A Comparison of Viscoelastic Properties of Three Root Canal Sealers

Objective: Handling of endodontic sealers is greatly dependent on their elasticity and flow ability. We compared the viscoelastic properties of three root canal sea- lers. Materials and Methods: AH Plus (Dentsply, De Trey, Konstanz, Germany), En- dofill (Dentsply Hero, Petrópolis, Rio de Janeiro, Brazil) and AH26 (Dentsply, De Trey, Konstanz, Germany) were mixed according to the manufacturers' instruc- tions. The resulted pastes were placed on the plate of a rheometer (MCR 300, An- ton-Paar, Graz, Austria). The experiments were performed at 25˚C and 37˚C. Vis- coelastic properties of the sealers including loss modulus (G"), storage modulus (G´) and complex viscosity (η*) were studied using dynamic oscillatory shear tests. The shear module versus frequency (from 0.01 to 100 S-1) curves were gained using frequency deformation sweep test. Three samples of each material were examined at each temperature. The mean of these three measurements were recorded. Results: The storage modulus of AH plus was higher than its loss modulus at two temperatures. Endofill exhibited a crossover region in which the storage modulus crosses the loss modulus in both temperatures. At 25ºC the loss modulus of AH26 was higher than the storage modulus (G">G). In contrast, at 37ºC Gwas greater than G(GG). Both shear modules of AH Plus and Endofill decreased as the temperature raised from 25ºC to 37ºC. On the contrary, the loss modulus and sto- Corresponding author: M. Pishvaei, Department of Resin and Additives, Institute for Color Science and Technol- ogy, Tehran, Iran mapishvaei2@yahoo.com Received: 22 November 2012 Accepted: 9 January 2013 rage modulus of AH26 increased at 37ºC. Conclusion: In both test temperatures, AH Plus behaved like viscoelastic solids and Endofill exhibited a gel-like viscoelastic behavior. AH26 at 25ºC behaved like liquids, while at 37ºC it was an elastic solid-like material.