Mechanical and Physical Properties of an Experimental Chemically and Green-Nano Improved Dental Alginate after Proven Antimicrobial Potentials

Abstract

Objectives: Impression materials could be a source of cross-contamination due to the presence of microorganisms from blood and saliva inside the oral cavity. Nevertheless, routinely performed post-setting disinfection could compromise the dimensional accuracy and other mechanical properties of alginates. Thus, this study aimed to evaluate detail reproduction, dimensional accuracy, tear strength, and elastic recovery of new experimentally prepared self-disinfecting dental alginates. Methods: Two antimicrobial-modified dental alginate groups were prepared by mixing alginate powder with 0.2% silver nitrate (AgNO3 group) and a 0.2% chlorohexidine solution (CHX group) instead of pure water. Moreover, a third modified group was examined by the extraction of Boswellia sacra (BS) oleoresin using water. The extract was used to reduce silver nitrate to form silver nanoparticles (AgNPs), and the mixture was used as well in dental alginate preparation (BS + AgNP group). Dimensional accuracy and detail reproduction were examined as per the ISO 1563 standard guidelines. Specimens were prepared using a metallic mold engraved with three parallel vertical lines 20, 50, and 75 µm wide. Detail reproduction was evaluated by checking the reproducibility of the 50 µm line using a light microscope. Dimensional accuracy was assessed by measuring the change in length between defined reference points. Elastic recovery was measured according to ISO 1563:1990, in which specimens were gradually loaded and then the load was released to allow for recovery from the deformation. Tear strength was evaluated using a material testing machine until failure at a crosshead speed of 500 mm/min. Results: The recorded dimensional changes between all tested groups were insignificantly different and within the reported acceptable values (between 0.037–0.067 mm). For tear strength, there were statistically significant differences between all tested groups. Groups modified with CHX (1.17 ± 0.26 N/mm) and BS + AgNPs (1.11 ± 0.24 N/mm) showed higher tear strength values compared to the control (0.86 ± 0.23 N/mm) but were insignificant from AgNO3 (0.94 ± 0.17 N/mm). All tested groups showed elastic recovery values that met both the ISO standard and ADA specifications for elastic impression materials and tear strength values within the acceptable documented ranges. Discussion: The CHX, silver nitrate, and green-synthesized silver nanoparticles could be promising, inexpensive alternatives for the preparation of a self-disinfecting alginate impression material without affecting its performance. Green synthesis of metal nanoparticles could be a very safe, efficient, and nontoxic method, with the advantage of having a synergistic effect between metal ions and active chemical constituents of plant extracts.

Comparison of the Bioactive and Bacteriostatic Performance of Different Alginate-Based Dental Prosthetic Impression Materials with and without Zirconium Phosphate-Based Ion Exchange Resin Containing Silver: An In Vitro Study

“…This may be attributed to the sufficient flow and the non-altered viscosity of the alginate impression before gelation. The obtained results are consistent with Singer et al 2023 [22]. This may be due to the fact that the powder particles in this type of material have a granularity of less than 100 microns.…”

“…This phenomenon can be explained by the higher calcium/sodium ratio and the lower organic and water content of the extended-pour alginates compared to the conventional ones [33]. A reduction in the concentration of calcium ions in the composition of alginate powder was found to increase the swelling capacity of alginate chains and, consequently, cause expansion of the material [22].…”

“…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 alginates 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].…”

“…Therefore, it would be desirable to create an alginate material formulation with inherent antibacterial properties. There are reports that describe the addition of various types of chemical substances that have antibacterial properties: ceramic negative ions [9], silver [21], 0.2% silver nitrate, 0.2% chlorohexidine solution [22], chitosan [23], and silver nanoparticles [24,25]. However, a large part of this research focusses on the addition of a germicidal substance to the water-alginate mixture, which is clinically undesirable because it complicates the preparation of the alginate sol.…”

“…There are a number of papers in the literature describing the addition of silver to alginate materials. However, their use requires adding silver in the form of a solution [22,24] that is not desired by the end user. The addition of silver nanoparticles to the powder can change the colour of the alginate material itself towards grey.…”