Upper tooth are lil front. For my case?

I went to dentist for my upper tooth which are little front and there was a gap in lower incissors. So he put braces..it's been a month now. Then he realised that one lower incisor is missing congenitally missing teeth. Now he told to either extract 4 tooth to make space and place a artificial tooth using implant or crown or just to file the upper tooth as much as possible for space and close the lower gap with braces. Confused about what method to go with and very scared to remove my 4 healthy tooth. Heard about relapse of tooth after the tooth extraction. Are there any other possible solution for my case?? I have attached my lateral and opg xrays of mine done before putting braces.Please suggest me the best way to have a good smile. Kindly respond as soon as possible.