"Armchair" diagnosis and cosmetic dentistry treatment plan.
History: This person is missing a front tooth. The tooth that is missing should lie between the teeth marked #1 and #2, and should be similar in shape and size to the tooth labeled #3.
Cosmetic dentistry treatment plan step #1: Perform orthodontic treatment (braces). For the most part, a person's smile is defined by their six upper front teeth. Each of these teeth has a characteristic size and shape and when one of them is missing the resulting asymmetry will be apparent.
The most ideal treatment plan for this case would involve the use of orthodontic treatment. Braces could be used to create a space between teeth #1 and #2, the location where the missing tooth should be. The missing tooth could then be replaced via one of the following procedures (depending on the treating dentist's diagnosis):
The use of orthodontic treatment so to position the person's own natural tooth into the space. (In those cases where the tooth was initially "missing" in the sense that it is not visible but did exist and was present up in the jawbone.)
The placement of a dental implant.
The placement of a dental bridge.
While our "after" picture does not illustrate this result, the orthodontic treatment would also idealize the alignment of the back upper teeth as well as the lower teeth.