management of the gap will depend on many factors. Was the gap present from childhood or has it developed later? do you have any habits?
in a nutshell, you need a proper evaluation before the best course of treatment can be decided keeping in mind your needs, time and cost.
The best treatment option would be orthodontic correction (braces) as it would not require the physical alteration of any original tooth.
The other options are, ceramic / composite veneers