engleski

Metal ion release from the base CO▪CR▪MO, NI▪CR, andD nobleE AU▪PT dental alloy into the buffered solutions of different composition and ph value

The prevailing biological conditions in the human oral cavity induce the release of trace element (TE) metal cations from the dental casting alloys. We studied the release of metal ions (Al, Ag, Au, Ca, Cd, Co, Cr, Cu, Mg, Mo, Ni, Pd, Pt, Ti, and Zn) from three most common dental casting alloys, two base and one noble: Co▪Cr▪Mo, Ni▪Cr, and Au▪Pt alloy into three buffered biological solutions simulating the composition and pH of respective saliva, acidity, and dental plaque. The commercially available Co▪Cr▪Mo, Ni▪Cr and Au▪Pt alloy specimens were soaked in pH 6.0 phosphate buffer (Saliva), 3.5 pH phosphate buffer (Acid) and pH 3.5 mixture of lactic, formic and acetic acid (dentobacterial Plaque), and incubated at 37 0C for 1, 2, 3, 4, 5, 6, 7, 14, 21, and 30 days. Six samples (n = 6) of every solution were prepared for every time period. Inductively coupled plasma atomic emission spectroscopy was used for analysis of the released elements. The concentration of the trace elements (TE) released from soaked dental metal alloys in various solutions of different pH are expressed in µg•L-1 as Mean values (SD). Average detectable amounts of TE from the Co▪Cr▪Mo dental alloy were released into: Plaque Co 502 (412), Acid Cr 589 (84), Plaque Fe 180 (43), Acid Ni 80 (96), and Acid Zn 87 (56). The manufacturers did not indicate the presence of Fe, Ni, and Zn. Average detectable amounts of TE from the Ni▪Cr dental alloy were released into: Acid Co 347 (394), Saliva Cr 397 (491), Saliva Fe 248 (257), Saliva Ni 542 (669), and Plaque Zn 96 (51). The manufacturers did not indicate the presence of Co and Zn. Average detectable amounts of TE from the Au▪Pt dental alloy were released into: Acid Cr 895 (14), Plaque Cu 113 (79), Plaque Zn 207.4 (25.3), and Acid Fe 150 (43). The manufacturers did not indicate the presence of Cr and Fe. ANOVA revealed the significant effect of alloy composition, the respective buffer solution (Saliva, Acid, Plaque), time interval (1 to 30 days), and interaction on ion release (P<0.001 for every compared parameter). There was a great within the buffer solition variability in metal ion release from the same dental alloy indicating their inhomogeneity. The base metal alloys virtually released more ions than the Au▪Pt alloy, however their effective surface area was larger than that of noble alloy. The ion release from an alloy doesn't necessarily correlate with the abundance of the element in the alloy. Rather, there is a selective dissolution so that the elements that are present in alloys only in traces can be released from them in larger amounts. The concentration of the major essential TE of Cu, Fe and Zn released from base dental alloys was below the Reccomended Dietary Allowances (RDA's), whereas the leaching concentrations of the allergogenic Co, Cr, and Ni were substantial. Considerable amounts of Ni was released from Ni▪Co dental alloy, whereas undeclared Co from the Ni▪Cr alloy and undeclared Ni from the Co▪Cr▪Mo alloy may have both local and systemic, especially allergognic, adverse effects. The undeclared chromium from noble Au▪Pt dental alloy appears to be responsible for the contact allergy thus far attributed to the gold.

Co▪Cr▪Mo dental alloy, Ni▪Cr dental alloy, Au▪Pt dental alloy, metal ion release, buffered solutions, saliva, plaque, acid

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