Issue 28

A. Brotzu et alii, Frattura ed Integrità Strutturale, 28 (2014) 19-31; DOI: 10.3221/IGF-ESIS.28.03 24 the Aqueous gel lower than that in the EDTA based emulsion. This increase in temperaturemay promote the viscosity loss and the emulsion component separation. Sample Heat Capacity at T=4°C Heat Capacity at T Env Heat Capacity at T=37°C Tools SaverGel 4.116 (±0.099)MJ/m 3 K 3.854 (±0.176)MJ/m 3 K 3.535 (±0.373)MJ/m 3 K EDTAbased emulsion 2.376 (±0.127)MJ/m 3 K 1.973 (±0.198)MJ/m 3 K 2.021 (±0.200)MJ/m 3 K Table 2 : Heat Capacity comparisonbetweenTool SaverGel andEDTAbased emulsion. Y ELLOW INSTRUMENTTESTRESULTS able 3 reports the results of the test performed on the yellow instruments. Fig. 7 and 8 show the load vs. displacements curves of the extraction test carried out with andwithout the lubricant use. Instruments tested without lubricant gel fail in two different ways. Instrument number 13 shows a macroscopic unwinding (Fig. 9 and 10). It can be observed that unwinding is clearly visible already before the extraction test. This kind of damage is probably caused by rotation of instruments inside the canal and not by tensile load applied during the extraction phase. The instrument number 16 instead suddenly breaks, approximately at the tip, without showing any macroscopic failure signs before the last test cycle. The instruments tested with lubricant gel have shown this last kind of failure, observedby SEM. Instrument n Lubricant Break/damage evolutions Break/damage cycles Simulators employed Damage type 13 No 350 5 2 Unwinding at revolution 9 14 G.S. 2065 30 8 Break at revolution 4 15 G.S. 1545 23 6 Break at revolution 4 16 No 1820 27 7 Break at revolution 4 17 G.S. 1960 28 8 Break at revolution 9 18 G.S. 4340 62 16 Break at revolution 9 19 EDTA 1050 15 4 Unwinding at revolution 7 20 EDTA 1213 17 5 Unwinding at revolution 7 Table 3 : Yellow instrument test results. Figure 7 : Load vs displacements plot of the extraction test carriedout with gel lubricant. Figure 8 : Load vs displacements plot of the extraction test carriedout without gel lubricant. T