Thesis
Metal ions released from copper based alloys used in dentistry and their effects on cells
- Creator
- Rights statement
- Awarding institution
- University of Strathclyde
- Date of award
- 2013
- Thesis identifier
- T13587
- Qualification Level
- Qualification Name
- Department, School or Faculty
- Abstract
- Copper-based alloys have been used as an alternative to gold based alloys for dental crown and bridge applications. Their popularity is mainly due to their bright gold-like appearance and a lower cost when compared to alloys made from noble metals. Release of metal ions (Cu²⁺ and Ni²⁺) and microparticles which may induce inflammation of the adjacent periodontal tissues and the oral mucosa has been documented in both in vitro and in vivo studies involving metallic dental devices. The primary aim of this research project was to elucidate the release of metal ions from metallic dental alloys in a simulated oral environment. Discs of copper-based dental alloy (NPGTM⁺²) with the following nominal composition [in wt %] copper 77.3: aluminium 7.8: nickel 4.3: iron 3.0: zinc 2.7: gold 2.0 and manganese 1.7 and NPGTM alloy (without gold) were obtained from Dentech Dental, London, UK. Specimens of NPGTM⁺² and NPGTM alloys (32 mm x 10 mm x 1.5 mm) were totally immersed in 10 mL of sterile simulated saliva at both neutral (pH 7.0) and acidic pH (pH 4.0) (acidic milieu simulating the condition of plaque build-up in inter-proximal space between adjacent teeth). The tubes were sealed and incubated at 37°C for 7 days with agitation. Saliva extracts were analysed for metal ion concentrations (Cu, Ni, Zn, Al and Mn) using Inductively coupled plasma mass spectrometry (ICP-MS). Metal ion release from both alloys in simulated saliva at pH 4.0 was significantly higher (for all the metals, and at all incubation times) when compared to the levels observed at pH 7.0 (2 sample T-test p-0.05). The extent of corrosion was observed at both pHs 7.0 and 4.0 for the NPGTM alloy, at incubation times 1, 3, 5 and 6 days. As would be expected from the composition, Cu ions were released to the greatest extent on corrosion. The greatest increase in corrosion, comparing pHs 7.0 and 4.0, was measured with Ni (200 fold increase), followed by Mn (90 fold increase) and Zn (30 fold increase). Au in NPGTM⁺² showed no significant difference in ion release observed in the extent of corrosion between the two alloys at either pH 4.0 or 7.0. In the in vitro study the potential toxicity of a mixture of 79 μM Cu, 25 μM Mn, 15 μM Al, 47 μM Ni and 12 μM Zn to immortalised mouse fibroblast (3T3 cell line) was investigated over 4 weeks. The composition of this mixture was equivalent to the maximal ion release from the alloys. The following parameters were measured Lactate Dehydrogenase (LDH), total cell protein content using Lowry assay, activities and expression of glutathione reductase (GR), glutathione peroxidase (GPx), catalase (CAT) and superoxide peroxidase (SOD). Oxidation stress induced by incubating 3T3 cells in metal extracts media revealed upregulation of CAT compared to controls. Differences between control and metal treated cells showed transient decrease for GR, SOD and GPx. Marked decrease observed for GR at week 2, in contrast, CAT shown transient increase at week 2. This study suggests that at least at the short term and despite considerable metal ion release from the two dental alloys, this did not lead to overt toxicity.
- Resource Type
- DOI
- Date Created
- 2013
- Former identifier
- 1001857
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