Marsupialization is one of the best therapies for dentigerous cyst, especially for the possibility of preservation of the involved permanent tooth. Many factors, for example, the age of the patient, the region of the cyst and the situation of the involved tooth itself, had made it difficult to ensure the prognosis of the displaced teeth on their spontaneous eruption following the surgery. Fifteen dentigerous cysts in the lower premolar region in twelve children aged eight to thirteen were marsupialized, and the inclination of adjacent teeth was prevented by using an acrylic denture type obturator. We observed the reactions of the involved teeth and the decrease in size of the cysts. The results were as follows;
1. In the nine central dentigerous cysts which surround the entire crown of the involved teeth, all of the teeth, even horizontal tilted teeth or matured teeth, erupted in almost normal positions with marsupialization and retention of the eruption spaces.
2. In the six lateral dentigerous cysts which form at one side of the involved teeth, the teeth didn't have enough capacities to improve their tilted dental axes with marsupialization. Especially on the cases involving matured teeth, they couldn't erupt enough without orthodontic intervention.
3. The bony regeneration was comparatively rapidly achieved with marsupialization. Every cyst remained only a small cavity in 3 to 6 months after surgery. The cavity also disappeared about one or one and half years later when the involved tooth completed eruption
