Tooth Whitening

By Catherine M. Fascilla, D.D.S.

People have been trying to whiten their teeth for thousands of years. The Egyptians used a paste of vinegar and pumice that they brushed on their teeth with frayed twigs. It was believed that the whiter a person’s teeth were, the wealthier they were. Ancient Romans used urine to whiten teeth until they discovered that it was the ammonia in the urine that whitened the teeth. The practiced was eventually abandoned. Before dentists, barbers fixed problem teeth by extracting them. They whitened teeth by scraping them with metal files and applying nitric acid. This process was very uncomfortable and led to damaged enamel that was more susceptible to tooth decay.

Modern methods of whitening began in the 1980’s when dentists stumbled upon bleaching. They noticed that the hydrogen peroxide used to treat gum disease made teeth whiter. Peroxide was then incorporated into gels and is now available in many types of whitening systems, including whitening tooth-pastes, over-the-counter gels, rinses, strips, and trays and products used in the dental office. Hydrogen peroxide, carbamide peroxide or both are the active ingredient in almost all whitening products. It is not completely understood how whitening products work but it is believed that these agents diffuse through enamel and dentin. They seep into the “pores” of the enamel and dentin and clarify the organic material by breaking down molecules. Double- carbon bonds in organic matter that builds up in the tubules (“pores”) of your teeth over time absorb light and give teeth their yellowed appearance. It is believed that peroxide breaks these bonds creating single-carbon bonds that reflect light and make teeth appear brighter.

Whitening toothpastes work by removing superficial stains with mild abrasives and polishing agents. Whitening strips, gels and rinses use peroxide to whiten. The longer they stay in contact with the tooth surface, the more effective they are. Rinses have limited effectiveness because of the limited contact they have with teeth. Whitening rinses and toothpastes are best used as maintenance products.

Tray-based whitening systems, purchased over-the-counter or from your dentist involves filling a mouth guard-like tray with a gel containing a peroxide-bleaching agent and wearing the tray for a period of time ranging from fifteen minutes once or twice a day to overnight for up to four weeks or even longer (depending on the degree of staining and the desired level of whitening). The efficiency of the product is directly related to the percentage of peroxide used and the length of time applied to teeth.

Procedures used in the dental office include take home tray-based methods (using custom fitted trays) or in-office treatment with the application of a light over the gel to enhance the results. The methods provided by your dentist are usually the most effective but may also be the most expensive. Great results can also be achieved with over-the-counter methods (like whitening strips) that are generally less expensive but take more time.

Everyone can brighten their smile. Yellow stains are the easiest to treat. Dark brown, blue and grey stains are the most resistant. Crowns and fillings will not change color. Your dentist can help you choose the product or method that works best for you. With a little time and effort, you can have a brighter smile!

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