Which type of materials are preferred for metal-ceramic alloys regarding investments?

Phosphate bonded materials are preferred for investments in metal-ceramic alloys at higher temperatures due to their ability to withstand the thermal expansion and contraction required during the firing process. These materials exhibit better dimensional stability and can accommodate the significant heat produced during the bonding of ceramics to metals.

When working with metal-ceramic restorations, it is critical that the investment material provides accurate dimensional reproduction and maintains its integrity throughout the entire firing process, which can reach high temperatures. Phosphate bonded investments are known for their high melting points and thermal resistance, making them suitable for applications where metals are fused at elevated temperatures.

In contrast, gypsum bonded materials may be limited in their thermal stability and could potentially deform or expand at higher temperatures, leading to inaccuracies in the final restoration. This is why phosphate bonded materials are specifically sought after in these applications, particularly when the alloys involved require high precision under thermal stress.