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Zobni amalgam je zlitina živega srebra s prahovi srebra, kositra, bakra in drugimi kovinami. Kljub vsebnosti živega srebra ta ni toksičen, saj se živo srebro ne nahaja v svoji elementarni obliki. Pri strjevanju po namestitvi v zobno kaviteto amalgam spreminja svoj volumen, vendar prevladuje širjenje. Zaradi hrapave mikrostrukture po strjevanju ne more nikoli popolnoma zatesniti kavitete. Priprava zlitine poteka v amalgamatorju s posebnimi kapsulami, ki omogočajo varno mešanje sestavin brez nevarnosti vdihovanja strupenih hlapov živega srebra. Pri merjenju toplotnih lastnosti po TPS metodi s sistemom Hot Disk je bila povprečna izmerjena toplotna prevodnost 21,21 W/(Mk), temperaturna prevodnost 12,63 mm2/s in specifična toplota 1,68 MJ/m3 pri sobni temperaturi 22°C. V primerjavi z vzorcem pri telesni temperaturi 37 °C se je toplotna prevodnost povečala za 1,62 W/(Mk), temperaturna prevodnost za 1,23 mm2/s, specifična toplota pa se je povečala za 0,03 MJ/(m3K). Spremembe niso drastične in bistveno ne spremenijo toplotnih lastnosti zobnega amalgama. Dental amalgam is an alloy made of mercury, mixed with silver, tin, copper and other metals powders. Despite containing mercury, the mixture isn`t toxic because it is not presented in its elemental form. After setting in tooth cavity, amalgam starts to harden and change its volume, but mostly it`s expanding. After hardening, dental amalgam is unable to completely seal cavity in which it is set in because of its rough texture . Alloy is made in amalgamator with specially designed capsules that allow safe mixing without risking inhalation of toxic mercury vapours. Measurement was made using TPS method with Hot Disk system. It showed average thermal conductivity to be 21,21 W/(Mk), thermal diffusivity 12,63 mm2/s and specific heat 1,68 MJ/m3 at room temperature of 22 °C. Compared to specimen at body temperature of 37 °C, specific heat has increased for 1,62 W/(Mk), thermal diffusivity 1,23 mm2/s and specific heat has increased for 0,03 MJ/(m3K). Changes are not drastic and dental amalgam thermal properties not esentially changed. |
