Depends on what you mean by regenerate. If you want to "remineralize demineralized enamel areas" [1] then check out nano-hydroxyapatite toothpaste that's been available for more than 40 years.
I think even if we could it would be too expensive to be worth it. And our society has grown brittle. We’re not interested in revolutionary technologies. If it put any dentists out of work or made them less money there would
Be a huge push back.
Need more stem cell research. Growing a tooth is very hard to do so far.