"I want them white." We hear it almost every week, and it's a fair thing to want. The trouble is that natural teeth aren't one colour, and the whitest white is rarely the one that looks best.
Why a tooth isn't simply white
A tooth has layers. Inside is dentine, which is naturally a warm yellowish colour. Over it sits enamel, which is partly see-through, a bit like frosted glass. What you see is the dentine glowing through the enamel.
That's why a healthy tooth changes colour from top to bottom. Near the gum, where the enamel is thin, it looks warmer. Towards the biting edge, where there's enamel but little dentine, it gets lighter and can even look faintly bluish or grey. If you hold your front teeth up to a window you might notice the edges let light through. That's normal, and it's a big part of why real teeth look real.
Three ways to describe a shade
When we talk about colour with a ceramist, we're really talking about three things at once.
Hue is the colour family. Most natural teeth sit somewhere between yellow and orange-brown, with a few leaning a little more red or grey.
Chroma is how strong that colour is. Two teeth can share a hue, but one looks pale and the other deep yellow.
Value is how bright or dark the tooth is. This is the one that matters most. Get the brightness wrong and a crown will stand out from across the room, even if the hue is spot on. Your eye notices lightness long before it notices colour.
Then there are the small things: tiny white flecks, a soft glow, slightly clearer edges. Leave them out and a crown can look flat, more like a bathroom tile than a tooth.
How we match a shade
You may have seen a shade guide, a fan of little sample teeth with labels like A1, A2 and B1. Roughly speaking, the letter is the colour family and the number tells you how deep it is, with lower numbers lighter. It's a useful starting point, but colour is slippery, so we're careful about how we use it.
We check shade at the start of the appointment, because teeth that have been propped open and drying for half an hour look whiter than they really are. We do it in good, neutral light rather than under a yellow lamp. And we photograph the shade tab right next to your teeth, so the technician making your crown or veneer sees exactly what we saw.
Picking the right white
The best shade suits your face: the whites of your eyes, your skin tone, your age. Very bright, very flat white can look great in a filtered selfie and strange across a dinner table.
One practical tip if you're planning crowns or veneers on front teeth and also want them brighter: whiten your natural teeth first. Porcelain doesn't whiten later, so we match the new work to your new shade, not the old one.
Next time, we'll look at why teeth stain in the first place, and why some stains polish off while others don't.