Something I came across the othe day.
In 1930, there were 71,000 dentists. At the time. we had 1 dentist per 1,700 people (the US population was about 120 million). Today, we have over 300 million people in this country, with about 180,000 dentists - surprisingly, the ratio for population to dentist is still about 1,700 to 1. The ratio might have gone up or down a little, but it stayed close to 2,000:1. Obviously ADA and other interest groups for dentistry are keeping these numbers in check to protect the profession; from preventing more schools being opened, or forcing foreign dentists to train before they work in this country, etc.
There are studies that indicate that this is the best time to practice because of high retiring rate in the profession. However, it doesn't really take into account the issue of misdistribution of dentists (California versus Maine), or the fact that the average patient's purchasing power can change due to the national or local economy, or even states cutting dental benefits for their residents, like we have seen in recent years.
Bottom line, the demand for dentist is driven by the shortage. There are almost 1,500 U.S. communities that have shortage (according to federal estimates). That's about 10% of all U.S. communities. There are stories where patients travel over 100 miles to see a dentist in some parts of this country.