My dog has nasty teeth and breath. What should I do?!?

My dog is really tiny, she is 5 years old, though. Her teeth are going to start falling out, escpecially if I don't do anything. (I think her front teeth are those kind that don't have roots). Her breath is really nasty too. I really don't want to brush her teeth. I've tried and I really can't do anything in there since she doesn't let me and her mouth is so small (even if I use the tiny tooth brushes) Does anyone have any ideas on anything else I can do?! I would really appreciate the help. and also, would her not having good teeth shorten her life expectancy? She is the best dog ever and I would really appreciate it if anyone could help.