Better still, feed them a raw meat diet with bones and cartilage. Raw meat, bones and cartilage are their natural diet and no tooth brushing is required as the bones and cartilage keeps their teeth clean and their gums healthy.
The raw meat diet also helps with the other end of their GI tract, if you know what I mean.
My 10 lbs Lhasa Apso can not handle bones! She chokes on them. All she gets is ground beef and scrambled eggs in small quantities. I can set my clock with her bowel movement habits. She has never needed to visit a vet in 13 years. Never been sick, not even stomach upset. She gets daily walk of about a mile.