A 47-year-old patient complains about permanent pain in the 27 tooth that is getting worse when biting down on food. Objectively: the patient's face is symmetric, skin is of normal colouring, the mouth can be fully opened, mucous membrane of the alveolar process is edematic and hyperemic at a level of the 27 tooth. The 27 tooth has a deep carious cavity interconnecting with pulp chamber. Percussion of the 27 tooth causes acute pain. What is the most likely diagnosis?