Whitening and Bleaching

Understand the Difference

First, if you notice the terms “whitening” and “bleaching” seemingly being used interchangeably, it would be appropriate to explain the differences between these two.

Whitening generally refers to removal of stains that are embedded into the layer of proteins known as the pellicle, which naturally covers the surface of the tooth and provides the tooth’s first line of defense from acids that draw minerals from the enamel surface, making it softer. The stains come from foods and drinks containing dark colors, such as coffee, tea, red wine, tobacco, and others. Toothpastes with “whitening” on the label contain an abrasive ingredient that reduces enamel surface stains by mechanical removal of this pellicle. The downside is that this process can lead to abrasion of the enamel and can contribute to tooth sensitivity, especially if there are any exposed root surfaces. The acidity of many over the counter bleaching products like adhesive strips is strong enough to chemically break down this protective layer.

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Bleaching is a more aggressive technique, and involves changing the color of the dentin, which is the darker, thick layer of tooth under the relatively thin enamel surface. Hydrogen peroxide penetrates the porous enamel layer to reach deeper into the tooth and break down the darker colored molecules present there. Hydrogen peroxide is the active ingredient in bleaching gels and functions best in an alkaline pH environment for a deeper and longer lasting bleaching effect than surface lightening. It is the dentin layer that determines the overall dark or light appearance of our teeth, and it tends to darken as we age.

So toothpastes and mouthrinses that say “Whitening” on the label do not bleach teeth, they act by removing surface stains either mechanically or chemically, revealing your teeth at their true natural color, unsullied by any stains that have accumulated on the surface. If you find yourself paying closer attention to toothpaste ingredient labels, don’t be alarmed if you find the abrasive hydrated silica as an ingredient, even in formulas for sensitive teeth. This is because there are different grits of silica, from fine to coarse. The coarse variety is used in whitening pastes, the finest are in some sensitivity products. For additional information about toothpastes, go to the information tab and select “Toothpaste".