Dented scars 20 years can generally be repaired, but the effect of repair varies from person to person, and commonly used repair methods include local injection treatment, physical therapy, surgical treatment, and so on. 1. Local injection treatment: collagen, hyaluronic acid and other substances can be injected locally into the concave scars, so that the concave scars can be raised, and the symptoms can be improved from the appearance. 2. Physical therapy: For those who have shallow scars, laser therapy is mainly adopted to use the high energy released by the laser to act on the localized scars, stimulate the regeneration of dermal collagen, and also break down the local pigmentation particles, which will help the recovery of the depressed scars. 3. Surgery: For more serious concave scars, lipofilling can be used to treat the scars, which generally involves taking autologous fat and filling it into the concave scars locally through surgery to improve the symptoms of concave scars. It is recommended that patients go to a regular hospital, follow the doctor’s instructions to choose the appropriate treatment, and if there is any discomfort during the treatment period, feedback to the treating doctor in a timely manner.