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KMID : 0362320110360050377
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Journal of Korean Academy of Operative Dentistry
2011 Volume.36 No. 5 p.377 ~ p.384
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Rheological characterization of thermoplasticized injectable gutta percha and resilon
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Chang Ju-Hea
Baek Seung-Ho
Lee In-Bog
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Abstract
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Objectives: The purpose of this study was to observe the change in the viscoelastic properties of thermoplasticized injectable root canal filling materials as a function of temperature and to compare the handling characteristics of these materials.
Materials and Methods: Three commercial gutta perchas and Resilon (Pentron Clinical Technologies) in a pellet form were heated in the Obtura-II system (Obtura Spartan) at and , and the extrusion temperature of the thermoplasticized materials was measured. The viscoelastic properties of the materials as a function of temperature were evaluated using a rheometer. The elastic modulus G’, viscous modulus G", loss tangent tan, and complex viscosity were determined. The phase transition temperature was determined by both the rheometer and a differential scanning calorimeter (DSC). The consistency of the materials was compared under compacting pressure at and by a squeeze test.
Results: The three gutta perchas had dissimilar profiles in viscoelastic properties with varying temperature. The phase transition of softened materials into solidification occurred at to , and the onset temperatures obtained by a rheometer and a DSC were similar to each other. The onset temperature of phase transition and the consistency upon compaction pressure were different among the materials (p < 0.05). Resilon had a rheologically similar pattern to the gutta perchas, and was featured between high and low-flow gutta perchas.
Conclusions: The rheological characteristics of the thermoplasticized root canal filling materials changed under a cooling process. The dissimilar viscoelastic properties among the materials require different handling characteristics during an injecting and compacting procedure.
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KEYWORD
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Differential scanning calorimeter (DSC), Gutta percha, Resilon, Rheometer, Thermoplasticized, Viscoelastic
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