Teeth Whitening

Teeth whitening is one of the most popular cosmetic dentistry treatments offering a quick, non-invasive and affordable way to enhance a smile.  Universally valued by men and women alike, whitening (or bleaching) treatments are available to satisfy every budget, time frame and temperament. Whether in the form of professionally administered one-hour whitening sessions at a dental office or cosmetic spa, or home-use bleaching kits purchased at your local drugstore, solutions abound.

Virtually everyone who opts for a teeth whitening solution sees moderate to substantial improvement in the brightness and whiteness of their smile. That said, it’s not a permanent solution to discoloration and requires maintenance or “touch-ups” for a prolonged effect.

In this article we break down everything related to teeth whitening, including the process of tooth discoloration, what causes staining, the various treatment options available, and their associated risks and costs.

Bleaching vs. Whitening: What’s the Difference?

According to the FDA, the term “bleaching” is permitted to be used only when the teeth can be whitened beyond their natural color. This applies strictly to products that contain bleach — typically hydrogen peroxide or carbamide peroxide.

The term “whitening” on the other hand, refers to restoring a tooth’s surface color by removing dirt and debris. So technically speaking, any product that is used to clean the teeth (like a toothpaste) is considered a whitener. Of course, the term whitening sounds better than bleaching, so it is more frequently used — even when describing products that contain bleach.

The bleach preference for in-office whitening, where time is limited, is powerful and fast-acting hydrogen peroxide. When used in bleaching teeth, hydrogen peroxide concentrations range from approximately nine percent to 40 percent.

By contrast, the bleach of preference for at-home teeth whitening is slower-acting carbamide peroxide, which breaks down into hydrogen peroxide. Carbamide peroxide has about a third of the strength of hydrogen peroxide. This means that a 15 percent solution of carbamide peroxide is the rough equivalent of a five percent solution of hydrogen peroxide.

An Examination of Tooth Enamel

Most of us start out with sparkling white teeth, thanks to their porcelain-like enamel surface. Composed of microscopic crystalline rods, tooth enamel is designed to protect the teeth from the effects of chewing, gnashing, trauma and acid attacks caused by sugar. But over the years enamel is worn down, becoming more transparent and permitting the yellow color of dentin — the tooth’s core material — to show through.

During routine chewing, dentin remains intact while millions of micro-cracks occur in the enamel. It is these cracks, as well as the spaces between the crystalline enamel rods, that gradually fill up with stains and debris. As a result, the teeth eventually develop a dull, lackluster appearance.

Teeth whitening removes the stains and debris, leaving the enamel cracks open and exposed. Some of the cracks are quickly re-mineralized by saliva, while others are filled up again with organic debris.

Tooth Discoloration: Extrinsic vs. Intrinsic Staining

There are two categories of staining as it relates to the teeth: extrinsic and intrinsic.

Extrinsic stains are those that appear on the surface of the teeth as a result of exposure to dark-colored beverages, foods and tobacco, and routine wear and tear. Superficial extrinsic stains are minor and can be removed with brushing and prophylactic dental cleaning. Stubborn extrinsic stains can be removed with more involved efforts, like teeth whitening. Persistent extrinsic stains can penetrate into the dentin and become ingrained if they are not dealt with early.

Intrinsic stains are those that form on the interior of teeth. Intrinsic stains result from trauma, aging, exposure to minerals (like tetracycline) during tooth formation and/or excessive ingestion of fluoride. In the past, it was thought that intrinsic stains were too resistant to be corrected by bleaching. Today, cosmetic dentistry experts believe that even deep-set intrinsic stains can be removed with supervised take-home teeth whitening that is maintained over a matter of months or even a year. If all else fails, there are alternative cosmetic solutions to treat intrinsic staining, such as dental veneers.