Orthodontist or Dentist first?!

About 3-4 years ago I broke my "invisalign" retainer, and never got it replaced. Not long after that, the cap on one of my Lateral Incisors broke for the third time (both are too small and I'll have to get implants one day). Now the space between my two front teeth is starting to spread and I know I'll need a retainer of some sort to push them back together, the problem is, who do I go see first? The dentist to replace my broken cap, only to have the retainer push the teeth back together so I'll need another cap? Or should I go to my orthodontist first?

I started going back to the dentist last year, and he has been so busy (poor guy) that he just tells me that it's a problem, but not what I should do to get it fixed.