I had a really difficult time brushing my pup's teeth. So I use dental wipes instead. They've worked really well for us. In fact, Yoshi skipped his dental 2 months ago. This is the brand I use:
Amazon.com: 8in1 D.D.S. Dental Wipes, 90-Count:...
I'm not sure if it's the best brand, but it works for us.