Doctor Zebra’s Medical History of American Presidents gives the lowdown on all 43 commanders-in-chief. Excerpts:

• George Washington really did wear dentures, made of hippopotamus ivory, seahorse ivory, and lead. “Other sets used the teeth of pigs, cows, elks, and humans.”
• A dentist once broke off part of Lincoln’s jawbone while pulling a tooth — without anesthesia.
• JFK was diagnosed with Addison’s disease in 1947 and given less than a year to live. In October he was actually given last rites.
• Reagan quit smoking easily, which can be an early sign of Alzheimer’s disease.
• George W. Bush has creases in his earlobes, which may be a marker for increased cardiovascular risk. No one knows why.

The Constitution explains what to do if the president dies, but not if he’s incapacitated by illness. “Note the heavy burden of disease that has afflicted our presidents,” writes the anonymous doctor. “We have been very lucky indeed.”