It seems to be the common perception that in the post-apocalyptic world everyone will be happily filthy and there will be a beautiful sea of unwashed masses who eat grubs and live in abandoned basements.
This hypothesis overlooks the fact that for the last 100 years or so people have gotten used to being clean and coddled. The issue of personal hygiene is not simply about comfort, it’s about safety and survival. Do you want to be the asshole who died from an infected pimple or an abscessed tooth?
Many of the daily grooming habits we’ll have to do without are things we’ve grown so accustomed to physiologically, that once they’re removed from our daily lives there will be a noticeable and traumatic impact.
And they grew up on a steady diet of liquor, and rats, and found organic materials.
In other words, they, like the folks in real life downtrodden areas, are just more rugged than we who visit the dentist and doctor every six months and cry about the possibility of getting a root canal. That root canal, which will be under general or local anesthesia and comes with a prescription for heavy pain meds, is much preferable to waiting until the tooth just rots until it’s ready to fall out or getting it pulled out by a friend. That root canal is also preferable to the infection that a rotting tooth can cause. An infection that you can die of when left to spread untreated.
In the post-apocalypse world, brush your teeth. Even if you don’t have access to toothpaste, guard that toothbrush with your life. Also, in a pinch, you always have the option of finding a Chew Stick (cinnamon should be easy to find).