A 7-year-old child is in a grave condition, teeth of the upper left jaw are painful, body temperature is 39,3°C. The child is pale, adynamic; the face is asymmetrical due to infiltration in the upper left jaw. The 64 tooth is filled, painful on percussion. The 63 and 65 teeth are intact, painful on percussion. The I degree of tooth mobility is observed; pus is being discharged from under the marginal gingiva of the 64 tooth. The alveolar process is deformed at its vestibular and palatine surfaces. Make the provisional diagnosis: