"Diet = dental health" is bullshit. My partner was raised sugar-free and has horrible teeth with many cavities. So does their entire family. I was raised on a diet which included many forms of sweets, and I have never had a cavity. Same for my entire family. Genetics or other biological predisposition seems to be a major factor. Diet might help a bit, but don't expect any magical effects.
Eliminate things bacteria can efficiently metabolize, consume things that humans can efficiently metabolize. Namely, eliminate saccharides (sugar, plant starches, etc.) and get your calories from fat instead. Improved dentition is only one of many benefits.