Hello there and welcome to HCM,
Your extraction of wisdom teeth is no where related to the bruise
on the arm.As you have described purple reddish bruise i can suspect formation of hematoma
on the arm due to long placement of scalp
vein or misplaced scalp vein. i suggest you to visit a physician and get it confirmed. If it is hematoma it will resolve in few days with proper medication . dont worry but see a doctor before the condition gets worse. get well soon and take care.