ADA Seal of Approval. As long as a whitening material has been tested by the ada, they will allow their seal of approval to be placed on the material. This signifies that the manufacturer has met some rigorous criteria for allowing the product to be used as it is advertised.
Nice question... There are several. From the stores, crest whitestrips. From dental offices there are many as they are mainly made by dental manufacturers. These dental office products include the companies of ultradent, pola, phillips discus zoom, and others.
OVER THE COUNTER. Crest is a reliable product. Over the counter products have low concentraction of bleaching agents.