Thinking of getting arm and hammer extra whitening toothpaste . do dentists recommend this or is there a better one?

Try it: Most Fluoride toothpaste s are acceptable try it some people are allergic to certain toothpaste ingredients and you need to switch if that's the case if you are happy how it works keep it otherwise try another whitening brand.

Whitening toothpaste: All whitening toothpastes rely on being more abrasive to remove superficial stains from coffee, tea, cigarette smoke etc. They do not contain any whitening ingredients.While they may help initially, continued use can make the teeth darker as the outer lighter color is worn away revealing the darker inner structure. Also may make them more sensitive.

Not very much at all: Whitening toothpastes really don't whiten teeth except by removing surface debris from the teeth. You really need to have gels in a tray that stay in contact with your teeth for a minimum of 30 minutes to get effective whitening of your teeth. Tooth paste just doesn't stay in contact with your teeth long enough to whiten teeth.