3 months since dental cleaning & pom stinks

I love my little pom baby, but only 3 months since her last dental she already has a stinky mouth. She doesn't eat any processed foods and chews raw bone, but her teeth are still plaquey and smelly. When I try to brush her teeth, it's a struggle. She has had liver issues in the past so I'm extremely hesitant to use something that is chemical and not holistic. I can't afford to constantly get this dog dentals, what can I do? Can I learn scaling myself? I'm open to suggestions.