The effect of static and dynamic testing on orthodontic latex and non-latex elastics

The purpose of this study was to test the force decay properties of different kinds of orthodontic elastics after subjecting them to static and cyclic testing. Latex and non-latex elastics obtained from GAC, American Orthodontics and Ortho-Organizers were used in a sample size of 10 elastics per group. Static testing involved stretching the elastics three times the internal diameter, while in cyclic testing, the elastics were stretched up to 50 mm to simulate maximum mouth opening. Elastic forces generated were measured using the Instron testing machine and recorded in grams. Elastics on average lose 10% and 12% as a result of static test and 30% and 35% as result of cyclic test for latex and non-latex brands respectively, and most of the force loss occurs during the first half hour and after the first 10 cycles. This difference in force loss between latex and non-latex elastics could be due to the different structure and composition of the polymer involved. There are no significant differences between different groups of latex elastics in terms of force loss or even between the different groups of the non-latex elastics under static testing, however, under cycling testing differences between the groups were detected. Forces generated by the elastics are different from the manufacturers’ labeled forces.