It's awesome that you've gotten her used to brushing
. One of the few things approved by VOHC is Healthy Mouth - so that's what I use. Their website is full of info if you want to read about it.
Some people here seem to do yearly dentals while others do them when their vet says it's time.
It seems like the majority of dental issues comes down to genetics at the end of the day...seems to be the case w/ humans too.