OJSC Scientific and Industrial Complex “Supermetall”

D. S. Tykochinsky, Leading Researcher, e-mail: Tykochin@yandex.ru

V. V. Vasekin, Chief Executive Officer

G. S. Stepanova, Deputy Head of Department

The research objective is the creation of a new gold alloy for casting the skeletons of the metal ceramic dentures, which has a distinct yellow color. The yellow color corresponds to the consumer and aesthetic needs of some patients, because it is indicative of harmless to the health and noble metal. It is necessary to ensure the compilance with the alloy,s properties to the properties of the ceramics, which is driffed on their metal skeleton. For that, the coefficient of the thermal expansion of alloy (CTE) should be in the range of 13.5–14.5·10^–6 K^–1 when heated from 20 to 600 ^оC. The main alloying elements of the majority of gold alloys for metal ceramic, are platinum and palladium, which increase the durability characteristics. Also, in these alloys are introduced copper, tin and other precious and base metals. Adding the platinum and palladium to gold in the binary alloys results a decrease of the CTE. But the introduction of copper, silver and tin, increases it. Multidirectional influence of the alloying elements is a factor of achieving the compliance of CTE of the alloy to the given values. However, in multicomponent systems, the mutual influence of individual components on the properties of the alloy is unpredictable. This also applies to the color characteristics of the alloys, which vary in the direction of reducing the yellowness with increasing the concentration of platinum and palladium, while the other elements may have the opposite effect on the results. As an objective measure of the color, there is selected the coefficient of yellowness (YC). The YC is calculated, according to the results of the spectrophotometric researchings. In this research, the requirement for YC was given: not less than 25. Such alloys can be called a light-yellow. All the investigated alloys contain 85 % (by weight) of gold. Due to that, the high corrosion resistance and biological inertness of the finished dental-cal products is ensured. There are selected two, the most yellow alloys among the researched alloys, which fulfil the requirements both for yellowness and for CTE. Their adhesive properties meet the requirements of the State Standart GOST R 51736–2001 for metal ceramics alloys: the bond strength with ceramics, which is drifted on the surface of the metal sample, above a minimum value, equal to 25 MPa.

1. Vasekin V. V., Lebedenko I. Yu., Levchenko S. D., Rytvin E. I., Stepanova G. S., Tykochinskiy D. S. Splavy blagorodnykh metallov dlya stomatologii i akupunktury (Alloys of noble metals for dentistry and acupuncture). Moscow : Agency of sociological and marketing research, 2000. p. 68.

2. Rytvin E. I., Tykochinskiy D. S., Vasekin V. V., Lebedenko I. Yu. Dragotsennye metally. Dragotsennye kamni – Precious metals. Precious stones. 2003. No. 10. pp. 58–66.

3. GOST R 51736–2001. Metallokeramika stomatologicheskaya dlya zubnogo protezirovaniya. Tekhnicheskie trebovaniya. Metody ispytaniy (State Standard R 51736–2001. Dentistry metalloceramics for tooth replacement. Technical requirements. Testing methods).

4. Prikladnoe materialovedenie dlya ortopedicheskoy stomatologii (Applied materials science for ortophedic stomathology). 4.7. Kombinatsiya farfora s metallami (metallo-keramika) (4. 7. Combination of phosphorus with metals (metal ceramics)). pp. 1–3. Available at : http://www.orthomat.ru/part4

5. Denta-El. Metallokeramika (Denta-El. Metal ceramics). Available at : http://dentol.ru/group/1399.

6. Zolotnitskiy I. V., Lebedenko A. I. Tsvetnye Metally – Non-ferrous metals. 2009. No. 3. pp. 58–61.

7. Vasekin V. V., Tykochinskiy D. S., Levchenko S. D. Tsvetnye Metally – Non-ferrous metals. 2009. No. 3. pp. 46–49.

8. Vasekin V. V., Tykochinskiy D. S. Svoystva splavov zolota s platinoidami (Properties of gold and platinoids` alloys). PM' 2010. Platinovye metally v sovremennoy industrii, vodorodnoy energetike i v sferakh zhizneobespecheniya budushchego (PM' 2010. Platinum metals in modern industry, hydrogen energetic in the sphere of future life support). Berlin : Agency of sociological and marketing research, 2010. pp. 285–292.

9. Tsvet v promyshlennosti (Color in industry). Under the editorship of R. McDonald. Moscow : Logos, 2002. 596 p.

10. ISO 8654:1987. Tsveta zolotykh splavov. Opredelenie, diapazon tsvetov i ikh oboznacheniya : perevod s angliyskogo ; vveden 1987-08-01 (ISO 8654:1987. Colours of gold alloys. Definition, range of colors and designation : translated from English ; introduced 1987-08-01).