If you use baking soda for brushing teeth there shouldn't be any problems in a long run since i have done it for a month in a while without any side-effects but then returned back to taking very little toothpaste at a time but i should be using soda (sodium bicarbonate) so i'll probably start using it again.
When i was on the soda i took a little baking soda on the palm a dipped the toothbrush in it, didn't need much else, just brush.