Investigation of Ion Release from Ni-Cr Alloy in Various Acidity Conditions

Cytotoxicity is in direct correlation to the level of ion release, with non-precious alloys having higher ion release than that of precious alloys. The most often used non-precious dental alloy is Ni-Cr alloy. The aim of the investigation was to determine the type and quantity of ions released from Ni-Cr alloy (Wiron 99(r), Bego, Germany), in acid solutions with different pH values, and to determine the influence of the type of acid solution, its pH value, and duration of interaction on ion release. The overall sample consisted of 180 pieces of Ni-Cr alloy, 60 samples submerged in each of three different solutions (buffered phosphate solutions pH 3.5 and pH6, and lactic acid solution pH 3.5). Quantity of ion release was measured on solution samples taken at 10 different time intervals by means of the ICP-AES method. Average release of Ni ions in lactic acid solution was 432.42 μg/L, while the highest average Ni+ ions release of 541.67μg/L was measured in buffered phosphate solution pH 6.0. MANOVA demonstrated significant influence of the type of solution on Ni ion release (p<0.01), while the time of exposure was not a significant factor (p=0.23). Zn ions demonstrated the lowest average ion release (88.95 μg/L, phosphate solution pH 3.5). Statistically significant influence of the type of solution and pH value on ion release was determined, except for chromium ions (p<0.05). Dentobacterial plaque acidity is sufficient to start corrosion of Ni-Cr dental alloys

A Comparison of Trace Element (TE) Release from High Noble Au-Pt Alloy and Base Co-Cr-Mo Alloy Under In Vitro Conditions of Imitating Oral Saliva

In a moist environment electrochemical conditions lead to release of metal ions into the patient\u27s saliva. The aim of this study was to examine and compare the types and quantities of metal ions released from two alloys: AuPt alloy and Co-Cr-Mo alloy under in vitro conditions, imitating artificial saliva. We soaked ten sets of Au-Pt alloy pieces having 133 mm2 exposure surface and ten sets of Co-Cr-Mo alloy (WironitR, Bego, Germany) pieces having 497 mm2 exposure surface for 1, 2, 3, 4, 5, 6, 7, 14, 21 and 30 days (six pieces each set) in phosphate buffered saline (pH 6.0) to mimic dental saliva. TE in the phosphate buffered saline (saliva) were assessed by ICP-AES (JY 50P, Jobin-Ywon, France) with the detection limit of 10 mg/L. We found detectable amounts (mg/L) of TE (Mean SD) released from Au-Pt alloy (Mean SD): Zn 124 (51), Cu 53 (63), Fe 15 (11) and Cr 18 (25) and detectable amounts of TE released from Co- Cr-Mo alloy (Mean SD): Co 337 (170), Fe 21 (15) Zn 87 (56), Ni 41 (68), and Cr 49 (42). The manufacturer did not indicate the presence of Zn and Fe in the Au-Pt alloy and the presence of Fe, Zn, and Ni in the Co-Cr- Mo alloy. Significantly higher amount of Zn was released from high noble AuPt alloy than from Co-Cr-Mo alloy (p<0.05) and a significantly higher amount of Cr was released from Co-Cr--Mo alloy than from Au-Pt alloy. There was no significant difference in the amount of Fe ions released between the two alloys (p>0.05). We must keep in mind that the amount of released TE may be much higher than the reported values after laboratory procedures (casting, polishing, etc.) and, moreover, other TE may become detectable

Trace Element (TE) Release from Two Different Base Alloys Unde Conditions Imitating Oral Saliva

Electrochemical conditions in the oral cavity lead to a release of metal ions into the patient\u27s saliva. The aim of this study was to examine and compare the types andquantities of metal ions released from two base alloys: Co-Cr-Mo alloy (WironitR, Bego, Germany) and Ni-Cr alloy (Wiron 99, Bego, Germany) under in vitro conditions imitating artificial saliva. We soaked ten sets of each alloy having 497 mm2 exposure surface for 1, 2, 3, 4, 5, 6, 7, 14, 21 and 30 days (six pieces each set) in phosphate buffered saline (pH 6.0). TE in the phosphate buffered saline (saliva) were assessed by ICP-AES (JY 50P, Jobin-Ywon, France) with the detection limit of 10 mg/L. We found detectable amounts (mg/L) of TE (Mean SD) released from Co-Cr-Mo alloy (Mean SD): Co 337 (170), Fe 21 (15) Zn 87 (56), Ni 41 (68), and Cr 49 (42) and detectable amounts of TE released from Ni-Cr alloy (Mean SD): Co 265 (300), Fe 247 (256) Zn 92 (46), Ni 542 (668), and Cr 396 (410). The manufacturer did not indicate the presence of Fe, Zn, and Ni in the Co-Cr-Mo alloy and the presence of Fe, Co and Zn, in the Ni-Cr alloy. A significantly higher amount of Fe, Ni and Cr was released from Ni-Cr alloy (p<0.05), and a considerably higher amount of Co was released from Co-Cr-Mo alloy, although it did not reach a statistically significant level (p>0.05), while there was no significant difference between the two alloys for Fe ion release (p>0.05). We must keep in mind that the amount of the released TE may be much higher than the reported values in this study, after the laboratory procedures (casting, polishing, etc.) and allergenic essential TE Cr, Co, and Ni may be present locally in a considerably higher amount

Transformation tools enabling the implementation of nature-based solutions for creating a resourceful circular city

The linear pattern of production-consumption-disposal of cities around the world will continue to increase the emission of pollutants and stocks of waste, as well as to impact on the irreversible deterioration of non-renewable stocks of raw materials. A transition towards a circular pattern proposed by the concept of ‘Circular Cities’ is gaining momentum. As part of this urban transition, the emergent use of Nature-based Solutions (NBS) intends to shift public opinion and utilize technology to mitigate the urban environmental impact. In this paper, an analysis of the current research and practical investments for implementing NBS under the umbrella of Circular Cities is conducted. A combined appraisal of the latest literature and a survey of ongoing and completed National-European research and development projects provides an overview of the current enabling tools, methodologies, and initiatives for public engagement. It also identifies and describes the links between facilitators and barriers with respect to existing policies and regulations, public awareness and engagement, and scientific and technological instruments. The paper concludes introducing the most promising methods, physical and digital technologies that may lead the way to Sustainable Circular Cities. The results of this research provide useful insight for citizens, scientists, practitioners, investors, policy makers, and strategists to channel efforts on switching from a linear to a circular thinking for the future of cities