An 8-year-old child complains about permanent dull pain in the 46 tooth that is getting stronger during cutting. The pain appeared 1 day ago. Previously there has been pain induced by cold stimuli. Objectively: there is a deep carious cavity on the masticatory surface of the 46 tooth, tooth cavity is closed, probing and temperature stimuli cause no pain reaction. Percussion is painful, a slight mobility is present. Gum around the 46 tooth is hyperemic, edematic, palpatory painful. X-ray picture shows no changes near the apex of undeveloped roots. What is your provisional diagnosis?