If the pulpal necrosis is asymptomatic it may go unnoticed by the patient and so a diagnosis may be missed without the use of special tests. To determine if pulp necrosis is present a dentist may take radiographic images (X-rays) and sensitivity testing e.g. hot or cold stimuli (using warm gutta percha or ethyl chloride); or they may use an electric pulp tester. Vitality of a tooth, which refers to blood supply to a tooth, may be assessed using doppler flowmetry. Sequelae of a necrotic pulp include acute apical periodontitis, dental abscess, or radicular cyst and discolouration of the tooth.