Despite the presence of several tooth whitening systems, tray-based whitening has become the most widely used type of at-home bleaching products during the last decade. It uses a fabricated plastic tray for comfortable fit over the teeth of a person. Bleaching gel is placed into the tray which is worn for multiple hours a day for some weeks as the effects of the process of whitening take place.

Teeth whitening is a safe and effective method of teeth bleaching but requires the realization that majority of tooth whitening processes will not have the direct supervision of a dental professional. Because of this, a person must be certain about the safety of the bleaching product they are using as well as knowledge of the product in a correct manner. Inability to meet any of the conditions may cause damage or harm.

The dentist and over-the-counter stores offer different varieties of tooth bleaching products. It is not an assumption that available tooth whiteners has been approved by the U.S. Food and Drug Administration. Tooth whiteners are not categorized as drugs and therefore not regulated by the agency.

A set of guidelines that sets the standards for both safety and effectiveness has been established by the American Dental Association. At their own expense and effort, manufacturers can present the result of their product research and trials to the ADA. The “Seal of Acceptance” is issued to manufacturers that satisfy the criteria of their guidelines. Obtaining the seal of the American Dental Association is costly and requires manufacturer's time. This is the demonstration of the company's desire to create quality products.

In the case of at home tooth whiteners, the seal of the ADA is an indication that, when used as directed, tooth whiteners are not harmful to the teeth or the soft tissues of the mouth and is effective in whitening the teeth. In addition, no claims can be made by the manufacturer about their product without the support of a research or they will lose the seal. The ADA's seal is visibly displayed in the manufacturer's products.

Here are some valuable information about "at home" tooth bleaching products:

- Only dentist-distributed products have so far qualified for the ADA's “Seal of Acceptance.” As of this time, over-the-counter products have not yet earned the ADA's seal.

- Ten percent concentrated carbamide peroxide is the only active ingredient present in all home tooth whiteners evaluated in home-bleaching studies which have been awarded the seal. Most over-the-counter at home bleaching products contain the active ingredient hydrogen peroxide and not carbamide peroxide.