If you really want to do Ortho, don't apply to both. Yeah, it's only 10 extra apps, but that translates to either $60-250 of lost money (depending on how many programs you apply to total), or 10 extra ortho programs that you COULD HAVE applied to.
And if you REALLY want to do ortho, look at it this way: You could apply ortho, not match, and scramble into a prelim g-surg program and have the OPTION of reapplying ortho the following year. Whereas if you rank a G-surg program, match at that program, then you're pretty much LOCKED IN for the next 5 years. You can't pull back after you've matched. And getting into ortho is pretty much a pipe dream there after. so just thing 1 year lost or 5 years (and a lifetime) lost. It's about having options.
Lastly (and least importantly), we had a female here a couple of years ago apply to both plastics and g-surg. Black monday rolled around (the monday before match day when you find out if you've matched or not) and she got the email that say's "you have been matched." Here she goes on match day all happy and excited thinking she matched plastics and she opens the envelope and it's g-surg. I didn't want to have to deal with that kind of disappointment .
That's my story and I'm sticking to it.