People have been whitening their teeth since at least the time of the Pharos when ancient Egyptians used a mixture of pumice stone and vinegar as a teeth-whitening agent. Those Egyptians were on the right track concerning teeth whitening, as many of today’s toothpaste brands promote whiteness with abrasive additives similar to pumice. The ancient Romans also whitened their teeth, though we don’t believe modern dentistry has adopted the mixture of urine and goat’s milk they used as a whitening agent.

While your smile may only make up a small component of your overall physical look, it plays a leading role in your psychological health and well-being. Several studies have linked people’s self-confidence levels to the health and beauty of their smiles. Researchers have also determined that smiling helps release mood-boosting endorphins, relieves stress, and even lowers heart rates. In fact, one study determined that the health benefits of smiling are even produced when smiles are faked.

People tend to consider whiter and brighter teeth so crucial to the aesthetics of their smile that most toothpaste brands, mouthwashes, and many other products—such as gum—now come with whitening additives. While these products may help whiten teeth a bit, professional teeth whitening remains the only surefire way to whiten teeth. Many people balk at professional in-office teeth whitening treatment offered by dentists due to their high costs. Instead, they turn to over-the-counter teeth whitening kits.