A 23-year-old woman complains of carious cavity present in the 27 tooth, where food particles are retained. Objectively: there is a deep carious cavity on the masticatory surface of the 27 tooth filled with dense dark-brown dentin. Probing of the cavity floor and walls is painless, thermometry and percussion are painless. Electric pulp test - 10 microamperes. X-ray reveals no pathological changes. Make the diagnosis: