I brushed my very first Rottie's teeth because she has medical issues and couldn't eat raw <dog> food and bones. I never brushed my Lab's teeth who was alive during that same period and did outlive my first beloved girl. My Lab got raw bones and he never had a dental.
You can train a dog to tolerate or accept teeth brushing but it takes daily practice from puppyhood with very high-value treats so the puppy associates the tooth brush and the mouth handling with goodies. Most dogs will learn to tolerate brushing eventually if started this way and IF you avoid punishment and drama with it.
But it will usually not ever be something the dog really likes.
"Dry food cleans teeth" is a marketing myth.
Dental chew products may or may not work for any given dog.
Nails....same way... it's taken us a year and and half to get my youngest Rottie to accept us doing her nails and at first we couldn't even do more than one nail. Originally as a baby puppy I would hold a raw turkey neck for her to be pre-occupied with and hubby would dremel, but she quickly got too strong for the turkey neck thing to work.
But we still made a game out of it using very yummy treats like fish and cheese and hot dogs and every couple of days we'd take out the dremel and one person would treat and one would dremel- sometimes we didn't even get through one nail. One nail touch with dremel, or one actual dremel trim of a nail - she gets a goodie. Try to end before she struggles or pulls away.
Sometimes we went back over the same nail or didn't get them all over several days, but the biggest thing was that she was learning that the whole thing was harmless.
So it's taken us til this point actually, to get to using something like cut-up apple cubes and carrot pieces - which are not as automatically valued as something meaty and stinky - and we can actually do a whole set of nails with her including dews. But the trick of it was pretty much every other day, we tried, if only for a minute, and made it a game and tried to end happily or at least neutrally. We didn't yell, or hold her down.
Now both dogs really like when we get the dremel tool out and will go zooming over to the couch and bounce up onto it to start the nail game!