Choice of 1hr or 30-minute teeth whitening treatment. Benefits: Teeth whitening helps to restore a smile tainted by discolouration. In-office teeth whitening produces the fastest results. How it works: Significant colour change in a short period of time is the major benefit of in-office whitening. This protocol involves the carefully controlled use of a relatively high-concentration peroxide gel, applied to the teeth by the dentist or trained technician after the gums have been protected with a paint-on rubber dam. Generally, the peroxide remains on the teeth for several 15 to 20-minute intervals that add up to an hour at most. Those with particularly stubborn staining may be advised to return for one or more additional bleaching sessions or may be asked to continue with a home-use system.