The best information on the topic of OMS, Endo, Ortho, Perio salaries is to be gained from the ADA survey center. "Income from the Private Practice of Dentistry" surveys are done by the ADA for general dentistry every year. In the year 1998 and 1999, the ADA released a special set of statistics done on each of the specialties separately. Salaries were broken down for each individual specialty a hundred different ways...for group practices,solo practices, incorporated ones, sole proprietorships, broken down by national region, by years since graduation, by hours per year or per week, full time, part time, etc...
I've read the OMS, ENDO, and PERIO one through my health science library...anyone can get them from other dental schools even if you don't have them at your own school via interlibrary loan...
At least in the 1998 publications, OMS made more money overall than Endo, Perio, or Ortho, contrary to what Gavin says. And it CAN'T be argued that its because OMS work more hours, because in the surveys it was broken down by the hour, not year...
I must add that endo was only about 7,000 per year less than OMS, and one could argue that a different survey sample may have yielded different results...and there will always be individual practices that break the standard...but still, in the only scientifically valid survey done, OMS made more than Endo overall...