An 18-year-old young man complains of a cavity in 27 and pain when eating solid food. He has a history of severe pain in 27 one year ago; he requested no medical help at the time. Objectively on the masticatory surface of 27 there is a deep carious cavity that communicates with the pulp chamber. The cavity is nearly completely filled with overgrown granulation tissue. Probing of the granulations leads to mild pain and bleeding. Percussion is painless. EPT is 45 microamperes. Make the diagnosis: