(This phrase acts like a noun. It is the direct object of the verb stopped. This phrase is a gerund phrase.) I stopped believing in Santa Claus when my mother took me to see him in a department store, and he asked for my autograph. (This phrase acts like a noun. It is the subject of the adverbial clause when my mother took me to see him in a department store.) I stopped believing in Santa Claus when my mother took me to see him in a department store, and he asked for my autograph.  It is the object of the preposition for.)
Ive googled 'white in extraction site'(!) and had some conflicting info: 'The white material is the blood clot; your rinsing has merely washed away the red blood cells and left the clotted fibrin material, which is white. This is normal, and is of no concern'. The second: 'White color in the extraction cavity...
If in doubt or if bleeding goes on for more than a few hours, contact your dentist. To keep the clot undisturbed, aftercare in the first 24 hours after tooth extraction should include: What you do in the first 24 hours are very important in terms of fast healing. Avoid hot drinks, and take small sips when drinking fluids. Do not use a straw (the resultant suction pressure can dislodge a clot).