Captain Obvious narrowed his eyes and frowned. On his monitor, a study  recently published in Acta Ondontologica Scandinavica.
Our intrepid hero – champion of common sense in research and the enemy of wasted money and time – read the abstract, and then he read it again. It had been years since his Ridiculous-Sense had fired so fiercely!
The study involved sixteen participants assigned different toothbrushing “regimes.” Some used standard fluoride toothpaste, while others used a high fluoride paste (5000 ppm, over three times more than standard). Some brushed two or three times a day; others massaged toothpaste into the cheek-side surfaces of teeth and gums in addition to brushing twice daily. Researchers measured how much fluoride members of each regime group retained in their “plaque” and saliva. They also measured changes in plaque pH after a sucrose rinse.
And what did they discover?
Those who put more fluoride on their teeth more often wound up retaining more fluoride.
Brilliant, huh? Thus spake the authors:
A third application of toothpaste is increasing the F [fluoride] retention and toothpaste as a ‘lotion’ and massaging the buccal surfaces with the fingertip may be a simple and inexpensive way of delivering F a third time during the day.
(This, of course, is no matter to the toothpaste makers. Just recently, Colgate announced its development of a prescription-only paste  containing 5000 ppm fluoride. No word how they feel about rubbing it into your teeth and gums.)
As just as more isn’t better when it comes to fluoride, so, too, with toothpaste in general. As we’ve noted before , extra toothpaste can wind up damaging the enamel of your teeth, leading to tooth sensitivity and a greater risk of decay.
Fortunately, it’s not toothpaste that keeps your teeth clean; it’s the physical act of brushing that breaks up the biofilm (“plaque”), keeping the microbes it’s made of from causing decay.