A 39-year-old man has had intermittent pain on the lower right side for 5 days and cannot say which tooth is responsible. The results of the clinical tests on his lower right premolar and molars are shown in the image. The periapical radiograph shows a deep distal composite on the first molar with a widened periodontal ligament space at the mesial root, and no other abnormality. What is the most likely pulpal and periapical diagnosis?