Inclusion Criteria:  active pain in a mandibular molar first or/and the second molar prolonged response to cold testing absence of any periapical radiolucency on periapical radiographs vital coronal pulp on access opening able to give informed consent  Exclusion Criteria:  less than 18 years old history of serious medical problems used central nervous system depressants or any analgesic medication within the previous 6 hours pregnancy inability to give informed consent