I've hardly ever brush my dog's teeth, even though I know I'm supposed to do so....in fact, I have brushing my own teeth, especially when I'm half asleep at night.
But, just as in humans, stinky breath isn't normal or healthy, and gum disease is an all-too-common doggy ailment. Brushing every day is the best prevention. But choosing hard food over soft can also help scrape your dog's teeth clean as he chews, and it's less likely than soft food to get stuck between teeth. Chomping on chew toys can also have a cleaning effect. If you're considering treats or food formulated for oral health, ask your vet if any of the products would be helpful.
Info from dogage.com