This goofy, big-eared kid sure looks like the Mad magazine mascot. According to Completely Mad, the kid’s mug was commonly used in ads across the U.S. in the early 1900s. Mad’s founders made the image their own in 1954, a year after the magazine was born.
The Ritter Painless Dental Co. stood at Flatbush and Third Avenue in Brooklyn. This photo looks like it was taken around 1910.