The Stress Relaxation Of Orthodontic Elastomeric Ligatures, Elastomeric Chain And Nickel Titanium Coil Springs

Objective: By way of measure the stress of elastomenc ligatures, elastomenc chain and nickel titanium coil springs periodically after three different loads were load on, to evaluate the stress relaxation of them. And compare the stress relaxation of the three different loads, as well as to compare the elastomenc ligatures, elastomenc chain and nickel titanium coil springs. By this way, it can guide the clinical operation of orthodontics.Methods: The randomly selection elastomenc ligatures, elastomenc chain and nickel titanium coil springs each nine, each kind of goods randomly divide into three groups, each group of three, every group goods distinction load 100 gram, 150 gram and 200 grams. In the experiment measure the stress of elastomenc ligatures, elastomenc chain and the nickel titanium coil springs under different load regularly. Carries on the comparison to the different goods under same load and makes the statistical analysis, carries on the comparison to the homogeneous goods under different load rate of change and makes the statistical analysis.Results: The research discovered elastomenc ligatures and elastomenc chain are biggest in the experimental initial 48 hour internal stress weaken, after load 48 hours remaining stress for about initial stress 80%. After 48 hours their stress relaxation speed reduces gradually, to 32nd day remaining stress for initial stress 70% - 80%. The nickel titanium coil springs relaxe in most first week the circumferentialstress obviously, reduce gradually to about initial stress 90%, afterwards the stress maintenance constant no longer weakens.Elastomeric ligatures, elastomeric chain and the nickel titanium coil springs distinction load 100 grams, after 32 days slow changes, elastomeric ligatures remaining stress is mailer than nickel titanium coil springs, elastomeric chain and the nickel titamum coil springs remaining stress does not have statistics difference.Elastomeric ligatures, elastomeric chain and the nickel titanium coil springs distinction load 150 grams, after 32 days slow changes, elastomeric chain remaining stress is smaller than the nickel titanium coil springs, elastomeric ligatures and the nickel titamum coil springs remaining stress does not have statistics difference.Elastomeric ligatures, elastomeric chain and the nickel titanium coil springs distinction load 200 grams, after 32 days slow changes, elastomeric chain remaining stress is smaller than the nickel titanium coil springs, elastomeric ligatures and the nickel titamum coil springs remaining stress does not have statistics difference.Elastomeric ligatures under the different load the 32 days, the stress relaxation rate of change is same.Elastomeric chain under the different load the 32 days, the stress relaxation rate of change is different, initially when the load 100 grams time stresses weaken slowly.The nickel titanium coil springs under the different load the 32 days, the stress relaxation rate of change is same.Conclusion: The nickel titanium coil springs elasticity surpasses elastomeric ligatures (active ligatures);the stress of elastomeric ligatures and elastomeric chain weakens quickly in the first 48 hours. Afterwards is stable;The small the load is, the slightly the elastomeric chain stress weakens.