Although home tooth whitening kits continue to increase in popularity, few people really understand the exact process involved, how the teeth are actually lightened, and what to expect from the results.

Tooth whiteners are intended to remove stains from the surface of the teeth causing them to temporarily appear whiter and brighter using varying concentrations of either hydrogen peroxide or one of its derivatives, the more diffused form, carbamide peroxide, as its bleaching agent. The concentrations of the bleaching agents used in home teeth whitening kits that you will typically see are anywhere from 10 to 22% of carbamide peroxide.

Home teeth whitening kits containing just hydrogen peroxide are generally used for short periods of time, while those with carbamide peroxide are often intended to be used for as long as overnight depending on the amount of whitening desired and how badly the teeth are discoloured or stained.

Tooth discolouration may occur due to a number of causes, either external or internal, and when the whitening gel comes in contact with the teeth, oxidation occurs causing the stains to break down. During oxidation, oxygen molecules form creating free radicals that work to break down the compounds trapped within the microscopic pores of the tooth's surface causing them to appear darker.

When using a bleaching or whitening agent, you should expect to see about fifty percent of the final results within the first few hours of using the product.

Stains on the teeth caused externally are the result of drinking certain juices and soft drinks, coffee, tea, and smoking or using tobacco products. Internal reasons for discoloured teeth include the natural aging process, some type of trauma to the teeth, being exposed to either too much fluoride or the antibiotic tetracycline when the teeth were forming.

Internal staining of the teeth will require professional whitening procedures while over the counter home teeth whitening kits can be used successfully for removing external stains. Visiting a dentist before using a whitening kit is always wise as they can offer recommendations as to the concentration of whitener needed and what to expect in terms of results. Remember that dental fixtures such as partial dentures, fillings, or bonded teeth will not be affected by any tooth whitener.

Some people with sensitive teeth and gums may experience heightened sensitivity to sensations like hot and cold after using a tooth whitener, especially those without a lot of enamel protecting the teeth. In fact, the more enamel still on the surface of the teeth, the better they will respond to the whitening agent.

Enamel can be worn away by brushing too hard, using abrasive toothpastes, and eating acidic foods. If you have whitened your teeth and notice they seem whiter on the sides of the teeth and on the biting edges, the reason for this is more enamel here than on the front surface of the tooth.

Fortunately, the increased sensitivity experienced after whitening the teeth is a temporary occurrence and using a toothpaste intended for sensitive teeth can help.