Force degradation in elastomeric chains.

Elastomeric chains are a frequent choice for delivering forces required to close spaces orthodontically. Unfortunately, these forces degrade over time. Open and closed chains from six orthodontic suppliers were evaluated over time. For both types and for all suppliers, the greatest loss of force occurred within the first hour. During the next 2 to 4 days, forces delivered continued to fall but at a slower rate. Beyond that time, in general, forces delivered remain nearly constant but at a level lower than originally available. The amount of the force delivered at 28 days ranged from 85% to 30% of that available at the time of placement. At 28 days, gray chains from all suppliers delivered forces greater than 100 g.