Dental alloys alloying elements

Platinum, as an alloying element, is used in many dental casting golds (Tables 6 and 7) to improve hardness and elastic qualities. Platinum in combination with palladium and iridium has limited use for dental pins and wires. 

A variety of dental alloys were submitted to adsorption experiments with human saliva. FT-IR and SIMS were used to analyze the surface films. lEF compared the protein patterns from surface extracts and salivas used in protein adsorptions to those from unexposed saliva controls. Results support both selective and nonselective adsorption processes. The SIMS spectrum showed variabilities in elemental intensities between substrates of different compositions, while lEF patterns of surface extracts from eleven different compositions of powder all appeared to contain the same acidic protein bands. FT-IR spectrum showed variabilities in the protein to carbohydrate intensity ratios at different sites on the same alloy surface, and suggested that other factors besides substrate material may be important in protein adsorption. 

The lateral resolution of 0.5 allows experiments at the subcellular level. Initial work has concentrated on the localization of elements In specific sites of the tissue. Typical examples involve the assessment of aluminium levels in the bones of chronic haemodialysis patients, the study of lead accumulation in kidneys and calcifications in intraperitoneal soft tissue as a result of chronic lead intoxication, and the detection of several heavy metals in the amalgam tattoos of the oral mucose membrane and human gingiva in direct contact with dental alloys. The relatively low lateral resolution, the lack of automated mapping and the almost impossible quantization strongly hinder the use of LMMS, especially in view of analytical electron microscopy (AEM) with X-ray analysis and the emerging possibilities of nuclear microscopy. 

Alloying Elements for Gold-Based Dental Alloys.304... 

The addition of 10 wt% palladium renders the alloy white (or silver) in color and shifts the hardening mechanism to solid-solution strengthening. Base element additions are indium, tin, gallium, and zinc. These are the most popular dental alloys because they can be easily modified to suit different porcelains and economic needs. 

Solders. Modem dental solders are made from mostly corrosion-resistant, nontoxic metals. Minimal quantities of tin and other elements are often added, some of which could produce toxic effects in the unalloyed state. Each solder is used for specific appHcations (180—188) typical compositions and properties of solders used in dentistry are presented in Table 11. Most of the ingredients of solders are resistant to corrosion, and alloying them with other ingredients renders the alloy safe for use in appHances placed in the oral environment. Silver solders corrode, but are used only for temporary appHances. Available products do not contain cadmium, although cadmium was an ingredient of some silver solders up to ca 1980. 

Ruthenium alloyed to platinum, palladium, titanium and molybdenum have many apphcations. It is an effective hardening element for platinum and palladium. Such alloys have high resistance to corrosion and oxidation and are used to make electrical contacts for resistance to severe wear. Ruthenium-palladium alloys are used in jewelry, decorations, and dental work. Addition of 0.1% ruthenium markedly improves corrosion resistance of titanium. Ruthenium alloys make tips for fountain pen nibs, instrument pivots, and electrical goods. Ruthenium catalysts are used in selective hydrogenation of carbonyl groups to convert aldehydes and ketones to alcohols. 

Daniel Gray perfected a stable bath from which indium can be plated simultaneously with other elements (90). Alloyed with precious metals, indium has been made into jewelry, alloyed with silver, it is sometimes used to plate silverware with a suiface resistant to tarnish in the form of an amalgam, it can be used for dental fillings (88, 89, 93) The portraits of Reich and Richter and much of the information about indium have been obtained through the kind assistance of Professor L. W. McCay of Princeton University and Professor O. Brunck, Rectoi of the Freiberg Academy. 

An accurate determination of copper and zinc traces in human serum samples from the International Measurement Evaluation Programme-17 launched by IRMM (Geel) has been made by isotope dilution TIMS.38 An analytical method for the multi-element determination of metals (Ti, V, Cr, Co, Ni and Mo) potentially released from dental implants and prostheses into human body fluids (in blood and urine) by ICP-MS (double-focusing sector field instrument and quadrupole instrument with octopole collision cell) for medical studies was developed in Sanz-Medel s group.39 The Cr and Co concentrations found in blood samples of patients with chromium-cobalt based alloy varied in the sub-p,gl 1 range and were not significantly higher than the basal levels found by other authors.40... 

J. Begerow, L. Dunemann, Internal platinum and palladium exposure of the general population with emphasis on the exposure from automobile exhaust and dental restorative alloys, in F. Zereini, F. Alt (eds), Anthropogenic Platinum-group Element emissions. Their Impact on Man and Environment, Springer, Berlin, 2000, pp. 227 D 236. 

The variation of biomedical alloys is determined by their application. More than 30 different elements are currently used for dental materials and surgical implants. Other metals (e.g., Ce, Cs, Se) are added in alloys for needles and tools applied in acupuncture and hair transplantation. 

Because of its resistance to corrosion, gold is an ideal metal for dental crowns and caps, which accounts for about 3% of the annual use of the element The pure metal is too soft to use in dentistry, so it is combined with other metals to form alloys. 

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