A cystostomy as a treatment option for larger cysts enables sparing of adjacent roots and nerves. Mucosa and bone are opened above the cyst. A window is cut along the bone opening, the actual cyst remains in the bone. This cavity is tamponaded to remain open and is thus formed to create an adjacent oral cavity bay. As the opening does no longer allow the cyst to grow, this bone cavity becomes ever smaller with the passing of time.