Baking soda (sodium bicarbonate) based whitening toothpastes are less abrasive and friendlier on your teeth than typical whitening toothpastes, but how effective are they at whitening your teeth?
The reality is that baking soda is fairly effective in stain prevention, and not so much in increasing tooth whiteness.
Baking soda is thought to fight tooth staining through disruption of bacterial co-adhesion by converting calcium bridges within plaque into calcium carbonate. This process may also produce carbon dioxide gas which would further disrupt plaque. Both actions are beneficial in reducing stain formation.
Most whitening toothpastes rely on much heavier abrasives to remove stains, and almost all whitening toothpastes contain various types of chelating agents (pyrophosphates, etc.) to disrupt the enamel pellicle and affect stain (and tartar) formation. However, due to the more interesting properties of baking soda in the mouth, sodium bicarbonate based toothpastes are able to have an effect on stains without being excessively abrasive.
Toothpastes in general aren’t a great option for tooth whitening, but if you are concerned with tooth staining and like the peace of mind of a whitening toothpaste baking soda toothpastes are a good option. Be careful about concocting your own blends of tooth powders and toothpastes at home using baking soda; high concentrations of sodium bicarbonate can become more abrasive than you want.