There are many factors that can stain teeth (e.g. nicotine from smoking, sauces and drinks such as red wine, tea and coffee). Absolute White Whitening Gel Pen contains a quick drying gel with active oxygen bubbles which when applied to teeth will safely begin to remove apparent stains. It is easy to use. Whitens teeth upto 2 shades whiter in 1 week if included in regular regimen. Results may vary.