My family's cat, Henry, had a bit of gingivitis and the vet suggested he be put on Science Plan Vet Essentials. While not exactly cheap, it did clear it up. I should probably mention that Henry is a bit of a chubster, so it helped with that, too.
With my 5, I opt for the chicken bone approach. Think they get less trouble from the vet than most people get from the dentist, so seems to be working well for us. They get hours of fun out of the bones, too.