We report two extremely rare cases of wisdom tooth-germ infection in the mandible of young individuals. The first case was a 14-year-old male who presented with drainage from the left cheek at the Department of Oral Surgery in the National Hospital Organization Kumamoto Medical Center. After treatment with malar incision and drainage at another hospital, the patient was referred to our department because of an external dental fistula. Radiographic examination showed hypoplasia of the lower left wisdom tooth-germ. An extraction of the tooth-germ was performed under local anesthesia. The external dental fistula healed within 5 months of the surgery. The second case was a 12-year-old female who presented with trismus and swelling in the lower left mandibular region. Radiographic examination showed an increase in bone density, periosteal reaction of the left mandibular bone and destruction of the buccal cortical bone of the lower left wisdom tooth-germ. After treatment with antibiotics, the tooth-germ was surgically enucleated under general anesthesia. No signs of recurrence were observed at the 14-month postoperative follow-up. Although there are few reports on wisdom tooth-germ as a cause of chronic suppurative inflammation because external dental fistula and mandibular osteomyelitis are extremely rare, the possibility of an infected wisdom tooth-germ causing chronic suppurative inflammation should be considered.