1) Closing the gap with veneers. -
The results we've illustrated in our "after" picture for her two central incisors could be made by placing porcelain veneers. The veneers could be used to both idealize the shape of these teeth and also serve as a way of closing the space (the diastema) that lies between them.
2) Another approach. -
As an alternate plan, the same type of result could probably be accomplished by placing bonding. Dentists have been filling in tooth gaps with dental bonding for decades.
Bonding is a much less involved process than placing porcelain veneers. It's also cheaper. The drawback is that this type of fix is not usually as lasting.
The bonding would need to be placed on the sides of the teeth that frame the gap. Their biting edges could then be straightened by trimming across them with a drill (instead of placing bonding there).
Dental bonding that's placed right on the biting edge of a tooth can often be difficult to keep in place. Trimming the tooth back usually offers the more predictable solution.
3) Making changes with the lateral incisors.
The changes we've illustrated for the other two teeth (the lateral incisors) could probably also be made by placing porcelain veneers. If not, then dental crowns would need to be used.
The treating dentist would make this decision based on how much these teeth need to be trimmed back so the crown or veneer placed on them is able to give the proper look (in terms of alignment).
( What is the difference between porcelain veneers and dental crowns? )