Your wedding is coming up, and you want your smile to be its brightest. Or maybe you have an important speaking engagement. Whatever the reason, tooth bleaching isn't just for movie stars, and it isn't just for one day. Many people have had their teeth bleached, and probably millions more are thinking about it. The desire for a brighter smile with whiter teeth is very strong, and tooth bleaching safely lightens the color of the teeth, lasting for up to five years. The most effective and safest method of tooth bleaching is dentist-supervised.

Generally, bleaching is successful in at least 90 percent of patients, though it may not be an option for everyone. Consider tooth bleaching if your teeth are darkened from age, coffee, tea or smoking. Teeth darkened with the color of yellow, brown or orange respond better to bleaching. Gray stains caused by fluorosis, smoking or tetracycline use can be lightened, but results are not as dramatic. If you have very sensitive teeth, periodontal (gum) disease or teeth with worn enamel, your dentist may discourage bleaching.

First, the dentist will determine whether you are a candidate for tooth bleaching and what type of bleaching system would provide the best results. If you're in a hurry for whiter teeth, you may decide to have your teeth lightened immediately. Your dentist will use either an in-office bleaching system or laser bleaching while you sit in the dental chair. Some patients choose dentist-supervised at-home bleaching, which is more economical and provides similar results.

If you don't choose laser bleaching, at your next appointment your dentist or hygienist will make impressions of your teeth to create a mouthguard appliance. The mouthguard is custom-made for your mouth and is lightweight so that it can be worn comfortably while you are awake or sleeping. The mouthguard is so thin that you should even be able to talk and work while wearing it. Along with the mouthguard, you'll receive the bleaching materials. You'll be given instructions on how to wear the mouthguard.

Some bleaching systems recommend bleaching your teeth for several hours a day. Generally this type of system requires two to four weeks to complete. Other systems recommend bleaching at night while you sleep. This type of system usually requires only 10 to 14 days to complete.

Over-the-counter bleaching systems are also available and are generally safe and effective, although it is best to check with your dentist before using these products. These systems, which come in the form of strips and gels, usually contain a lower strength of bleaching agent than products used in the dentist's office. For this reason, they must be used longer to achieve a desired effect, but they are also cheaper.

Lightness should last from one to five years, depending on your personal habits such as smoking and drinking coffee and tea. At this point you may choose to get a touch-up. The retreatment time is much shorter than the original treatment time.

The active ingredient in most of whitening agents is carbamide peroxide; when water comes into contact with this white crystal, the release of hydrogen peroxide lightens the teeth.

Several studies have proven bleaching to be safe and effective. The American Dental Association has granted its seal of approval to some tooth bleaching products. Some patients may experience slight gum irritation or tooth sensitivity, which will resolve when the treatment ends.

No one can really predict how much lighter your teeth will become. Every case is different. Typically, there is a two-shade improvement as seen on a dentist's shade guide. The success rate depends upon the type of stain involved, the type of bleaching procedure and your compliance. Bleaching can only provide a shift in color from gray to a lighter shade of gray, for example. Bleaching does not lighten artificial materials such as bonding or veneers.