X-rays provide information about the structure of the bones and the roots of the teeth, while dental impressions show the teeth's position, size and relationship in the bite. Photographs are an additional assessment tool and help us evaluate the relationship between the dental arches and the soft tissues, such as the lips and cheeks. They make it possible to analyse the symmetry of the teeth relative to the face, how much of the teeth shows when you smile (some people, for example, show more gum), how the dental arch lines up with the smile line, and other key relationships. For this reason, photographs are an integral part of diagnosis and of drawing up a treatment plan.
This answer is for general information. Your own case needs an examination by an orthodontist.