Carbamide peroxide

Carbamide peroxide, also called urea peroxide, is an oxidising agent, consisting of hydrogen peroxide compounded with urea. The molecular formula is CH₆N₂O₃, or CH₄N₂O.H₂O₂. It is a white crystalline solid that releases oxygen in contact with water.

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Uses

This chemical is commonly encountered in cosmetic dentistry, where it is used to "bleach" teeth. The active ingredient is hydrogen peroxide, which acts to oxidise interprismatic extrinsic staining within tooth enamel. There are several methods of applying the peroxide gel to the tooth ranging from night-guard application at home or in-surgery application. The bleaching obtained is proportional to the length of time the peroxide is applied to the tooth, and the concentration used. The concentration most commonly used for tooth whitening purposes is 22%.

Another application for this chemical is in hair dyes where oxidizing agents are required.

The chemical is a skin, eye and respiratory irritant. It is also corrosive and causes burns. It doesn't hurt at 10% concentration (3% hydrogen peroxide equivalent) but it might hurt at 35% (12% equivalent), causing white chemical burns on skin and gums alike.

Pure carbamide peroxide has the form of white crystals or crystal powder, is soluble in water, and contains approximately 35% hydrogen peroxide.

A 6.5% concentration solution is used to loosen and remove earwax. A 10% solution in glycerol is used to treat ulcers and other lesions in the mouth, and is sold under the trade-name Gly-Oxide.