PSI - Issue 74

Hrubanová A. et al. / Procedia Structural Integrity 74 (2025) 33–37 Anna Hrubanová / Structural Integrity Procedia 00 (2025) 000–000

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found between Zetaplus, Elite HD+ and Ipregum Soft. The mean values (± SD) can be found in Tab.2. All statistical analyses were performed using software Minitab (Minitab 2007).

Table 2. The values of strength, fracture strain and porosity (± SD) for each of the materials.

Elastomeric impression material

Strength [MPa]

Fracture strain [-]

Porosity [-]

Zetaplus

1.09 ± 0.05 1.38 ± 0.03 0.50 ±0.08 0.93 ± 0.16

0.67 ± 0.06 1.02 ± 0.13 2.20 ± 0.22 1.12 ± 0.36

0 ± 0.00 0 ± 0.00

Elite HD+ Putty Soft Permlastic Regular Body

0.03 ± 0.03 0.03 ± 0.01

Impregum Soft

Three regions of interest (ROIs) were created for each specimen in ImageJ software (Schneider, Rasband, and Eliceiri 2012). ROIs could not be created near the edges of specimens due to imperfections caused by mould cavities for the removal of excess material. For specimens with a thickness of 1.5 mm, the ROIs were cubic with an edge length of 1 mm; for specimens with a thickness of 2.5 mm, the ROIs were cubic with edge length of 2 mm. In total, 24 regions of interest were created. Porosity (defined as the ratio of the void volume to the total volume of ROI) was evaluated within each region of interest; mean values (± SD) for each material are presented in Table 2. Regions of interest for Impregum soft and Permlastic are shown in Fig.3. Higher variability in porosity of Permlastic was caused by a moderate quantity of larger bubbles, whereas Impregum Soft contained a greater quantity of smaller pores.

Fig. 3. Region of interest: A - Permlastic (1.5mm thickness) with porosity 0.01, B – Impregum Soft (1.5mm thickness) with porosity 0.04, C - Permlastic (2.5mm thickness) with porosity 0.07, D – Impregum Soft (2.5mm thickness) with porosity 0.04 4. Discussion The uniaxial tensile tests revealed different tensile properties for all four materials. Material Elite HD+ Putty exhibited the highest strength and the lowest fracture strain, while material Permlastic showed the lowest strength but highest fracture strain. The uniaxial tensile strength of Impregum Soft was found to be 0.93 ± 0.16 MPa, which is comparable to the values of 1.2 ± 0.2 MPa reported by (Lu, Nguyen, and Powers 2004). The strength of Zetaplus (1.09 ± 0.05 MPa) was significantly lower than the values reported by (Wezgowiec et al. 2022) (1.69 ± 0.13 MPa). This discrepancy can be due to the lack of precise ratio in which the base paste and catalyst should be mixed; a higher amount of catalyst could lead to increased strength values. While the Zetaplus and Elite HD+ Putty exhibited almost bilinear stress-strain response, nonlinear behaviour was prominent throughout the entire curves for the two remaining materials. Thus, the two groups can be differentiated by their strength (higher for Zetaplus and Elite HD+ Putty), fracture strain (lower for the two aforementioned materials) and porosity (no cavities were found in the two materials). This may be attributed to their initial form, as both materials had higher viscosity after mixing. The higher porosity (Fig. 3) observed in Impregum Soft and Permlastic can also be attributed to the mixing technique, where air bubbles may have been introduced during the manual combination of the two pastes.