The dentigerous cyst is defined as a cyst that originates by the separation of the follicle from around the crown of an unerupted tooth. This is the most common type of developmental odontogenic cyst, making up about 20% of all epithelium-lined cysts of the jaws. Large dentigerous cysts are uncommon, but some cases are large cysts. The usual treatment for a dentigerous cyst is careful enucleation of the cyst together with removal of the unerupted tooth. Large dentigerous cysts also may be treated by decompression. This permits decompression of the cyst, with a resulting reduction in the size of the bone defect. The cyst can then be enucleated at a later date with a less extensive surgical procedure and important structures such as teeth and the inferior alveolar nerve can be preserved. These cases are large dentigerous cysts treated by decompression. Less extensive surgical procedures were used and some teeth were preserved.