Take-home whitening kits include custom-made trays and typically use a stronger bleaching agent than over-the-counter systems. In-office teeth whitening treatments by a dentist can cost $300-$1,000 or more, but average about $500-$700. These typically use a high concentration (15%-43%) of fast-acting hydrogen peroxide; the teeth not being treated and the surrounding gums are covered with a protective coating or rubber dam.