Abstract :
Objective: To evaluate the residual force of direct-design elastomeric chains (open and closed) different Pre-stretching percentages. Materials and Methods: An in-vitro experiment was conducted using open (G-I) and closed (G-II) direct-design elastomeric chains 50%, 75%, and 100% prestretched and tested at measured across eight time intervals F0 (initial), F1 (1h), F2 (1d), F3 (2d), F4 (3d), F5 (7d), F6 (14d), and F7 (21d) using a digital force gauge at 37°C in artificial saliva.Results: All elastomeric chains exhibited significant force decay in the first 24h, which was followed by a slower, progressive decrease. Closed chains retained significantly higher residual force than open chains across all prestretched levels. Prestretching influenced early forces but had little long-term effect. At 21 days, residual forces (~0.5–0.9 N) were within the optimal orthodontic range.Conclusion: Closed-chain designs are preferable for sustained force. Elastomeric chains should be replaced approximately every 2 weeks to maintain optimal force delivery.
Keyword :
Elastomeric chains, Prestretch, Residual force.