External root resorption.

Root resorption is a pathological process initiated by specific clastic cells which remove the organic and mineral components of dental hard tissues. Clastic cell activity in teeth is associated with a number of factors which include biomechanical forces, mechanical, surgical and chemical trauma, endodontic micro-oragnisms and their toxins, developmental defects, neoplasia, and hormonal disturbances. The therapeutic measures which can regulate clastic activity include endodontic treatment, the use of specific anticlastic agents such as Ledermix paste, non-specific necrobiotic agents such as calcium hydroxide and trichloracetic acid, surgery or root surface conditioners. Accurate diagnosis is essential to the correct application of therapy. While some resorptions are self-limiting, others such as inflammatory root resorption require active and prompt endodontic preparation and medication to allow the control of clastic activity. One treatment regimen of invasive cervical and related conditions involves careful and accurate application of a chemical cauterizing agent, trichloracetic acid, followed by curettage and restoration.