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With the availability of OTC whiteners comes an emerging issue: bleachorexia. This happens when whitening addicts load up on products and over-whiten, often not waiting enough time between treatments. They have a sort of dental dysmorphia that was reported recently on Good Morning America, and the results can be, well, quite dark.
The whitening agent, carbamide peroxide, can irritate gums so much that they start to bleed or recede. When you whiten too much, teeth are also susceptible to brittleness and sensitivity. Teeth can become so discolored they appear blue or translucent. In extreme cases, people must have their teeth capped or replaced because the enamel becomes too thin from over-whitening.
Dr. Vincent Mayher, a New Jersey dentist, said that toothpastes can clean off stains, but the term "whitening" is misleading because toothpastes only clean the tooth surface. Bleaches in toothpastes are useless because they get rinsed away before they do anything. If a toothpaste is too abrasive, it can wear away the outer layer of enamel on a tooth, exposing the yellowish dentin beneath, Mayher added. That means darker teeth instead of whiter teeth.
A recent study published in the Journal of Clinical Dentistry reported on research on abrasiveness and the cleaning power of 26 whitening toothpastes.
Anything that had a relative dentin abrasion (RDA) score of more than 100 was considered highly abrasive; if the RDA was above 150, the toothpaste was considered potentially damaging to enamel. The results showed that Crest White Vivid ranked 17th in terms of cleaning but was the fourth-most abrasive, scoring above 200. Rembrandt Intense Stain came in around 90, but was not the strongest in terms of cleaning power. Ultrabrite Advanced Whitening from Colgate earned top honors for stain removal, but that removal comes at a price, as the RDA was about 260.
Lead study author Bruce Schemehorn said it's a general rule that the most effective toothpastes are generally the most abrasive. When asked what the ideal product is, he responded, "I've been studying this for 30 years, and I haven't found it yet."
To whiten safely, consult with your dentist first to ask about your options; if you use an OTC tooth whitener, stick to the top brands. If you experience discoloration or sensitivity, stop product use. And, dentists warn, wait six months between treatments. "Bleaching is very effective in moderation and it's safe in moderation," says Dr. Jennifer Jablow, a dentist from New York.