Your symptoms may be resulting from inaccurate occlusion (bite) on your new crown or worse, a pulpitis requiring root canal to resolve. Go back to your dentist and have him evaluate your pain. If bite is the cause, the cure is easy and quick. Good Luck!
Not sure what "steel contraption" you are speaking about but relapse is very common after orthodontic treatment. And yes, in some cases you could relapse all the way back to your original appearance. If the orthodontist placed a fixed retainer on the inside of you front teeth, you can replace that with a traditional removable retainer that is worn at night to maintain tooth position. Hope that helps!
While the KOR Max Ultra does have the additional inital in-office treatment and a longer at-home protocol, my experience is that it is not necessary except in more difficult darkly stained or teracycline type cases. Most other type cases respond very nicely to the shorter protocol. Talk to your provider about this and get his/her opinion about your specific case. Good Luck!!
Sorry to say, but it appears you are suffering from relapse. This is a common occurrence when patient's do not where their retainers as prescribed. See your orthodontist now before the relapse worsens. He may be able to re-align your teeth in a short period of time then make you a new retainer. Best of Luck!
In this day and age I would never recommend a bridge where the abutment teeth are unrestored, without first exploring the possibility of an implant restoration. It is a more conservative, and in many cases, more predictable means of replacing your missing teeth. As far as the grafting is concerned, many of my patients have expressed those same fears but in reality, bone grafting is a relatively painless procedure and will provide you with the bone necessary for proper implant placement. Find an experienced periodontist that does alot of these procedures and discuss the possiblity of just one implant with a two tooth "ovate" pontic cantilever. This may give you the best cosmetic result. Good Luck!