Objectives: Elastomeric chains are used extensively to effect orthodontic tooth movement. Many studies have assessed the properties of these materials but there is limited data on the effects of storage media on their tensile properties. Methods: Tensile studies were performed on American Orthodontics long span open loop, short span open loop and closed loop elastomeric chain. The specimens were tested after storage in water, 0.9% saline and Ringer's lactate for 48 h at RT and 37°C. The chains were suspended with 3 loops between hooks held in the jaws of a Satec T5000 tensometer and were tensile tested at 5 mm/min to a maximum load of 450 g. After load release and 30 s relaxation, the chains were re-loaded to 450 g. The force (P) vs displacement (d) behavior was continuously recorded. All tests were performed on at least 4 sets of specimens and data were analyzed by ANOVA and post-hoc Scheffé tests. Results: The P vs d behavior varied for the 3 types of chain and the displacement to achieve a given load increased from closed loop to open short to open long span chains (p<0.05). The tensile behavior was affected by the storage medium, with chains soaked in saline exhibiting lower ductility than those in water and Ringer's lactate. No difference (p>0.05) in P vs d was found with chains stored at 37° compared to RT but pre-stretching the chains resulted in a more linear force-displacement behavior. Conclusions: The tensile behavior of elastomeric chains is affected by the media to which they are exposed and the effects are greater with long span chains. Pre-stretching of chains provides more predictable force vs displacement behavior.

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