I agree you need more than one tooth brush
Try everything - when you find something that works one day, it won't the next
. Just be clear that brushing is not optional, and most days it should be possible to avoid tears
with a bit of inventiveness
.
I have used all the previous suggestions, and here are some more:
give a choice of toothpaste,
take turns - it is my turn if the toothpaste is minty (adult) - if it they want a turn I keep reminding about brushing not sucking... and I always have to get a turn too
run the tap and let them hold the brush under, or put the toothpaste on,
count teeth,
'find' bits of all the things they ate today,
give the teeth names,
ask them to make faces - e.g. cheesy grin, lion roaring,
brush them somewhere different e.g. in the bath, or while looking at a book,
try again in 5 mins,
if all else fails I'm afraid I resort to pinning them down across my lap and just doing the best I can as quickly as possible
.