A third-degree burn is usually permanent, as it burns through the skin and affects the nerves and fat that sit below. This leaves a permanent scar. However, it may not be painful if the nerves are not affected or if they are completely killed. Although they are usually not considered permanent, second-degree burns can leave a mark or scar on the skin long after the pain has subsided. Seek medical help for any type of second or third-degree burn.