Well it isn't supposed to be the Boy Scouts, but it isn't a gulag either.

There has to be some kind of deterrent that makes people not want to recidivate.

There are all kinds of opportunities for people to upscale in prison, if they want to; books, educational programs..

And @helenwheels, if the people you know were in prison for drugs/alcohol fused/related crimes then they probably weren't taking very good care of their teeth in the first place.

I invoke my right under the 5th amendment of the United States constitution and decline to answer the question.