It will look like something this
The main feature of this ball is that it has barbs on it similar to those weed thingies that stick to your socks and were the inspiration for Velcro ... and ... it dissolves in your saliva releasing an anti-bacterial agent into your mouth (with minty breath freshener).
And this micro-encapsulated anti-bacterial agent is time released by varying the size and/or properties of the barbed capsule. You use the mouthwash in the morning and at night ... then throughout the day and night the capsules (stuck into the tissue all over your mouth and particularly where they are protected from turbulence, i.e. where the bacteria like to congregate) break open and kill the little critters.
Why bother with such a mundane idea?
Wait a minute pardner! This is a world beater or I wouldn't be writing about it. What we have here is the end of 90% of dentistry. For if you can alter just slightly the environment inside of your mouth, any individual can become one of the "lucky" ones who never seem to get any cavities (like my mother and next younger brother). They have ... perhaps ... just a tad more acidic saliva which kills off bacteria in their mouths faster than they can breed. I, on the other hand, have saliva that is just behind the exponential growth curve. So my teeth have not faired so well. What I wouldn't give for a new dentition at 35 years of age genetically programmed into out DNA! Incidentally, the record for number of dentitions is, I believe ... 5! That is, somebody got five new sets of teeth in his life whereas we all regularly get just two.
So where is my mouthwash? If they can't do this, they might as well call it a day and find something a little less nano that they can get their hands onto ... like socket wrenches or tire irons.