A company that sets up and markets orthodontic CE courses? Personally, I don't think that internship will do much for you. Your networking would likely consist of a few conversations with orthodontists giving you some advice, shooting the s#@* with you etc. Probably not much that is actually useful to you. You could pay extra attention to the CE courses and try to learn from them, but they will probably be over your head. Again, just my opinion, but the only things that the internship has going for it is getting paid and that it is different (although if the schools take the time to think about it...probably not much of a bonus).
Research is nice to supplement your application, but not necessary. You can learn from it, acquire more conversation topics for the interview and if you enjoy it you will be getting an introduction into what may be the beginning of a wonderful and fulfilling career in research...or you will just find out that you hate it.
I guess, in short...I don't think it really matters a whole lot which option you choose. Participate in the one that you think will be more fun.
