A patient complains of dull ache in the 16 tooth, which occurs during eating cold food. Anamnesis: the tooth had been filled due to deep caries, the filling was lost 1 year ago. Objectively: a deep carious cavity that does not penetrate the tooth cavity is present; percussion is painless, probing is painful along the whole floor of the carious cavity. Electric pulp test - 50 microamperes. Thermodiagnosis is painful. Make the diagnosis: