Generally speaking, patients with mouth ulcers can be cured if the cause is identified and treated promptly. It can be caused by fire, but this is only one of the possibilities, as well as infection, malnutrition and trauma. Therefore, if you have an ulcer at the corner of your mouth, it is important to have it examined further and not just assume that it is a fire and not undergo the standard treatment to avoid delaying the condition and causing serious consequences due to negligence.