Looking at the gallery of White House images, we see that no president, not one, dared to crack even a slight smile until Gerald Ford revealed a few front teeth in his 1974 photo. It looked more like a smirk than a smile, and considering how Ford's presidency came about, maybe it was. Regardless, it established a trend in which all presidents smiled for the camera – until 2009.

Barack Obama, despite his mighty incisors, broke the chain of smiles in his first term photo, choosing to go with a rather somber expression. Then, for his second term: Pow! The president is smiling broadly.

Although vice presidential smiles don't count for much, the Obama-Biden pairing has more dental sparkle than any administration in history. Of course, President Obama seems to flash his ultra-engaging smile at just the right moments, while Mr. Biden sometimes seems unable to rein his in, as was proved in last fall’s vice presidential debate.

Like most things presidential, the question of how a Commander-in-Chief should look in his official portrait began with George Washington. It’s often said that Washington had false teeth made of wood, making smiling difficult. That’s only half true; he did have false teeth, but they were made of ivory and other expensive materials. Yet he did find smiling problematic because, according to numerous historians, his false teeth were spring-loaded, and he feared that if he cracked a smile his mouth might fly open.

You’ll never see a picture of John Adams smiling, because he lost all his teeth and refused to wear false ones. Abe Lincoln was also beset by dental woes, having had his jaw broken as a dentist pulled one of his teeth. Jimmy Carter’s mother, Lillian, once told a reporter that her son had “perfect teeth.” She added that he was, occasionally, “overzealous about flossing.”

In modern times, presidents pose for an official White House photo while in office, and then after leaving office authorize an official oil painting, for which they have an opportunity to reconsider their pose and facial expression. Jimmy Carter’s portrait shows none of the teeth that flash in his official photo. Richard Nixon seems a bit more cheerful in his portrait than he ever did in office. George W. Bush is smiling in both images, but in his portrait removes his jacket, making him the only U.S. president whose official portrait shows him in shirtsleeves.

Barack Obama is the first president to have his official photo taken with a digital camera. According to experts it shows some evidence of being Photoshopped to improve the lighting.

As Mr. Obama begins his second term, he seems to have planted clues in his two official photos to keep historians guessing. Was his somber expression in 2009 an indication of uncertainty in the job? Did he feel overwhelmed by the weight of history as he became the first black president?

Why the big smile in 2013? Is the president still giddy over his surprisingly wide re-election margin? Is he sending a message to opponents in Congress that, like the banks, he’s now too big to fail? And four years hence, which way will the Obama oil painting go: serious expression, or 1,000-watt smile?

It’s too bad the administration didn’t follow up on the suggestion to mint one of those trillion-dollar coins and put Mr. Obama’s picture on it. Would he frown at the size of the national debt? Or, with great confidence, would he smile all the way to the bank?

(c) Peter Funt. This column was originally distributed by the Cagle Syndicate.