ABSTRACT
Biomechanical reactions of tooth movement are the combination of bone formation and resorption, in which many paracrine factors are involved. The sex hormone is one of the paracrine factors and the sex hormonal level of an adult female varies according to the body condition, e.g. mensturation, pregnancy, postmenopause, etc. Although the exact mechanism is not clarified yet, estrogen and progesterone are known to regulate the function of osteoblast. Again osteoblast is reported to affect the function of osteoclast. The purpose of this study is to determine the influence of the female sex hormone, estrogen and progesterone, on the cell proliferation and activity of HOS and ROS17/2.8 cell line. The observed results were as follows. 1. Estrogen inhibited HOS cell proliferation and promoted ROS17/2.8 cell proliferation. 2. Estrogen increased the activity of alkaline phosphatase of HOS cell and reduced the activity of alkaline phosphatase of ROS17/2.8 cell. 3. Progesterone inhibited the proliferation of HOS and ROS17/2.8 cell, but had no influence on the activity of alkaline phosphatase. 4. Estrogen and progeterone did not have any particular effects on the activity of super oxide, nitric oxide and gelatinase of HOS and ROS17/2.8 cell.
Subject(s)
Adult , Female , Humans , Pregnancy , Alkaline Phosphatase , Cell Line , Cell Proliferation , Estrogens , Gelatinases , Nitric Oxide , Osteoblasts , Osteoclasts , Osteogenesis , Postmenopause , Progesterone , Tooth Movement TechniquesABSTRACT
Nitinol wires are now widely used in the orthodontic field because of their unique shape memory effect and superelasticity. But sometimes Nitinol wires are deformed in clinical use. Fatigue load is possible cause of Nitinol deformation. To determine the effect of fatigue load to the mechanical properties of Nitinol, various fatigue cycle(1X10(4), 2X10(4), 3X10(4), 4X10(4), 5X10(4), 1X10(5)) were applied to 0.017 X 0.025 inch Nitinol. The results obtained were as follows; 1. Applied load increased as fatigue cycle increased in three point bending test. 2. Maximum tensile strength and elongation decreased as fatigue cycle increased. 3. In SEM, brittle fracture pattern was increased when fatigue cycle increased.