It doesn’t matter if a dogs teeth are bright white that makes no difference in the tooths function. Tarter on the teeth is a different story are your dogs gums red and inflamed? You said the breath is not bad does the dog have trouble chewing his food? Sometimes dogs have a skin coloration on the gums has nothing to do with dental health. I would go with what your Vet says. I’m not even sure a dogs teeth need brushed that often? I have never brushed any of my dogs teeth I provide them with things to chew on and I have never ever needed a dental cleaning on any of them!