The best teeth whitening products among the rest. Among the newest whitening products available are whitening rinses. Like most mouthwashes they freshen breath and help reduce dental plaque and gum disease. But these products also include ingredients such as hydrogen peroxide which whiten teeth. Manufacturers say it may take 12 weeks to see results. You just swish them around in your mouth for 60 seconds twice a day before brushing your teeth. However some experts say that rinses may not be as effective as other over-the-counter whitening products. Because a whitening rinse is only in contact with the teeth for such a short time -- just two minutes a day compared to 30 minutes for many strips -- it may have less of an effect. Tray-based Tooth Whiteners Tray-based tooth whitening systems purchased either over-the-counter or from your dentist involve filling a mouth guard-like tray with a gel whitening solution -- which contains a peroxide-bleaching agent -- and wearing the tray for a period of time generally from a couple hours a day to every day during the night for up to four weeks and even longer (depending on the degree of discoloration and desired level of whitening). In-Office Whitening In-office bleaching provides the quickest way to whiten teeth. With in-office bleaching the whitening product is applied directly to the teeth. These products can be used in combination with heat a special light and/or a laser. Results are seen in only one 30- to 60-minute treatment. But to achieve dramatic results several appointments are usually needed. However with in-office bleaching dramatic results can be seen after the first treatment. This type of whitening is the most expensive technique.