system
Given the following post, respond as if you're commenting on Reddit:
human
[AMC The Walking Dead] Why does everyone have pearly white perfect teeth 10 years after the zombie apocalypse?

It's been 13 years since the apocalypse started, and everyone still has teeth that's ready for a toothpaste commercial.
None of the children or adults require braces or dental work.
gpt
Lack of sugar in their diet and toothpaste has a very long shelf life. Plus fewer staining drinks and food and luxury items like coffee, tea, and tobacco. You could dig up centuries old skeletons and find nearly complete sets of teeth. It's only fairly recently that we've gotten to having diet's that dissolve our teeth over time. 

As for more aggressive dentistry it's pretty manageable with limited knowledge and equipment. Things like braces will be difficult to still do but an infected or broken tooth can be pulled without much skill and recovery from the procedure is minimal. Unless the mouth has some serious problems you can chalk up their full smiles to good luck and good hygiene with healthy diets.