The whiteness that you achieve through laser teeth whitening would last forever, if you never ate or drank staining foods such as curries and red wine, and didn't smoke either.
So the length of time the whitening lasts would be varied depending on your lifestyle, and any loss of whiteness would be gradual over a fairly long period of time.
If you use a whitening toothpaste twice a day (morning and night) after treatment, you will keep re-staining to a minimum and maintain the whiteness of your teeth for longer.
Whitening toothpastes simply remove surface stains and are good for teeth that are already white. They WILL NOT whiten teeth however, only help remove debris that collects on the surface enamel.
We would recommend a laser teeth whitening top up application every 4 months to maintain the natural whiteness you really want. This is a 30 minute treatment only, and will cost a maximum of £60.