It looks like MOST of the descriptions people are using for “richness” are pretty vague, which I find to be weird since we actually have readily available numbers.
Median US individual income is $26,695 . Unless you want to claim that half of Americans are “poor” or lower class, you should probably start your middle class no lower than that.
(ETA: For a full-time worker over the age of 25 it’s $39k, so you could maybe push it up to that, but it disregards a lot of people who are stuck in part time jobs, or are kept working at just below full time so that they don’t have to be given benefits)
10%ers start at $82k. I think it would be silly to say someone in the top 10% of US earners isn’t rich. Almost all STEM LWers I’ve met either make well above this, or work for a non-profit.
After they finish doing the fillings, they file the new material down to fit your bite. You might recall them having you bite down on a piece of paper and then they’d sand away all the parts that were hitting. The more fillings that get done at once, the harder it is to get this done properly, I think. If certain parts of your filling or teeth are hitting before the other parts are when you bite down, or if they are otherwise not fitted well, it can cause pain throughout. (They are also more likely to fall out then)
Source: Personal experience with bad fillings.