A 25-year-old man complains of shortterm pain in the tooth on the lower right jaw during eating sweet, hot, and cold food. Objectively: in the 36 tooth on the distal surface there is a carious cavity non-communicating with the dental cavity, dentin is softened. Probing of the cavity floor is painful, percussion is painless. Electric pulp test is 16 microamperes. Make the final diagnosis: