<prompt> A cold test best localizesPain of pulpal origin.Periodontal pain.Pulp necrosis.Referred pain.  <response>: Hyperalgesia is manifested in endodontic pain patients when noxious stimuli e.g., refrigerant sprays or carbon dioxide snow used in the cold test produce much more pain than they would in teeth with normal pulp tissues. Spontaneous pain involves episodes of pain that seem to be unprovoked. All these changes can be partly Explained by sensitization of peripheral nerve endings in the pulp.Cohens Pathway of the Pulp ed:11th Pg551 