Thermal expansion of prepared dental base-metal casting alloys

Abstract EN

Background: The aim of the study was to evaluate the linear thermal expansion of prepared Ni-Cr and Co-Cr dental base-metal casting alloys which were prepared locally in Iraq and compare with other conventional alloys.

Materials and methods: Cylindrical shape wax specimen were prepared of 15mm length and 5mm diameter which were invested in phosphate-bonded investment material and casted by using induction casting machine.

The liner thermal expansion was tested by using Iraqi made dialometer in which the furnace was set to reach from room temperature to 950 °C in a rate of 10 °C per minute.

Results: The prepared Ni-Cr and Co-Cr alloys showed a higher linear thermal expansion than the conventional alloys, however, statistical analysis revealed non significant differences regarding the Co-Cr alloys and highly significant difference regarding the Ni-Cr alloys.

Conclusion: In comparison of locally made and other conventional alloys, Co-Cr alloys statistically revealed no difference while Ni-Cr alloys showed a difference.

Key words: Thermal expansion, Co-Cr alloy, Ni-Cr alloy.

(J Bagh Coll Dentistry 2008; 20(1)8-13)