Final answer:
The probable diagnosis for the patient's symptoms is suppurative apical periodontitis, which is characterized by inflammation and infection of the tooth root's periodontal tissues. Treatment typically involves root canal therapy and the placement of an artificial crown.
Step-by-step explanation:
The probable diagnosis for a patient with a swelling associated with a tender tooth upon percussion, widening of the periodontal ligament space, and a negative response to electric pulp test is E. suppurative apical periodontitis. Suppurative apical periodontitis is an inflammation of the periodontal tissues caused by an infection in the tooth root, resulting in swelling, pain, and radiographic changes. In this condition, bacteria penetrate the tooth pulp, leading to inflammation and pus formation.
Suppurative apical periodontitis can be treated with root canal therapy to disinfect and remove the infected pulp, followed by the placement of an artificial crown to restore the tooth's function.