The best option to close the gap would be Ortho treatment where you close it with braces Braces you have multiple options like metal clear You could also check with clear aligners Other options would be veneer but depends if it’s a minor gap then can be done but if the gap is too large the front veneers would look too large

Many options available from braces to cosmetic treatments like direct composite fillings or veneers etc. your bite and the extent of gap needs to be checked before advising the correct treatment