Issue 28

A. Brotzu et alii, Frattura ed Integrità Strutturale, 28 (2014) 19-31; DOI: 10.3221/IGF-ESIS.28.03

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 4.116 (±0.099)MJ/m 3 K 2.376 (±0.127)MJ/m 3 K

Heat Capacity at T Env

Heat Capacity at T=37°C 3.535 (±0.373)MJ/m 3 K 2.021 (±0.200)MJ/m 3 K

Tools SaverGel

3.854 (±0.176)MJ/m 3 K 1.973 (±0.198)MJ/m 3 K

EDTAbased emulsion

Table 2 : Heat Capacity comparisonbetweenTool SaverGel andEDTAbased emulsion.

Y ELLOW INSTRUMENTTESTRESULTS

T

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.

Break/damage evolutions

Break/damage cycles

Simulators employed

Instrument n

Lubricant

Damage type

13 14 15 16 17 18 19 20

No

350

5

2 8 6 7 8

Unwinding at revolution 9

G.S. G.S.

2065 1545 1820 1960 4340 1050 1213

30 23 27 28 62 15 17

Break at revolution 4 Break at revolution 4 Break at revolution 4 Break at revolution 9 Break at revolution 9

No

G.S. G.S.

16

EDTA EDTA

4 5

Unwinding at revolution 7 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.

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