The effect of repeated stretching on the force decay and compliance of vulcanized cis-polyisoprene orthodontic elastics.

Compliance measurements, used in the past to measure the viscoelastic properties of dental impression materials, were used to assess these properties in vulcanized cis-polyisoprene orthodontic elastics, and the results were compared with traditional force decay measurements. Both methods were also used to evaluate the effect of repeated stretching on these elastics. Compliance measurements successfully characterized the viscoelastic behavior of the elastics, and the results agreed with force decay measurements. Repeated stretching significantly reduced the force and the compliance of the elastics. There was no statistical difference in the force or compliance measurements after the elastics were stretched more than 200 times. Stretching for 1000 cycles of 400% extension reduced elastic force by approximately 12%.