There are many brands of teeth whitening systems are available in market like Opalescence, BriteSmile  and"Zoom" which  is the best teeth whitening system (as seen on ExtremeMakeover TV show.It gives immediate results and the teeth become six to ten shades whiter within 1hour!
Zoom whitening procedure:
First of all clinician cleanses the teeth by removing the tarter and surface stains by scaling and polishing. Now the photographs of the teeth are taken to record the natural shades of teeth. These photographs are shown to patient to show the difference achieved in shades after the procedure. Gums and lips are coated with protective gel material and a cheek retractor is used to keep the lips and cheeks away from the teeth. Clinicians then apply the Zoom whitening gel over the teeth. This gel is scientifically formulated bleaching compound made up of 15 -50% Hydrogen Peroxide, which is activated by specially designed light. So the eye protection is also provided to the patients by an eye protection apparatus includes a selectively darken-able element, such as a liquid crystal panel. Many cosmetic practices now offer DVD glasses so that the patient can watch a movie during their treatment. After the procedure when patient looks in the mirror, he gets amazed at the wonderful result as teeth looks sparkling white which of course will boost his confidence now. 

Click Here for a list of dentists in Glasgow that offer teeth whitening.