Abstract
When jaw cysts are infected, polyunsaturated fatty acids, especially C 20: 4, constitution ratio decreases in the fluid of the cysts. The author considered that this change was because of the formation of lipoperoxides and prostaglandins from those fatty acids. The relation between the concentration of lipoperoxides and the infection of the cysts was studied. As a result, the infected cyst fluids showed high TBA value; when the infection was removed by irrigations in the cyst cavities, the value decreased and the cysts diminished in size. According to the author's investigations, it can be said that jaw cysts enlarge with the increase of lipoperoxides by the infection or the inflammation of jaw cysts.