Microstructural Characterization and Physical and Mechanical Evaluation of Relevant Amalgams in Iran Dental Materials Market

Dental amalgam is considered as the most tolerable restorative dental material due to its proper physical and mechanical properties, cost-effectiveness, and long term clinical performance. In this study, the physical and mechanical properties of nine relevant amalgams in Iranian dental material market were investigated based on ISO 24234: 2015. Moreover, the morphological characterization of dental amalgam alloy was evaluated using field emission scanning electron microscopy (FE-SEM). An amalgamator was utilized to mix the amalgam alloy powder with mercury. In addition, the investigation of the microstructure of dental amalgam was conducted using FE-SEM equipped with an Energy Dispersive Spectroscopy system to analyze the composition of the elements. The required samples for the evaluation of compressive strength, creep, and dimensional changes during hardening were prepared using the recommended standard template based on the suggested program. The data were analyzed using one-way ANOVA and Tukey's test. P-value less than 0.05 was considered statistically significant. The evaluation of morphological characteristics of amalgams showed that amalgams, namely “GK-110” and “110 Plus” were prepared from lath cut particles. In addition, amalgams, such as “Cinasilver”, “Solaloy”, and “World Work” were composed of spheroid-like particles. However, alloys, including ANA 2000, Contour, SDI GS-80, and Cinalux showed mixed morphologies of spherical (or spheroid-like) and lath cut particles. Regarding the mixed alloys, “Contour Regular Kerr” and “SDI GS-80 Regular Set” contained more spherical particles. However, higher levels of lath cut particles were observed in “ANA 2000” and “Cinalux”. The homogenous and fine-grained microstructures were observed in spherical and spheroid-like particles. All studied dental amalgams comply with the requirements for creep according to the standard ISO 24234: 2015. The results of one-way ANOVA revealed that one-hour compressive strength of Cinasilver amalgam was significantly higher than that of the other amalgams (P<0.05). According to Tukey Post Hoc analysis, there was no significant difference regarding one-hour compressive strength in Contour, Cinalux, and Cinasilver (P>0.05). Out of all studied amalgams, SDI gs-80 showed the lowest coefficient of variation regarding compressive strength. In terms of the number of specimens with higher strength more than the minimum strength requirement of the standard, Cinasilver amalgam completely met the standard requirements for one hour and one day. Except for 110 Plus amalgam, the other amalgams met the requirement regarding the dimensional changes during the hardening within the specified standard range. The results indicated that amalgam “Cinasilver” met the standard requirements of ISO 24234: 2015regarding creep, dimensional changes, and compressive strength in one hour and a day.  However, amalgams, namely Cinalux, Contour, and SDI gs-80 may be considered as appropriate amalgams.