This type of teeth whitening usually requires two visits. At the first appointment, impressions will be made of your teeth to fabricate custom, clear plastic, trays.
At your second appointment, you will try on the trays for proper fit, and adjustments will be made if necessary. The trays are worn with special whitening solution given to you by your dental provider. Depending on which whitening system you choose, the bleach can be a different strength.
It is normal to experience tooth sensitivity during the time you are whitening your teeth, but it will subside shortly after you have stopped bleaching.