No – They actually have a reverse effect, with continued use their abrasiveness removes enamel allowing the darker under structure, dentin, to shine through. Over time this can cause extreme damage not only to the necks of your teeth but to the marginal gingival tissue which recedes.
Whitening tooth pastes are very abrasive and are helpful in removing "extrinsic" stains on teeth or stains on the outside of your teeth.
Whitening, works more like Oxy-Clean using a safe derivative of hydrogen peroxide to remove the stains from deep within your teeth.
If you have sensitivity or recession, whitening tooth paste is not good for you.
Most whitening toothpastes do not deliver what people desire. Many have abrasives in them that can dull the finish of dental restorations, but CAN make the natural teeth slightly lighter in color IF the discoloration is a superficial stain. However, the effects are short lived.
Most people have intrinsic (internal) discolorations that whitening toothpastes won't affect. To truly whiten teeth, a process supervised by a dentist is the best.