Nerves can definitely regrow. Slowly (1mm/year afaik), but it's definitely possible. I took off the top 1cm of my thumb with a table saw a few years back, had it stitched back on, and I'm just regaining feeling in parts of it now.

Heart muscle repairs quite well... as do nerves.

Have you got a single source for your claims? You can literally google "heart muscle repair" with hundreds of results refuting you.

Uh, all those articles are about experimental stem cell treatment. Absent a medical intervention, heart tissue damage from a heart attack can't be reversed. You can strengthen your heart the same way a healthy body can with exercise, but you can't regrow lost tissue. No more than you can recover from brain damage.

Your teeth absolutely can repair themselves, and are in fact constantly doing so using much the same resorption-remineralization processes that your bones use.

Many things can tip the scales in favor of the remineralzation side. Diet, cleaning, and increasing saliva circulation appear to be the main ones.