How long do the results last?
Whitening is not permanent, but it is long-lasting. Most patients keep their result for one to two years, and some considerably longer. The variation comes down almost entirely to diet and habits rather than to the whitening method itself.
What makes teeth darken again?
Coffee, tea, red wine, dark fruit juices and tobacco are the main culprits. Enamel is microscopically porous, and coloured molecules gradually settle into those pores. Ageing also plays a part: enamel thins over time, allowing the naturally yellower dentine beneath to show through.
Making it last
Rinsing with water after strongly coloured drinks, using a straw where practical, and not smoking all help significantly. Regular professional cleaning removes surface staining before it sets in. Many patients top up with a short course of home whitening every year or two.
An important note on restorations
Whitening only works on natural tooth structure. Crowns, veneers and fillings keep their original shade, so if you have visible restorations they may need replacing afterwards to match your new colour. Your dentist should plan this with you from the start.