Surface resorption of the roots is relatively common. It starts when the organic precement layer is damaged and the cells of the PDL gain contact with the mineralized dental tissue. Resorption is done by multinuclear cells. Trauma is certainly one cause for surface resorption, but the reason may in many cases remain unclear. However, in the absence of continuing stimulation by bacteria, e.g., surface resorption stops and healing/repair will occur by the formation of cementoid tissue, protecting the exposed dentine. Surface resorption is not visible in the radiographs.