DIANA DIACONU POPA, ANCA VITALARIU, CATALINA HOLBAN CIOLOCA, ANDRA AUNGURENCEI, ODETTE LUCA, MONICA TATARCIUC RESEARCHES ON THE INFLUENCE OF THERMAL TREATMENT ON THE MECHANICAL PROPERTIES OF TITANIUM DENTAL PROSTHESES The longevity of dental prostheses depends on the strictness of following the clinical-technological algorithm. The main method of obtaining the metallic dental prostheses is casting, which involves a succession of stages that may produce modifications in the alloy structure, that will lead to alteration of its biological and mechanical behaviour. The modification of some technological parameters influences the internal microstructure and, implicitly, the mechanical properties of the metallic dental prostheses.The paper aims to investigate the influence of cooling rate on the mechanical properties of the titanium moulded pieces. We realized 40 samples divided in four groups consisting of 10 samples each: one group as control, and three test groups. The 30 test samples underwent a thermal treatment of homogenization, represented by a heating process up to 400 °C on 0.1° C per second. The samples were maintained at 400 °C for 2 min , and, after that were cooled at different rate: group 2: 70°C/s, group 3: 30°C/s, and group 4: cooled with an average rate, varying from 30 to 70 °C/s. Group 1 was the control group consisted in 10 samples without thermal treatment. The results showed that mechanical properties of the control group are inferior comparing to the samples submitted to the thermal treatment. Among the three groups of samples that have been thermal treated, the samples that have been cooled at an average rate, varying from 30 to 70 °C/s(group 3), have optimal mechanical properties.