nayereh asgari

This study investigates the use of three refractory metals, their names are titanium (Ti), niobium (Nb) and zirconium (Zr), in combination with iron (Fe), chromium (Cr) and vanadium (V) to produce high entropy bioalloys. . Three high entropy alloy compositions, namely TiZrNbCrV, TiZrNbFeCr and TiZrNbFeV, were made using mechanical alloying technique and powder metallurgy method. Investigation about alloys was done through X-ray diffraction analysis (XRD) and field emission scanning electron microscope (FE-SEM) studies. The present study has shown that gradual cooling after the sintering process leads to the creation of a small percentage of compact hexagonal phases (HCP) in each of the three investigated alloys. In addition, two of the investigated alloys showed the formation of intermetallic phases due to the same cooling process. The microstructure of manufactured alloys includes four regions for all alloys containing the main Body-centered cubic ) BCC(, partial HCP (and other phases), voids, and Nb-containing regions.

 In luting cements, the compressive strength characteristics are important. Sufficient radio opacity for luting cements is helpful in detecting recurrent caries, open gingival margins and residual luting materials. The aim of the present study was to conduct a comparative evaluation of compressive strength and radio opacity between Fuji I glass ionomer (GC, Japan)  and Iranian glass ionomer luting cements ( produced by Qazvin Ava Tajhiz Co).

In this study, 20 samples were prepared for each cement group. The specimens were prepared with a powder to liquid ratio (1.8/1) and after mixing were poured in mold with a height of 6 mm and a diameter of 4 mm. Then; we evaluated the strength of the specimens. In the radio opacity study, the cement mixture was poured into mold with 15 mm in diameter and 1 mm in thickness. Then the specimens were tested using a digital radiography apparatus. Using Digora for Windows software, radiopacity of the samples were evaluted.

There was no significant difference between Fuji I (59.48 MPa) and Iranian cement (58.92 MPa) in regard to compressive strength (P=0.89). Radio opacity of Fuji I (2.4mmAl) was significantly higher than that of Iranian cement (1.85mmAL) (P =0.003).

The results of this study showed that both properties of compressive strength and radio opacity of the cements were within the range of ISO 9917-2: 2010. If other properties of the Iranian cement are suitable, it can be considered as an alternative to Fuji I glass ionomer cement.

Comparing the net setting time and radiopacity of an Iranian glass ionomer cement (GIC) and Fuji II (GC, Japan) according to ISO 9917‑1:2007 standard.

In this experimental/in vitro study, for both tests, we prepared 20 samples of Fuji II glass ionomer(self‑cure restorative glass ionomer, batch number: 1608031, GC Corporation, Tokyo, Japan) and Iranian glass ionomer (Ava Tajhiz Dandan‑Iran) at P/L of 2/7:1. Then, to determine the net setting time, we prepared a metal mold with dimensions of 10 mm in length, 8 mm in width, and 5 mm in height. Ninety seconds after mixing, the surface of the sample was subjected to the indenter, and the net setting time was recorded as the time elapsed between the end of the mixing and the time needle stopped making a complete circular indentation. To determine radiopacity, the specimens were poured into a mold with a diameter of 15 mm and thickness of 1 mm. Samples and a step wedge were irradiated with X‑rays. Particle size analysis and Energy‑dispersive X‑ray spectroscopy (EDS) analysis were also done for both cements. Test results were investigated with SPSS and through independent t‑test (P < 0.05).

The mean value of net setting time for Fuji II was 4.83 min and for the Iranian Glass ionomer was 3.83 min (P < 0.05). The mean value of radiopacity for Fuji II was 2.3 mmAL and for Iranian Glass ionomer was 1.9 mmAl (P < 0.05).

Net setting time and radiopacity of the glass ionomers were within the range of ISO 9917‑1:2007. If all properties of the Iranian cement are set appropriately in future investigations, we propose to use it instead of Fuji II GIC. This has the additional benefit of being cost‑efficient as Iranian cement costs less than Fuji II cement.