Once a week seems good and I think is better for your skin. I think our bodies do have a lot of good bacteria and oil on them.

Do brush those teeth more often. I tend to skip or forget brush. Please try to brush once or twice a day or at least use a good mouth wash.
I have had to deal with cavities, teeth needing pulling, and crowns.
Painful, very expensive and now hard to chew food.
I found it helps to keep alot of tooth brushes around everywhere you might could brush. Also, using electric and manual brushes creates some variety.
Just had another idea, try differnt types of toothpaste. I don't really like the one I am using, but it is supposed to be good for your teeth and gums.. Of course it doesn't do much good if I don't use it!

HAPPY BRUSHING!