Objective To test the tensile properties of four kinds of orthodontic latex elastics commonly used in clinic. Methods Four kinds of orthodontic latex elastics with the same elastic parameter were chosen. The elastics were divided into 3/16, 1/4, 5/16 group, and 3/8 groups according to inner diameter. An electronic universal mechanical testing machine was used to test their specialized mechanical properties. The relation between load and the deformation of the four elastics within 0 mm to 60 mm strain range was determined, and deformation-load tables were established. Results Inner diameter and deformation value both influenced the load of the orthodontic latex elastics(P=0.000) significantly. The deformation-load curve approximated linear relationship in the range of 5 mm to 40 mm deformation, and the slopes were of no statistical significance. The load of different elastics with the same deformation was substantially different. The 1/4 and 3/8 groups showed no significant difference between the inner diameter elastics load and the corresponding standard value(P>0.05) under triple stretch length, whereas the 3/16 and 5/16 groups did(P>0.05). Conclusion The load of the orthodontic latex elastics varied with the inner diameters and deformation, indicating that elastics should be selected appropriately based on the value of the force required in clinics.
