It’s not too abrasive for teeth. 
Just get plain white toothpaste, like Pepsodent or something, not all the fancy tartar-removing, etc. stuff.
I just saw it and was paying attention because I had seen this thread. Another Primate has it right. The only thing I wanted to add is that he said you can use it on any kind of silver except jewelry that has “antique elements” (or something like that), including stones.
When I was a kid it was ‘Bath salts’ crystals (which I think are a mixture of Salt and Bicarb or something) that we would use for this method.
I will never try it again; I tried ‘cleaning’ my mother’s expensive silver pendant and it ruined it - leaving it pitted and destroying some of the delicate enamelling.
Why not just use silver cleaning stuff from the store & be safe?