The effect of mold temperature on castability of CP Ti and Ti-6Al-4V castings into phosphate bonded investment materials.
OBJECTIVE
The aim of this study was to evaluate the castability of CP titanium and Ti-6Al-4V alloy castings into Rematitan Plus investment at three different mold temperatures.


METHODS
A nylon mesh pattern (20 mm with 64 squares and wire of 0.7 mm in diameter) was used for the castability testing. Initially, an image of the wax pattern was obtained by means of a digital camera and the total extension of filaments (mm) was then measured, using the Leica Qwin image analysis system. The mesh sprued was placed in the Rematitan Plus investment material and the castings were made in a Discovery Plasma machine at three different mold temperatures: 430 degrees C (control group), 480 degrees C or 530 degrees C. Ten castings were made for each temperature. The images of the castings were analyzed (Leica Qwin) and the castability index determined by the number of the completely cast segments as a percentage of the wax pattern. Data were analyzed by two-way ANOVA and Tukey's multiple comparison test (a = 0.05) using materials and temperatures as discriminating variables.


RESULTS
The Ti-6Al-4V alloy (60.86%) presented a better castability index than CP Ti (48.44%) (p < 0.000001). For CP Ti, the temperature of 530 degrees C (23.96%) presented better castability than at other temperatures, 480 degrees C (14.66%) and 430 degrees C (12.54%), with no difference between them (p < 0.001). For Ti-6Al-4V alloy, there was a statistically significant difference among the three temperatures: 530 degrees C (28.36%) > 480 degrees C (19.66%) > 430 degrees C (15.97%) (p < 0.002).


CONCLUSIONS
Within the limitations of this study, the increase in the mold temperature of the Rematitan Plus investment resulted in a better castability index for both materials, and Ti-6Al-4V presented a better castability index than CP Ti.
Oliveira
Pedro César Garcia
PC
Department of Dental Materials and Prosthodontics, São Paulo State University (UNESP), Araraquara Dental School, Araraquara, SP, Brazil.
Adabo
Gelson Luis
GL
Ribeiro
Ricardo Faria
RF
Rocha
Sicknan Soares
SS
D000497:Alloys; D000704:Analysis of Variance; D003343:Corrosion; D003722:Dental Alloys; D003734:Dental Casting Investment; D003735:Dental Casting Technique; D003799:Dental Stress Analysis; D004548:Elasticity; D006244:Hardness; D008422:Materials Testing; D010710:Phosphates; D012212:Rheology; D012822:Silicon Dioxide; D013696:Temperature; D014025:Titanium
D000497:Alloys; D003722:Dental Alloys; D003734:Dental Casting Investment; D010710:Phosphates; C031462:titanium alloy (TiAl6V4); D012822:Silicon Dioxide; D014025:Titanium