Teeth Whitening: What Works and What It Won't Fix

Whitening is the cosmetic question I get asked most, and it usually arrives sideways. Someone mentions at the end of a cleaning that their teeth used to be whiter. It is a reasonable thing to want. It is also the treatment where expectations and results drift apart more than almost anything else we do, mostly because nobody ever explains what whitening actually acts on.

Why teeth darken in the first place

Two different things are going on, and they respond differently.

Extrinsic staining sits on the outside of the enamel. Coffee, tea, red wine, dark sodas, tobacco and some spices leave pigment on the surface, and it builds up over years. This is the kind of discoloration that responds best to whitening, and some of it comes off with a cleaning alone.

Intrinsic discoloration is in the tooth itself. Enamel thins with age, and the dentin underneath, which is naturally yellower, shows through more. An injury to a tooth, certain antibiotics taken in childhood, and too much fluoride while the teeth were still forming all change the color from the inside. Whitening helps with some intrinsic discoloration and does very little for other kinds.

So when someone asks whether whitening will work for them, the honest answer starts with working out which of these is in play.

How whitening actually works

Nearly every product that genuinely whitens teeth uses a peroxide, either hydrogen peroxide or carbamide peroxide, which breaks down into hydrogen peroxide. It passes into the enamel and breaks apart the pigmented molecules causing the stain. Higher concentrations and longer contact times do more.

That is the whole mechanism. What separates the options is concentration, how long the gel stays on the tooth, and how well it is kept off your gums.

The options, briefly

• In-office whitening. A high-concentration gel applied here, with your gums protected, usually over one or two visits. The fastest and most controlled option, and the most expensive.

• Custom take-home trays. We take impressions, make trays that fit your teeth, and you wear them with a lower-concentration gel for a set time over a couple of weeks. In my experience this is the best value for most people.

• Over-the-counter strips and gels. Lower concentration and a one-size fit. They do work, just more slowly and less evenly, particularly if your teeth are not well aligned.

• Whitening toothpastes. These are mild abrasives that lift some surface stain. Useful for maintenance, but they will not change the underlying color of your teeth.

Charcoal and other do-it-yourself approaches come up often. Abrasive scrubbing does remove surface stain, but it can also wear enamel, and enamel does not grow back. I would rather you skipped it.

What whitening will not fix

This is the part worth reading twice.

• Crowns, veneers, bonding and fillings do not whiten. If you have a white filling on a front tooth, lightening the natural teeth around it can make that filling stand out more than it did before.

• Deep intrinsic staining, such as the banding left by tetracycline, often improves only a little.

• A single tooth that is dark because the nerve inside it has died needs a different approach entirely.

• Whitening changes color. It does not change shape, alignment, chips or gaps.

Whitening is also not permanent. How long it holds depends a great deal on what you drink and whether you smoke, and most people want some kind of touch-up eventually.

Sensitivity, and keeping it manageable

Sensitivity during whitening is common and usually temporary. Gum irritation happens when gel sits against soft tissue, which is the main argument for trays that actually fit. If you are getting sharp sensitivity, the usual adjustments are shorter wear times, skipping days, or using a desensitizing toothpaste with potassium nitrate for a couple of weeks before you start. Pushing through pain is not the answer. Tell me instead, and we will change the plan.

Before you whiten anything

One thing I will insist on: have an exam first. Whitening gel on an untreated cavity or an exposed root surface is genuinely uncomfortable, and peroxide does nothing about decay hiding under a stain. It is also a short conversation to sort out whether your discoloration is the kind that responds, and that alone saves people money.

Have a cleaning done first, too. A fair number of people are happier than they expected after a cleaning alone, and everyone else gets a more even result whitening clean teeth.

If you are thinking about it, bring it up at your next visit and we will look at what is actually causing the color and what is realistic for your teeth.

This post is general information rather than a diagnosis. What is right for your teeth depends on an exam.

Hashimi Dental, 3701 Market St. Suite E, Riverside, CA 92501