Tooth whitening can be a very effective way of lightening the natural colour of your teeth without removing any of the tooth surface. It cannot make a complete colour change, but it may lighten the existing shade.
Professional bleaching is the most usual method of tooth whitening. Your dentist will be able to tell you if you are suitable for the treatment, and will supervise it if you are.
First the dentist will put a rubber shield or a gel on your gums to protect them. They will then apply the whitening product to your teeth, using a specially made tray which fits into your mouth like a gum-shield.
The total treatment can usually be done within three to four weeks. First, you will need two or three visits to the dentist. Your dentist will need to make a mouth guard and will take impressions for this at the first appointment.
Once your dentist has started the treatment, you will need to continue the treatment at home. This means regularly applying the whitening product over two to four weeks, for 30 minutes to one hour at a time.
However, there are now some new products which can be applied for up to eight hours at a time. This means you can get a satisfactory result in as little as one week.

Dental cleanings involve removing plaque (soft, sticky, bacteria infested film) and tartar (calculus) deposits that have built up on the teeth over time. Your teeth are bathed in saliva which contains calcium and other substances which help strengthen and protect the teeth.
While this is a good thing, it also means that we tend to get a build-up of calcium deposits on the teeth. This chalky substance will eventually build up over time, like lime scale in a pipe or kettle.
Usually it is tooth colored and can easily be mistaken as part of the teeth, but it also can vary from brown to black in color. If the scale, or calculus (tartar) is allowed to accumulate on the teeth it will unfortunately provide the right conditions for bacteria to thrive next to the gums.
The purpose of the cleaning and polishing is basically to leave the surfaces of the teeth clean and smooth so that bacteria are unable to stick to them and you have a better chance of keeping the teeth clean during your regular home care.
Also it leaves your teeth feeling lovely and smooth and clean. The professional cleaning of teeth is sometimes referred to as prophylaxis (orprophy for short). It's a Greek word which means "to prevent beforehand" - in this case, it helps prevent gum disease.