Pyrex is specially designed to withstand high temperatures, making it the best option for heating food. However, there are other types of glass that are considered safe to cook with, too. If you’re unsure whether one of your dishes is safe for use in the microwave or oven, check the vessel's surface. It should have the words “oven-safe” printed somewhere on it, along with a temperature limitation. If you don’t see this label, assume that the dish is not heat-safe.