Influence of Temperature on Rheology of AH Plus and GuttaFlow

Objectives: This study aimed to investigate the influence of warm filling techniques on setting properties of Ah Plus Jet (AHPJ) and GuttaFlow bioseal (GFB).
Methods: GFB (Coltène/Whaledent, Langenau, Germany) or AHPJ (Dentsply DeTrey, Konstanz, Germany) were freshly mixed and placed on the lower plate of the dynamic rheometer Physica MCR 301 (Anton Paar, Graz, Austria). Rheological measurements were taken in oscillating mode with a strain amplitude of 0,01‰ and angular frequency (ω) of 10/rads. Each sealer was tested at temperature conditions that aimed to simulate the warm vertical compaction technique (“temperature ramp”): the material started at room temperature (20°C), was heated up to 80°C during 01 minute and cooled down to 37°C (cooling rate of 7°C/min). As a control, measurements were performed at constantly 37°C. Each measurement was performed five times. Rheological properties were calculated according to setting time and complex viscosity. Kolmogorov-Smirnov tests, Two-Way ANOVA and t tests (p<0.05) were performed to analyze the results.
Results: Elevated temperature reduced the final setting time of GFB (24.85±1.38 min @37°C vs. 4.45±0.10 min @temperature ramp; p<0.05), but not of AHPJ (1407.37±34.22 min @37°C vs. 1551.53±147.93 min @temperature ramp; p>0.05). The complex viscosity of both sealers were affected by heat (p<0.05); GFB showed an increase in complex viscosity (1.49±0.79 10E6 Pa.s @37°C vs. 2.09±0.37 10E6 Pa.s @temperature ramp; p<0.05) whereas complex viscosity of AHPJ decreased with heat (6.44±1.37 10E7 Pa.s @37°C vs. 4.7±0.41 10E7 Pa.s @temperature ramp) (p<0.05).
Conclusions: Application of heat reduced GFB setting time and increased its complex viscosity. AHPJ exhibited reduced complex viscosity when heated. Since setting time of AHPJ was not altered, this material resembles suitable for cold and warm filling techniques.