Document Type : Original Article


1 Assistant Professor, Orthodontics Department, Faculty of Dentistry, Ahvaz Jundishapur of Medical Sciences, Ahvaz, Iran.

2 Orthodontist, Tehran, Iran.

3 Dentist, Tehran, Iran.



Background and aim: Elastomeric chains are crucial to orthodontics. Hence, their efficacy and force decay should be investigated. In this regard, chain morphologies and stretching extents are not assessed adequately. Therefore, we aimed to assess these parameters.

Materials and Methods: Two-hundred-and-seventy elastics from 3 brands [Ortho Technology (OT), American Orthodontics (AO), G&H, 10 specimens×27 subgroups] were stretched for 40%, 60%, and 100% elongations. Their initial forces were measured. After 4 weeks of incubation in artificial saliva, their residual forces were measured. Forces and force decays were compared across brands, morphologies, and stretching extents (α=0.001).

Results: Forces degraded significantly over time (repeated-measures ANOVA, P<0.001). There were significant differences among levels of all parameters, in terms of the initial forces, residual forces, and force degradation (3-way ANOVA, P<0.001). Most of Tukey post hoc tests were significant (P<0.001). The longer the stretching extent, the higher the force waste (partial correlation coefficient, r=0.885, P< 0.001).

Conclusion: The initial force was improved when using the OT brand, utilizing closed chains, and by elongating the elastic for 100%. Force loss would be minimized using the G&H brand, open elastics, and 40% elongations. Using OT, closed elastics, and 100% elongations would cause the highest residual forces after a month. However, the initial forces provided by the 100% elongations would not be much healthy. Force loss would be increased while using OT brand, using closed elastics, and with 100% elongations. The lowest residual forces were seen in the AO brand, long elastics, and those stretched for 40%.


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