp – it looks different on screen than in reality. This is a normal phenomenon, not an error.

How to Minimize Metamerism – Protocol

• Standardization of the working lamp – the lab works under 5500 K (daylight). Additional lamps: halogen 3200 K and a natural window for testing.
• Evaluation in natural light – the colorist evaluates the finished restoration by the window before shipping.
• Testing under various conditions – 5500 K + 3200 K + natural. If the color change is drastic – the design requires correction.
• Communication with the practice – we ask about the type of lamp in the practice. If the lamp is different from 5500 K – we adjust the coloring approach.

Color Shade Errors

Color evaluation under 100% power halogen light – the restoration looks too yellow. When it goes to the practice under normal lighting – it is much whiter than expected.

Assumption that digital wax-up = exact color – a wax-up on screen is a projection under a blue LED dominant. The color on screen ≠ the color of the physical restoration in natural light. There is always a metameric delta.

Lack of testing under various conditions – if the colorist checks the restoration only under the main lamp, surprises await the doctor and patient.

Frequently Asked Questions

Does metamerism indicate a lab error?

Not always. Metamerism is physics – any two light sources can change color perception. A lab error would be not checking the restoration under various conditions. Minimizing metamerism is part of the procedure.

What lighting is "best" for color evaluation?

Natural daylight 5500 K is the standard. These are the conditions in which the patient most often sees the restoration (window, outdoors).

Can I ask the lab to match my practice's overhead lamp?

Yes – and it is a reasonable request. The information "I work under a 3200 K halogen lamp" changes the colorist's approach.

What to do if the patient complains about color change in different rooms?

Explain metamerism – it's physics, not an error. Show the restoration by the window, under a desk lamp, and in the practice. If the change is subtle – everything is normal.

Challenging color case? Contact us – we will advise on how to test the restoration under the lighting conditions in which the patient will see it daily. Also, read the article on ceramic surface texture – smoothness affects light reflection and color perception.