An electronic device for locating the apex of a root canal within a tooth of a dental patient has a display screen on a display component to provide an image indicating when the apex of a root canal has been located. A free end of a first electrical lead is provided for placement within the root canal or in contact with an electrically conductive tool within the root canal. A free end of a second electrical lead is used to establishing a ground on a conductive portion of the dental patient such as a tissue surface within the mouth. The opposite ends of each of the leads is connected to the display component. Removeably attached to the display component is a lead carrier. The detachable lead carrier and the leads mounted thereon can be sterilized as a unit and then attached to the display component, which is bagged in a sterile barrier, for performing the apex locating procedure. The apex locator has one or more mounting structures for placing the display in a location adjacent the patients head, attached to adjacent instrumentation, or attached to the dental practitioner's hand or arm such that the display image is readily visible by the dental practitioner during the apex locating procedure.