Sure. Tropical people have always had fruit, some had sugar cane. People fought and their teeth were damaged

But dental cavities and abscesses are caused by sugar in your mouth, and bread has always been good at getting stuck between people's teeth, while their saliva converts the starches to sugars

Archaeologists determine whether a skeleton came from a hunter gatherer or a settled farmer by their teeth

Microflora in your mouth - perhaps they did have different, there's no evidence, but if so I would guess that one's mouth microflora changes depending on what one eats

Note that the process that damages teeth is fermentation - where sugar is fermented, liberating energy, carbonic acid. That doesn't happen in the absence of sugar that persists in your mouth