Now a days absorbable silk sutures are places that gets knocked out of the mouth gradually as the healing process goes on but it usually takes a week time for normal healing and it your case it has not even completed 4 days. So, I would recommend you to inform this to your dentist. Getting your healing site exposed can be an open invitation for bacterial to grow. Also maintain a good oral hygiene by doing warm saline gargles everytime you have meals. For more info visit the link...http://www.identalhub.com/article_do's-and-don'ts-after-tooth-extraction-153.aspx