Bridge and porcelain crown on front four teeth or implant to replace front tooth?

Your dentist has given you good advice.  That being said, you could go either way.  . If you are completely happy with all of your teeth, then I might suggest the single dental implant with porcelain crown.If you want your teeth straighter and protruding you then the bridge route with an additional crown on your left lateral incisor would accomplish that.However, all that being said, I think you have a beautiful and natural looking smile, and as such, I would opt for the single tooth implant.   But, make sure that the dentist who does the implant is very experienced doing them in the front of the mouth, as that area is much more difficult to get a great esthetic result than implants in the side or back teeth.  Also, would strongly advise using a zirconia abutment and zirconia-porcelain crown over the implant to give you the best color match.

An implant is usually the standard of care. When a permanent bridge is made the teeth that support the bridge have to be prepared with the drill and all of the enamel is stripped off of the teeth. A single tooth implant is difficult to place in the central incisor area and a bone and tissue graft is normally needed. You need to have and implant specialist, I would suggest a periodontist and orthodontist evaluate your situation prior to any decisions. 

Today, dental implants really are the standard for replacing missing teeth. Bridges tend to stress the remaining teeth and if one part fails the entire bridge often needs to be redone. With implants, only what's missing needs to be replaced. Once you have a crown on a tooth, there's no going back, you'll always need a crown.As for the alignment, I would suggest a consultation with a board certified orthodontist first to see what your options are, and because it is also the more conservative treatment. You should also see an oral surgeon to determine if there is enough bone in the right areas to do an implant. Even if there is not, it's possible to do bone grafting in order to get enough bone. It's key that the orthodontist, implant surgeon and restorative dentist plan the case together in advance and stay in close communication. If this doesn't happen, problems can occur.