For what I have read and taught in vet tech school only special formulated "dental" dry food helps teeth. Otherwise dry is no better than canned for oral health. The dry fractures before it gets a chance to do anly cleaning. Also, many cats just swallow dry without chewing. Mine will not even chew the relatively large pieces of Evo Cat and Kitten dry food.
Regarding testing. I test each of my cats before each shot. otherwise once I find a good dose I seldom test between shots. That is unlike many here who always seem to do tests between shots in addition to before shots.