What do teeth look like under veneers? Before bonding, years later, and when a veneer comes off

Right after preparation: what the tooth looks like the day the veneer goes on

The photos people search for, teeth filed down to small tapered stumps, are not teeth prepared for veneers. They are teeth prepared for crowns, which need 60 to 70% of the tooth removed on every side so a cap can fit over the top. A veneer only touches the front.

A tooth prepared for a 0.3 mm veneer looks like the same tooth with a matte front. The dentist smooths a fraction of a millimetre off the surface you see when you smile, keeps the biting edge, keeps the back, and stays inside the enamel. On some teeth, usually small or slightly inward-set ones, nothing is removed at all and the veneer is bonded to untouched enamel. You could look at the prepared tooth in a mirror and, apart from the dull finish, not tell it had been touched.

The difference is not cosmetic. Enamel on the front of a tooth is roughly 1 to 2 mm thick, and the nerve sits well behind it in the pulp. A veneer preparation never gets near it, which is why it feels like pressure rather than pain and why it rarely leads to a root canal. A crown preparation goes through the enamel into dentin on all sides and sits much closer to the nerve. Everything that follows in this article depends on which of those two was done.

Under the veneer, years later

Porcelain is sealed and cannot decay, and the tooth under it is covered, so what you find when a veneer is lifted after ten years is usually enamel that looks the same as the day it was prepared. In pooled data on 6,500 veneers, 99.3% of teeth were free of decay at ten years, and only 16 of the 6,500 needed a root canal.

When something does go wrong, it is at the edge. The margin is the thin line where porcelain, cement, enamel and gum meet, and it is the only part of the tooth that is both exposed and hard to clean. Plaque left there inflames the gum and, over years, can start decay in the natural tooth just below the porcelain. In a bad case the veneer looks fine from the front while a brown line creeps along the gum. That is not the veneer failing. It is the same decay a tooth without a veneer would get in the same spot with the same brushing.

The other thing you can see under an old veneer is the preparation it was given. A veneer bonded to enamel comes off with the enamel intact. A veneer that was cut too deep, into dentin, often comes off with dentin that has darkened and softened, because the dentin bond is weaker and lets in moisture over time. A 15-year study of 672 veneers found survival of 96.7% on enamel and a failure risk about 3.5 times higher once more than 30% of the surface was dentin. The tooth under a shallow veneer ages well. The tooth under a deep one does not.

What the tooth looks like when a veneer comes off

The honest line is this: once enamel has been removed, the tooth will always need a veneer or another restoration, so veneers are replaced rather than simply taken off. The amount removed decides how good the tooth under them looks when that day comes. A 0.3 mm preparation keeps that day easy.

Do teeth rot or turn yellow under veneers?

Rot, rarely, and only at the margin for the reasons above. Yellow, no. The tooth under a veneer is not exposed to coffee, wine or air, so it does not darken the way an exposed tooth does. What people notice as 'yellow under the veneer' is usually one of two other things: a thin porcelain veneer showing the natural tooth color through it, which is a shade decision made at the mock-up, or a margin that has stained because the cement line was not kept clean.

Both are preventable, and both are decided before bonding. The shade is matched against your skin and the whites of your eyes in daylight, and if your natural teeth are darker than the shade you want, the ceramist uses a slightly more opaque porcelain so the tooth does not show through. The margin is placed where you can reach it with floss. From then on it is brushing, flossing at the gum line and a cleaning every six months, as laid out in how to take care of porcelain veneers.

How to make sure your teeth look good under their veneers in 2040

1. Ask how many millimetres come off each tooth, and where. A veneer answer is a fraction of a millimetre from the front. 'All around' is a crown.
2. Ask whether the preparation stays in enamel. If the answer is 'it depends', ask which teeth might go into dentin and why.
3. Look at your prepared teeth. Between Visit 2 and Visit 3 you can see and photograph them. Full-sized teeth with a matte front are right. Pegs are not.
4. Keep the margin clean. Soft brush, floss under the gum edge, no alcohol mouthwash, a cleaning every six months with a non-abrasive paste.
5. Wear the night guard if you grind. Grinding is what cracks porcelain and loads the margin.
6. Keep the X-rays. A bitewing every one to two years shows the tooth under the veneer while anything starting is still small.

When I lift a veneer that was bonded to enamel ten years ago, the tooth underneath looks like the day I prepared it. That is the whole argument for 0.3 millimetres.

If you want to know how much enamel your own teeth would need to give up, send three photos through the free photo evaluation. A doctor replies within 6 hours with a tooth-by-tooth answer and a written price. What the week itself looks like is on the Smile Design page.