A Nonlinear Viscoelastic Model to DescribePeriodontal Ligament Behavior

The periodontal ligament (PDL) is a soft biological tissue which shows a strongly nonlinear and timedependent mechanical behavior. Recent experiments on rabbit PDL revealed that the rate of stress relaxation is straindependent. This nonlinear behavior of PDL cannot be described well by the separable quasi linear viscoelasticitytheory which is usually used in tissue biomechanics. Therefore, PDL requires a more general description whichconsiders this nonlinearity and time dependency. The purpose of this study was to model strain dependent stressrelaxation behavior of PDL using modified superposition method. It is shown herein that modified superpositionmethod describes viscoelastic nonlinearties well and shows a good compatibility with available experimental PDL data.Hence, the modified superposition model is suggested to describe periodontal ligament data, because it can suitablydemonstrate both elastic nonlinearity and strain-dependent stress relaxation behavior of PDL.

Keywords:

periodontal ligament , viscoelasticity , modified superposition method , stress relaxation