Tequila will let me brush his teeth without too much hassle. With Maya, I let her chew on the brush and I wiggle it around her mouth. It's better than nothing.
I use a little tooth brush that has a tip on the end given to me by the vet with the CET chicken flavor toothpaste.
As well, I give Tequila an enzadent dental chew. He loves them, Maya not so much. But the dental chews also help.