The Research And Property Analysis Of Domestic Elastomeric Ligators

Objectives:To compare two different brands of orthodontic elastomeric ligators with frictional resistance and tensile properties.To familiar with the properties of the elastomeric ligators, help othondontist apply the knowledge to different cases.Materials and Methods:Choose two brands of the elastomeric ligators:one is PT gray elastomeric ligator which is domestic brand, anther is 3M Unitek Alastik Force Products and Intraoral Elastics which is made in USA. We kept at room temperature and humidity, use Germany zwick universal testing machine to test the maximum static and sliding friction of combination of two liagting methods(0-like ligation and 8-like liagation) and in different time. Used with standard brackets and 0.019*0.025-inch stainless steel archwires.Also test the tensile properties of the two brands elastomeric ligators with Germany zwick universal testing machine in wet condition. Measure the extension with different scale of stretching forces. Then test the elastomeric ligators of their Breaking Force,the tensile length of the breaking force,the Maximum load,the tensile length of the maximum load. In wet condition, Measure the force of elastomeric liagators stretching to length of bracket of maxillary first premolar in different time。Calculate the stress-relaxation。Also, in wet conditions, measure the dimensions of the two brands elastomeric ligators, including the wall thickness,inside diameter,outside diameter. Measure the deformation of the elastomeric ligators。Results:0-like ligation, in 1 hour the PT and 3M elastomeric ligators the maximum static respectively are 8.23±0.62N,10.84±1.09N, the sliding friction respectively are 6.47±0.51N.9.29±1.22N; in 2 hour the PT and 3M elastomeric ligators the maximum static friction respectively are 6.87±1.02N,7.07±1.29N, the sliding friction respectively are 5.78±0.41N,5.43±1.47N; in 24 hour the PT and 3M elastomeric ligators the maximum static friction respectively are 5.68±0.89N,6.76±0.57N, the sliding friction respectively are4.41±0.26N,5.10±0.66N; in 48 hour the PT and 3M elastomeric ligators the maximum static friction respectively are 4.53±1.45N,4.43±0.21N, the sliding friction respectively are 3.76±1.23N,3.12±0.67N.8-like ligation, in 1 hour the PT and 3M elastomeric ligators the maximum static friction respectively are 10.40±2.27N,10.30±1.35N, the sliding friction respectively are 9.59±2.19N,9.02±1.67N; in 2 hour the PT and 3M elastomeric ligators the maximum static friction respectively are 7.76±0.80N,7.72±0.14N, the sliding friction respectively are 7.13±0.65N,6.67±0.18N; in 24 hour the PT and 3M elastomeric ligators the maximum static friction respectively are 6.19±0.49N,5.22±0.51N, the sliding friction respectively are5.30±0.53N,4.53±0.42N; in 48 hour the PT and 3M elastomeric ligators the maximum static friction respectively are 5.56±0.64N,5.22±1.36N, the sliding friction respectively are 3.74±0.64N,4.04±0.42N. Compare with different brands, results showed that lhour, the sliding friction of PT is smaller than 3M, statistically significant different (p<0.05,F> Fo.o5(1,4)=4.55).At the time of 24 hours in 8 like ligation, the maximum static friction of the two brands are statistically significant different (p<0.05,F> Fo.o5(1,4)=4.55)。PT elastomeric ligators, 0-like ligation group, comparing the friction in 24 hours with in 2 hours, it decayed significantly as time passed by,there are statistically significant different.In 8-like ligation group, also the maximum static and sliding friction decayed by the time, there are statistically significant different, p<0.01.3M elastomeric ligators,0-like ligation group, comparing the friction in 1 hours with in 2 hours, it decayed significantly as time passed by,there are statistically significant different.the same situation happened in the compareing the friction in 2 hours with 24 hours, and in 24 hours and 48hours.In the tensile test, in PT elastomeric ligator group, the Maximum load is 19.49±0.82N, the tensile length of the maximum load is 7.93±0.65mm, the breaking force is 17.46±1.14 N, the tensile length of the breaking force is17.46±1.14 N, in 3M elastomeric ligator group, the Maximum load is 19.33±1.68 N, the tensile length of the maximum load is 9.39±0.31mm, the breaking force is 18.47±2.18N, the tensile length of the breaking force is 9.85±0.32mm, the tensile length of the maximum load of the two brands of elastomeric ligators are statistically significant different。the tensile length of the maximum load of PT elastomeric ligator is smaller than 3M(F=20.765,p=0.002<0.01).Use the measuring microscope measure the new elastomeric ligators of two brands. There is no different between the new elastomeric ligators and the ligators in water 48 hours about the deformation. And at least the measuring microscope cannot distinguish the deformation.Conclusion:1. The two brands at first time there friction have significant different, but as the time passed by, there are no significant differences between two of them.2. The friction of the elastomeric ligators decayed significantly in two days.3. The different ligation methods impact the change of the friction.4. The tensile length of elastomeric ligators have linear relationship with the tensile stress.5. In this experiment, the stress-relaxation TP and 3M elastomeric ligators are respectively 84.46%和67.97%.6. In 48 hours, the deformation of the two brands of elastomeric ligators in pure water can't be detected by measuring microscope of which accuracy grade is 0.01mm.