A patient presents with a partially erupted mandibular third molar (tooth #17). Which complication is most likely to develop in the future if left untreated?

Pericoronitis — inflammation of the soft tissue (operculum) surrounding a partially erupted tooth — is the most common and predictable complication of a partially erupted mandibular third molar. The operculum creates a pocket that traps food debris and bacteria, leading to recurrent acute episodes of pain, swelling, and trismus. Pericoronitis can progress to spreading infections if untreated. While caries on the adjacent second molar and dentigerous cyst formation are also recognized complications, pericoronitis is the most immediately likely complication and the most common reason patients seek treatment for impacted third molars.