In-vitro Evaluation of Force Decay in Thermoplastic and Thermoset Elastomeric Chains of the Same Brand

Objectives: To evaluate and compare the force decay of short-link transparent thermoplastic and thermoset elastomeric chains from American Orthodontics. Materials and Methods: Thirty-three-link chain segments (with one link at each end for easy handling) were assigned to two groups: 15 thermoplastic chains and 15 thermoset chains. Initial force values were measured using an MTS Universal Testing Machine. Each group was then stretched to 20 mm (double its original length) and immersed in containers with artificial saliva at 37°C. The chains were removed at 24 hours, 7, 14 and 21 days to measure force decay and analyze statistical results. Results: Thermoplastic chains exhibited a 9.46% greater force decay than thermoset chains at the end of the 21-day study. The greatest force loss in both groups occurred within the first 24 hours. Conclusion: Thermoset elastomeric chains maintain more stable and consistent force values compared to thermoplastic chains, indicating their greater effectiveness in orthodontic treatments. A clear distinction should be made between these two types of chains, as each performs differently in terms of force decay.