The aim of this study was to compare the force relaxation between traditional latex elastics to different brands of non-latex elastics in a simulated saliva solution. The force relaxation of 6.35 mm (0.25 inch), 99 g (3.5 oz), non-colored latex elastics from Ormco Corp. and non-latex elastics from Phoenix Orthodontics, ClassOne Orthodontics, and Glenroe was tested. The elastics were stretched to 40 mm (1.57 inch) and the force produced by the elastics was then measured using a Mini 44 Instron machine.
Results: The latex elastics had an initial relaxation of 15 percent after 1 hour of incubation and maintained their reduced force after 24 hours of incubation. Non-latex elastics lost approximately 20 percent of their force after the first hour and continued to lose force after up to 24 hours of incubation resulting in as much as 48 percent force relaxation.
Conclusion: Latex elastics should be used whenever possible; however, when non-latex elastics are warranted, the clinician should take into account their greater initial forces, significant force relaxation, and variability among brands.