Some would argue that orthodontists have less stressful days since they don't do much of the work and delegate everything. However, having a ton of kids and teenagers run around all day long would stress me out. I would much rather be staring the orifices of canals all day, seeing less than 10 patients a day. Not to mention endodontists have just about the lowest overhead of any specialty. Low overhead, small staff size in the office, few patients = low stress.