You might be able to space out the brushing a bit more by using good dental food.

OR, get Hill's Dental dry food and some MediTreats, and use those as treats (no other treats allowed, that is).

They will really help keeping the teeth clean.

I have had my one cat three years and the other two years, and no cleanings needed yet (and I don't brush their teeth either).

Ask your vet about this, too.