R.O.C.S. Whitening is a polishing toothpaste, not a chemical bleaching treatment. Its main role is to polish away surface stains that build up from coffee, tea, red wine or smoking, so teeth look lighter and smoother after regular brushing.
The key polishing ingredient is silicon dioxide microparticles. They are fine abrasive particles that help lift and buff external discoloration from the enamel surface. The formula also includes the Mineralin complex, which is described as helping maintain strong hard dental tissues while a whitening toothpaste is part of daily oral hygiene.
Because this is mechanical polishing rather than bleaching, it will not change the natural colour deep inside the tooth. It is best suited to external surface stains, and the effect builds up gradually with consistent use. If you want a noticeably whiter smile from changing the inherent tooth colour, you would need to look at chemical whitening options. For people whose teeth quickly lose brightness between professional cleanings, this type of paste is a practical way to help keep the smile looking fresh.