Anecdotal. During my dog's checkup's they always say he has too much plaque and we can use those treats that clean their teeth. We've tried several different brands and they've never helped at all.
One thing, does your dog actually crack the treats or can it swallow them whole? We thought the same thing with our large (not overweight, but still 16 lb) cats. Gave them daily dental treats, vet kept saying teeth are bad.
We switched to a new vet during a move who explicitly pointed that out to us, if they aren't actually chewing on and cracking them it does nothing. Got the same treat just made larger, way less dental issues.