The growth and enlargement of jaw cysts are associated with raised intracystic pressure and bone resorption surrounding the cysts.The major bone-resorbing cells are the osteoclasts.They are acting under the influence of local bone-resorbing factors: prostaglandins,proteinases and cytokines.It was found that positive pressure enhanced the expression of IL-1αmRNA and protein in epithelial cells of odontogenic keratocyst,and increased the secretion of matrix metalloproteinase and PGE2 in a co-culture of odontogenic keratocyst fibroblasts and epithelial cells.However,the signal intensities for IL-1α mRNA and protein in the epithelium were significantly decreased after marsupialization which relived intracystic pressure.Experimental study indicated that intermittent negative pressure could promote osteogenesis in human bone marrow-derived stroma cells(BMSCs) in vitro.We propose a hypothesis that bone formation around the cyst of the jaws would be stimulated by intracystic negative pressure. The growth and enlargement of jaw cysts are associated with raised intracystic pressure and bone resorption surrounding the cysts. The major bone-resorbing cells are the osteoclasts. They are acting under the influence of local bone-resorbing factors: prostaglandins, proteinases and cytokines. was found that positive pressure enhanced the expression of IL-1α mRNA and protein in epithelial cells of odontogenic keratocyst, and increased the secretion of matrix metalloproteinase and PGE2 in a co-culture of odontogenic keratocyst fibroblasts and epithelial cells. Host, the signal intensities for IL -1α mRNA and protein in the epithelium were significantly decreased after marsupialization which relived intracystic pressure. Experimental study that intermittent negative could could promote osteogenesis in human bone marrow-derived stroma cells (BMSCs) in vitro. We propose a hypothesis that bone formation around the cyst of the jaws would be stimulated by intracystic negative pressur e.