Ate adult roach

Relatively small (about 16 in) 9ish month old ate whole adult roach... What are the risks? Anything that can be done?

About the only risks I can currently think of would be paralysis and impaction. What you don't want to have happen is your beardy dying or suffering from temporary or permanent paralysis(since the large food puts pressure on the spine). So, try and get your beardy to not put its weight on its belly and let it hang. You can do this by placing it on a towel and where your beardies belly would be, cut out a hole in the towel large enough that your beardies belly can fit and hang without any weight on it. As for impaction, I've heard to give non solid foods like pumpkin purée, non solid prune products, and unsweetened applesauce, with a couple others too. However, I'm not educated about the impaction so someone like kingofnobby or Drache613 would be of more help as they are knowledgeable when it comes to impaction relief.

I don't think the risk of impaction is all that high with a 16in dragon. I wouldn't offer adult roaches as a habit yet, but it probably won't cause an issue, especially if it was chewed up pretty well. My adult dragon is about 19'' and eats the adult roaches all the time with no problem. I would offer some extra water via drops on the nose for a bit as the hydration may help pass it through but I wouldn't be too concerned. Look out for lethargic behavior, immobile legs, or lack of poop on a regular schedule (4-5x longer than usual).

I agree, I was just pointing out any POSSIBLE risk and solutions, though I don't think it is likely to get impacted either.