Crowns falling out from dental implants, posts in place. Any suggestions?

I have had dental implants done twice in the same area, upper left hand side. There were two implants done with three teeth. The first implants lasted 9 years and I had no problems until they fell out. One of the posts was gone and the other one was broken in half. The second time, in another state, the implants were perfect for 5 years and then, out of the blue, the teeth just came off yesterday. The two posts are still in place, seemingly strong. I don't know who to call.