A friend is anxious because a child’s radiograph accidentally revealed a cyst in the jawbone with an unerupted tooth inside the cyst. The cyst required surgery, and the surgery might require the extraction of the tooth affected by the cyst. My friend thought that the tooth was very important and it would be a pity to pull it out. Indeed, the result of missing teeth not only affects chewing and misalignment of teeth, but may also affect the jaw development of children. How can a jaw cyst be removed and the teeth affected by the cyst be preserved? Open window decompression is an alternative treatment option. In layman’s terms, open window decompression is a procedure that creates an opening in the cyst to allow fluid to flow out of the cyst and reduce the pressure in the cavity. Since the cyst is enclosed in the jawbone, the pressure inside the cystic cavity gradually increases as the cystic fluid gradually increases. Under the pressure of the cyst, the surrounding jawbone slowly absorbs and the cyst gradually becomes larger. By opening and decompression surgery, the cyst wall is opened to allow the pressure inside and outside the cyst to be balanced, the jawbone tissue is slowly renewed, and the cyst gradually shrinks. Therefore, the purpose of open window decompression surgery is to reduce the cystic cavity, restore the shape of the jaw bone, and maximize the protection of the morphology and function of the jaw bone. Generally, the volume of most cysts in the jaw can be reduced by more than 50% through open window decompression in 6-18 months. In addition, some structures such as alveolar nerve and maxillary sinus, which are pushed and destroyed by the cyst, can also be repaired. Surprisingly, the teeth displaced by the cysts can gradually erupt with the reduction of the cysts and the growth of the jawbone, and even return to their normal position. Of course, the help and cooperation of an orthodontist is often needed to ensure that the teeth can return to their normal position. Open reduction surgery to preserve the teeth of children and adolescents with cysts has been reported in many domestic and international articles, especially for huge jaw cysts, with positive results. We reviewed dozens of patients in our hospital in recent years and also confirmed that open window decompression has a good effect on the preservation of teeth with jaw cysts in children and adolescents. It should be noted that not all cysts are suitable for open window decompression surgery. Although open window decompression has many advantages, it also has many inconveniences, such as the need for patients to wear a plug device (a device to prevent the healing of the open window) for a long period of time (usually 6-18 months); regular follow-up (usually once every 3-6 months); the need for stage II surgery to scrape out the reduced cyst if the cyst does not disappear completely after open window decompression; the inability of open window decompression to avoid the recurrence of cysts (mainly keratotic cysts, also known as keratosis cysts) from recurring. If the patient does not cooperate well, the effect of open decompression can be compromised.