Almost immediately, but some of this is artificial. This is because there is a dehydration effect from the glycol base in Dental White. This base is hygroscopic which means it draws up water. Therefore, the teeth will be whiter due to the water being removed from your teeth. But, by continuing the peroxide can easily get into the teeth producing whitening in time. The gel substance works very quickly, but your progress will depend on the nature and depth of your stains. The process should take from 2-3 weeks for yellow stains and perhaps months for blue gray tetracycline types of stains if at all. Most with tetracycline staining will wear it for 2 months, if nothing changes, then they will discontinue use.
