Slumping tendency and rheological property of flowable composites

Article information

Restor Dent Endod. 2009;34(2):130-136

Publication date (electronic) : 2009 March 31

doi : https://doi.org/10.5395/JKACD.2009.34.2.130

In-Bog Lee , Sun-Hong Min , Sun-Young Kim , Byung-Hoon Cho , Seung-Ho Back

Department of Conservative Dentistry, School of Dentistry, Seoul National University, Korea.

Corresponding Author: In-Bog Lee. Department of Conservative Dentistry, School of Dentistry, Seoul National University, 275-1 Yeongeon-Dong, Jongno-Gu, Seoul, 110-768, Korea. Tel: 82-2-2072-3953, Fax: 82-2-2072-3859, inboglee@snu.ac.kr

Received 2008 December 11; Revised 2009 February 27; Accepted 2009 March 03.

Abstract

The aim of this study was to develop a method for measuring the slumping resistance of flowable resin composites and to evaluate the efficacy using rheological methodology.

Five commercial flowable composites (Aelitefil flow:AF, Filtek flow:FF, DenFil flow:DF, Tetric flow:TF and Revolution:RV) were used. Same volume of composites in a syringe was extruded on a glass slide using a custom-made loading device. The resin composites were allowed to slump for 10 seconds at 25℃ and light cured. The aspect ratio (height/diameter) of cone or dome shaped specimen was measured for estimating the slumping tendency of composites. The complex viscosity of each composite was measured by a dynamic oscillatory shear test as a function of angular frequency using a rheometer. To compare the slumping tendency of composites, one way-ANOVA and Turkey's post hoc test was performed for the aspect ratio at 95% confidence level. Regression analysis was performed to investigate the relationship between the complex viscosity and the aspect ratio. The results were as follows.

1. Slumping tendency based on the aspect ratio varied among the five materials (AF < FF < DF < TF < RV).

2. Flowable composites exhibited pseudoplasticity in which the complex viscosity decreased with increasing frequency (shear rate). AF was the most significant, RV the least.

3. The slumping tendency was strongly related with the complex viscosity. Slumping resistance increased with increasing the complex viscosity.

The slumping tendency could be quantified by measuring the aspect ratio of slumped flowable composites. This method may be applicable to evaluate the clinical handling characteristics of flowable composites.

Keywords: Slumping tendency; Rheological property; Flowable composite; Complex viscosity; Dynamic oscillatory shear test

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This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Figure 1

Schematic diagram of composite loading device.

Figure 2

a) Lateral view of cured flowable composites after slumping for 10 s at 25℃. b) Aspect ratio (height/base diameter) of cured slumped composite was measured to compare the slumping tendency among composites.

Figure 3

Aspect ratio of slumped flowable composites. Higher aspect ratio means that the material has higher slumping resistance.

Figure 4

Representative curves of complex viscosity of composites as a function of angular frequency in a dynamic oscillatory shear - frequency sweep test. The viscosity very rapidly decreased with increasing frequency (a: logarithmic plot, b: linear plot).

Figure 5

Regression analysis showed that the aspect ratio of composites as a function of complex viscosity η^*_{ω=0.1 rad/s} is well fitted to a nonlinear curve y=ln(a+bx)(y: aspect ratio, x: complex viscosity η^*) (R=0.978).

Table 1

The flowable resin composites used in this study.

Table 2

Post-slumped aspect ratio and complex viscosities at varying oscillation frequency of flowable composites.

Different superscripts mean that there is statistically significant difference (P<0.05).