<P> Denailing is the extraction of the nails from the fingers and / or toes, either as a medical procedure to treat severe nail infections, or as a method of torture . The United Nations Istanbul Protocol describes nail removal and the insertion of objects such as wire under the nail as forms of torture . Removed nails are capable of growing back normally over several months if the nail matrix is left intact through surgical extraction . However, if the matrix is damaged by trauma, it can result in an overgrowth of tissue from the proximal nail fold, resulting in the formation of pterygium . Particularly, if the nail matrix is burnt by a heated instrument, subsequent growth may produce nails which are striped, thin, or broken into longitudinal segments . </P> <P> Medieval sources described the denailing interrogation process as conducted by laying the prisoner on a tabletop--securing the hands by chains around the wrists and the bare feet by chains around the ankles--and using a metal forceps or pliers--often heated red - hot--to individually grasp each nail in turn and slowly pry it from the nail bed before tearing it off the finger or toe . A more painful variant used in medieval Spain was performed by introducing a sharp wedge of wood or metal between the flesh and each nail and slowly hammering the wedge under the nail until it was torn free . </P>

If you pull a nail out does it grow back