A 43-year-old man complains of an intense unbearable pain in the area of the upper jaw; his general condition has been disturbed for 5 days. Objectively, his face is asymmetrical due to a swelling of the buccal and zygomatic regions. In the oral cavity, tooth 26 is destroyed, mucosa of the alveolar bone is hyperemic and edematous; there is a cuff-shaped thickening of the alveolar bone in the area of teeth 25, 26, 27; teeth 25, 26, and 27 exhibit I degree mobility. Make the provisional diagnosis: