From the information you have given us here, It may be possible to put bonding or a porcelain veneer on the outer aspect of this tooth to make it appear less crooked and more natural in the smile. I do not advise this as a first choice as it could over-contour this tooth and make it more susceptible to cavities and gum issues etc. My advice would be to reconsider an orthodontic consult if even just to re-position this tooth to correct the occlusion and appearance. If orthodontic treatment is not an option, then bonding or a veneer can treat the aesthetic issue without treating the issue with the general positioning of this tooth. In my opinion, a full crown here to correct the positioning would require significant removal of tooth structure that can compromise the tooth in other ways- I do not think that would be a very good idea. Hope this helps.
As I don't know the specifics of this case I am not sure, but I am not convinced yet that it can't be corrected with braces. If there aren't any underlying issues, maybe they can refine the orthodontics case to slightly extrude this tooth? Have you discussed the issue again with your orthodontist? If braces are not possible, then for pure aesthetic purposes a veneer or simple bonding are possible options to extend the length of the tooth to match the other central incisor. Hope this helps!
Invisalign should typically work regardless of the presence of fillings on anterior teeth, and it shouldn't usually affect intact fillings. However, if these fillings are defective, or they splint the teeth together (such as with a fixed retainer) then this is a contraindication. If your general dentist has not seen any ongoing dental issues and clears you for invisalign / orthodontic treatment, I can't see any reason not to proceed based on the presence of these fillings.
I do not believe whitening the back of the tooth will have any significant impact on the shade of the veneer, nor do I think the porcelain of the veneer and crown should discolor significantly over time.
This really depends on the Dentist's technique while removing it. In my opinion, If there has been no other damage to the teeth since the bonding was done, and the dentist removes it carefully, being diligent not to remove any tooth structure, then the tooth structure and gap should be similar, so long as the teeth haven't drifted at all since the bonding was done. Hope this helps.
