A 30-year-old patient complains of a toothache caused by hot and cold stimuli. The pain irradiates to the ear and temple. Previously this tooth presented with spontaneous nocturnal toothache. Objectively: on the occlusal surface of the 37 tooth there is a deep carious cavity communicating at one point with the tooth cavity. Probing at the communication point, as well as cold stimulus, causes acute pain. The pain persists for a long time. Electric pulp test result is 55 microamperes. What is the most likely diagnosis?