Izvorni znanstveni članak
The Release of Nickel Ions from Three Different Dental Casting Alloys
Jasmina Stipetić
Asja Čelebić
Ivo Baučić
Nives Rinčić
Alma Ćatić
Maja Baučić
Sažetak
The objective of the current study was to investigate the release of Ni ions from the following three dental casting alloys: high-noble Au-Pt alloy, and non-noble (base metal) Ni-Cr and Co-Cr- Mo alloys. The purpose of the study was also to determine whether the solution in which an alloy is submerged as well as its pH level and the exposure time have any effect on the amount of released Ni ions from the three above mentioned alloys. Three commercial alloys were used in the experiments: two base metal alloys, Ni-Cr (Wiron 99®, Bego, Germany) and Co-Cr-Mo alloy (Wironit®, Bego, Germany) and one high noble, Au-Pt alloy (Noble Metals Refinery, Zagreb, Croatia). Ni-Cr alloy samples and Co-Cr-Mo alloy samples, rollers of identical dimensions with diameters of 8 mm and heights of 15.8 mm were used, made by the manufacturer. The samples of Au-Pt alloy were plates with dimensions of 8 mm and height of 1 mm, also made by the manufacturer. All the samples were submerged in three different solutions over a certain period of time. The phosphate buffered solution at the pH = 6 level, rapresented human saliva, whereas lactic acid, to which certain amounts of acetic and formic acids, pH=3.5 (0.1 M lactic acid, 0.1 M NaCl, 1% acetic acid and 1% formic acid) were added to represent the condition that is created below dentobacterial plaque. The phosphate buffered solution ( pH=3.5), which was composed according to established pharmacopeical standards was used for comparison, since such extremely acid conditions do not exist in the oral cavity environment. Six samples were used for each tested dental alloy (n=6), for each solution separately and for each tested time interval, and thus 180 samples were used or 540 samples in total. The ion release from the above tested dental alloys in the above mentioned solutions was measured over 10 time intervals, i.e. after 1, 2, 3, 4, 5, 6, 7, 14, 21 days and 30 days respectively. Solutions were analysed by atomic absorption spectrometar with inductively coupled plasma (ICP - AES) JY 50, France. Results of the analysis lead to the following conclusions:
1. In the following dental alloys (Ni-Cr, Au-Pt, Co-Cr-Mo) the manufacturer states the presence of Ni only in Ni-Cr alloy. Results
show that Ni-Cr alloy and Co-Cr-Mo alloy released Ni ions, but the Au-Pt alloy did not, even at low pH levels.
2. During the initial period of exposure Ni ions were released from the Co-Cr-Mo alloy in small amounts (10 μg/L) while increase in ion release was observed on the sixth day in the phosphate buffered saline at pH 3.5. Significant Ni ions release also occurred on the 21st day and 30th days respectively in the phosphate buffered solution at pH 6 (artificial saliva) as well as in lactic acid at pH 3.5 (dentobacterial plaque) when amount of the Ni ion release exceeded the approved daily dietary intake of this oligo-element.
3. The Ni-Cr alloy released great amounts of Ni ions in all three solutions so that on the very first day of measurement these amounts exceeded the approved daily dietary intake of this element. Gradually, the amount of the released Ni ions increased with great variability in all solutions. However, the greatest increase in Ni ions release was noted in the phosphate buffered saline, at pH 6 level (artificial saliva) where it exceeded the approved daily dietary intake of this element. Therefore, this alloy should be used exclusively for fabrication of metal-ceramic appliances and should be fully covered by ceramic.
Ključne riječi
release; nickel; dental alloys
Hrčak ID:
10352
URI
Datum izdavanja:
15.12.2002.
Posjeta: 3.035 *