Everyone loves a bright, white smile. Today, whitening agents can be purchased over the counter or you can have your teeth whitened professionally. While you may have success with OTC products, OTC products will not work as quickly or as effectively as having the job done professionally. This is because the concentration of whitening agent available in OTC products is not as high as the concentration in professional products. Also, the trays made professionally are custom fit, allowing for very close contact of the whitening agent to the patients' teeth. Professionally made trays are usually more comfortable than OTC trays as well.