Its a case of relapse/failure of treatment. Generally after the gaps are closed a retainer is provided so as to prevent the gaps from re occuring. Relapse generally happens if patient doesnt wear the retainers. So if little gaps have occurred u can go for the re-treatment thats Ortho treatment the results would be faster and this time do remember to use the reatainers. Permanent solutions are there but I personally feel going for something natural always scores over going for something artificial..

Hello! Around the age of 25 the results are slow. So please wear the braces for longer period of time as there is no other solution.

I think you may go for some other option like smile designing say an intentional root canal treatment and crowns,see some other dentist in person just for a second opinion.