Yes, teeth whitening does work on natural teeth that have experienced some surface and/or subsurface stains from eating, drinking or smoking things that leave stains on or in the tooth enamel.
Teeth Whitening DOES NOT whiten Veneers, Crowns or Fillings. Any company that can promise you that, its complete BS.
All of our customers have been very pleased with their results from our home whitening products as well as our products for professional use.