An 18yr old male patient reported with chief complaint of pain and swelling in the right lower jaw and mild difficulty in opening mouth since one week. A general examination revealed fever and increased pulse rate.

Intra-oral examination showed signs of inflammation around the gingiva of partially impacted third molar tender on palpation with opposing tooth impinging. The most likely diagnosis is
Necrotising ulcerative gingivitis Localised aggressive periodontitis Acute herpetic gingivostomatitis Pericoronitis