Removal: If your bitten scar has existed for more than 3 months, it means that the bitten scar has completely "solidified" and the brown spots are deposited by dead pigment cells. Removing them is not easy. Unless the drugs used are corrosive, the brown spots will be corroded and the epidermis will grow again, but there will be bigger scars after failure. The quickest treatment is to use grinding. You can go to the hospital or the dentist to polish one with a grinder first.