Crest Whitestrips - These are a proven option to whiten teeth, if teeth are straight and used for 14-21 consecutive days. Skipping days will reduce effectiveness even if the same amount of product is used over a longer time period. The strips tend to slide around on teeth, especially lower teeth, which makes them less user friendly than the other methods, but they are the least expensive. These are best indicated for teeth that require minimal whitening.
Tray Whitening - Molds of your mouth can be taken and trays made that perfectly fit your teeth. Gel can be placed in the trays and worn for about an hour each day. These are much easier to use than Crest Whitestrips, and can produce better results in people with overlapped teeth. Once the trays are made additional whitening gel can be purchased separately years later and used with the trays over and over, bringing the long-term cost per use closer to the Crest Whitestrips.
Whitening facts - Only teeth can be whitened, not existing dental work. Fillings usually take on part of their color from the surrounding tooth, so small fillings usually aren't noticed after tooth-whitening. Crowns and major restorations may look darker than the newly whitened teeth, and may need to be replaced after whitening to match the new tooth shade. Also, all whitening methods can cause tooth sensitivity. If teeth become very sensitive while using Whitestrips or tray systems, you can whiten every other day or every third day until sensitivity decreases. While maximum whitening is achieved with most frequent use, excellent results can be obtained in most people even if they space out their whitening schedule. Also, results will vary. While yellow colorations usually whiten more than grey colorations, there is no way to predict how white your teeth will get with any method, and in some cases very little whitening occurs. Overall, however, most people are delighted with the results.