Not a Columbia student but Penn is about the same price. And I can't justify borrowing more than 400k to get a DDS. If you borrow 400k, you can expect that to rise to 500k by the time you graduate. In residency (a paid one that is), you can pay off the interest so that the debt remains at 500k. If you pay for residency, your debt will certainly rise to 700k+.
By that point, if you aren't making anything near OMFS salary, you can expect the drown in debt. You best choice is to do a repayment plan from the government, so long as you borrowed from them.
There's no perspective more important to consider than your financials. Dental school will likely be the same experience and suck no matter if you go to Harvard or Howard. Pick the cheapest school so you won't regret paying a third of your future salary into something because you had better clinical opportunities, brighter classmates or teachers, or better technology.