Latex and Non-latex Orthodontic Elastic Force Loss from Cyclic Temperatures

Objectives: To compare the force loss of latex elastics (LE) and non-latex elastics (NLE) while cycled between water baths of varying temperatures.

Methods: Medium 6.35mm, 3.5oz LE (Ormco Corp.) and NLE (ClassOne Orthodontics and Phoenix) (n=20 per test) were stretched to 40mm on jigs placed in distilled water. The elastics were either incubated at 37⁰C for 4min or cycled between water baths of 5⁰C and 37⁰C, 22⁰C and 37⁰C, 5⁰C and 50⁰C, or 37⁰C and 50⁰C 20 times spending 3s in each water bath and 3s transferring between water baths using an automated system. The original force of the elastics was determined by measuring the force of new elastics that had not been previously incubated or stretched. Force was measured using a Mini 44 Instron (Instron).

Results: Two sample T-test showed statistically significant differences (P<0.05) among brands when the temperature of a water bath was 50⁰C, and within a brand when all temperature cycles were compared to the control of 37⁰C except for LE when cycled between 5⁰C and 37⁰C and all elastics when cycled between 21⁰C and 37⁰C. NLE maintained only 70-75% of their original force after being cycled between 37⁰C and 50⁰C. LE maintained 80% of their original force when cycled between 37⁰C and 50⁰C and only 73% of their original force when cycled between 5⁰C and 50⁰C.

Conclusion: All elastics had a trend of increased force loss with higher temperatures except for LE which had the greatest force loss when cycled between 5⁰C and 37⁰C. This could have clinical relevance for patients that drink hot liquids in the morning after putting on their orthodontic elastics or those who eat while wearing them.