J Korean Acad Conserv Dent.  2011 Sep;36(5):377-384. 10.5395/JKACD.2011.36.5.377.

Rheological characterization of thermoplasticized injectable gutta percha and resilon

• Chang J
• Baek SH
• Lee IB

• KMID: 2176575
• DOI: http://doi.org/10.5395/JKACD.2011.36.5.377

Abstract

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 140degrees C and 200degrees C, 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 tandelta, and complex viscosity eta* 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 60degrees C and 40degrees C 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 40degrees C to 50degrees C, 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.

Keyword

Differential scanning calorimeter (DSC); Gutta percha; Resilon; Rheometer; Thermoplasticized; Viscoelastic

MeSH Terms

Elastic Modulus
Gutta-Percha
Handling (Psychology)
Hot Temperature
Phase Transition
Root Canal Filling Materials
Viscosity
Gutta-Percha
Root Canal Filling Materials

Figure

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  Figure 1 Rheological characteristics of the three gutta perchas and Resilon as a function of temperature. (a) Storage (elastic) modulus, G'; (b) Loss (viscous) modulus, G"; (c) Loss tangent, tan δ; (d) Complex viscosity, η*. OBT, Obtura; DIA, Diadent; MET, Meta; RES, Resilon.

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  Figure 2 Comparison of the consistency of the canal filling materials using a squeeze test at 60℃ and 40℃. OBT, Obtura; DIA, Diadent; MET, Meta; RES, Resilon.

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