## 3 Results and Discussion
### Mechanical Properties  
The materials were analysed in accordance with the ISO standard to verify their compliance with the requirements given for the impression materials. The results are collected in Table 5.  
The mechanical resistance of commercial materials to compression is from 0.84 to 1.07 MPa. The obtained new alginate materials X1-X3 all have a resistance of \(\sim\)0.85 MPa, which is comparable to commercial materials and meets the normative requirements of 0.35 MPa. Elastic recovery is the ability of the material to return to its original shape and, according to ISO 21563:2021 [32], must be greater than 95%. The alginate masses have typical elastic recovery at the level of 95-97%, which is a lower value than, for example, silicone materials, where the value of this parameter is 96-99.5% [40]. The results obtained indicate that all of the studied materials meet these requirements and are comparable to those of the commercial samples. This value can be variable and depends on the type of sulphate used for the alginate material and the concentration of sodium alginate itself in the material [22; 24], the authors of which studied the modification of alignates by means of nanosilver particles in water. The addition of a bacteriostatic agent as an intertwining material may reduce the value of elastic recovery [5].  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Material**} & **Compressive** & **Elastic Recovery** & **Strain in** & **Tearing** \\  & **Strength [MPa]** & **[\%]** & **Compression [\%]** & **Strength [MPa]** \\ \hline Kromopan & 1.04 \(\pm\) 0.018 [FOOTNOTE:8]Footnote 8: The material is composed by a  
The compression strain according to the above-mentioned standard must be less than 20%. The tested samples have these values in the range of \(\sim\)11-12%, exceeding the performance of Kromopan and Elastic Cromo. The tearing strength of alginate materials according to the previous ISO standard must be greater than 0.35 [MPa]. All tested materials have this value at the level of 0.44-0.57 MPa, passing the test; however, the addition of AlphaSan reduces the tearing strength of alginate materials along with increasing loading of the additive. These values are lower than those obtained in the study by [PERSON] et al., 2023, who investigated the addition of silver nanoparticles to the alginate material and obtained values of 1.11 [MPa]. In the literature, such values vary from 0.4 to 1.2 N/mm [33; 41]. It has been hypothesized that tear strength could be affected by certain factors, including the degree of crosslinking of the set alginate [42]. An increase in tensile strength can be achieved by reducing the amount of water used to decrease the alginate mass by 50% [41], without compromising the properties of the impression obtained.  
In the case of compressive strength, no differences were observed when increasing the content of the bacteriostatic agent. Other authors [PERSON] et al. [9], when adding more ceramic-based bactericidal agents, observed an increase in compressive resistance. The difference in the results may be due to the composition of the ceramic itself, the content of monovalent silver ions present in AlphaSan, which may react with the alginate carboxylic groups competitively with the divalent calcium ions responsible for the crosslinking reaction. This effect would explain the increasing drop in the tensile strength of the formulations accompanying the increasing loading of AlphaSan. The gelling process of the alginate mass itself occurs when approximately 10% of the alginate carboxyl groups are crosslinked with calcium ions [43].