Tensile Properties of Orthodontic Elastomeric Chains

Aim: Orthodontic elastomeric chains are a main component in orthodontic therapy employing labial or lingual appliances. The aim of this study was to investigate the tensile properties of orthodontic elastomeric chains with a test setup according to ISO 21606:2007. Material and Methods: Orthodontic elastomeric chains of eight manufacturers with and without an intermodular link were obtained from commercially-available stock, yielding 23 groups with ten specimens each. Samples were mounted in a universal testing machine and extended at a rate of 100 mm/min to four times the initial length and held for 5 seconds. After 5 seconds, the chain lengths were reduced to an extension of three times the initial length and held for 30 seconds before extension until failure. Forces at four times the test length (Fmax1), three times the initial length (Fmin) as well as force (Fmax2) and length (Lmax) at failure were recorded. Data were statistically analyzed by one-way analysis of variance using SPSS® 17. The level of significance was set at p = 0.05. Results: Statistical analysis revealed significant differences in Fmax1, Fmin, Fmax2 and Lmax among the various manufacturers. Fmax1 ranged between 9.1 N and 23.2 N, Fmin ranged between 1.5 N and 3.0 N, Fmax2 ranged between 15.7 N and 34.0 N, and Lmax ranged between 425% and 629% of the initial length. Conclusions: The tensile properties of different manufacturers of elastomeric orthodontic chains differ statistically significantly. Hence the amount of orthodontic force that is applied depends significantly on the type of elastomeric chains used in combination with labial or lingual appliances.