A dentigerous cyst involving the jaw is mainly developmental in origin. An inflammatory dentigerous cyst, frequently found in young patients, develops as a result of the intra-follicular spread of periapical inflammation from the overlying primary tooth. This case report involves a large inflammatory dentigerous cyst associated with right mandibular tooth displacement in an eight-year-old boy. Large dentigerous cysts that displace permanent teeth may require primary marsupialization in order to provide favorable outcomes and permit eruption of the permanent teeth.