The dentigerous cysts are the common cause that inhibits the eruption of the teeth. Large dentigerous cysts can cause pathological fractures in mandible. Temporary or permanent inferior alveolar and lingual nerve damage can occur associated with deeply impacted third molar surgery. We treated the dentigerous cyst arised from deeply impacted mandibular third molar with orthodontic extraction combined with the marsupialization therapy. This orthodontic-surgical procedure reduced the risk of nerve damage and pathological fracture of the mandible.