Robert Siegel

The opioid epidemic has been fueled by soaring numbers of prescriptions written for pain medication. And often, those prescriptions are written by dentists.

"We're in the pain business," says Paul Moore, a dentist and pharmacologist at University of Pittsburgh School of Dental Medicine. "People come to see us when they're in pain. Or after we've treated them, they leave in pain."

How well do we understand and act on probabilities that something will happen? A 30 percent chance of this or an 80 percent chance of that?

As it turns out, making decisions based on the odds can be an extremely difficult thing to do, even for people who study the science of how we make decisions.

Federal officials have announced that a young Mississippi girl, once thought to have been cured of HIV, now once again has detectable levels of the virus. This is a setback not just for the child, but also for hope of eradicating HIV in infants with a potent mix of drugs at birth.