Efecto de las variaciones térmicas durante la fusión de los colados en prótesis fija
ABSTRACT: Physical and chemical properties of dental alloys are very important for using these alloys in humans. Cast procedure can modify this properties if melt temperature is modified. In this thesis, the bibliography remark that physical and chemical properties depends on grain sizes, and grain size can be modified depending on melt temperature. A) Objectives: 1. Describe the grains of the studied alloys. 2. Classify alloys in monophasical or multiphasical. 3. Evaluate variation of grains size depending on melt temperature. 4. Evaluate variation of grains size depending on heat treatment. 5. Test changes in hardness when melt temperature is changed 6. Test changes in hardness depending on heat treatment. 7. Test the effect of melt temperature on abrasive wear of studied alloys. 8. Test changes in corrosion resistance when melt temperature is changed. 9. See general influence of melt temperature on uses of dental alloys. In this study we used three commercial alloys for odontological use, one type IV gold alloy, Pontor 4CF (Falor-Metalor), one palladium based alloy, Cerapall 6 (Falor Metalor) and one nickel-chromium based alloy, Nibbon (Madespa-Ventura). We melt 14 0.3x10x40x mm samples using MIE 200 Automática (Ordenta) melting machine with calibrated pyrometer. The specimens were cast at different temperatures: manufacturers recommended temperature, 60 ºC under recommended temperature an 100° over it. B) Conclusions: 1. Cerapall 6 and Pontor 4CF have an equiaxial grain structure and they have monophasical composition. Nibon presents an dendrítical mutiphasical structure. 2. Grain size grows up in all tested alloys as higher is melt temperature and with heat treatment. 3. Melt temperature do not affect Cerapall 6 and Pontor 4CF hardness. Hardness improves in Nibon as melt temperature as lower. 4. Heat treatment doesnt affect hardness in Cerapall 6 and Nibon in Pontor 4CF hardness decrease at the beginning of heat treatment. 5. Melt temperature do not affect wear resistance in Nibon, but in Cerapall 6 and Nibon wear resistance is better increasing melt temperature. 6. Corrosion resistance improves as melt temperature is higher in all studied alloys. 7. AH studied alloys can be used in human varying melt temperature in the studied range.
Advisor:Peraire Ardèvol, Maria; Anglada Cantarell, Josep Maria
School:Universitat de Barcelona
Source Type:Master's Thesis
Keywords:ciències morfològiques i odontoestomatologia
Date of Publication:09/17/1999