Lassie co-founders Frédéric Renken and Steijn Pelle moonlighted as dental practice administrators before building. Credit: LassieFor Steijn Pelle, an ideal customer meeting looks very different than your typical startup founder. His favorite focus group: a bunch of dentists in an Invisalign study club.Pelle’s startup, Lassie, sells software to help small businesses run their operations. And not just any small business, at least for now. Specifically, Pelle solves toothaches for dentists across t...