When choosing dishes and food storage containers, it is important to consider how these will be used. Some dishes and containers are sold as being safe to use in a microwave oven. Other dishes and containers are sold as being safe to use in a conventional oven. However, dishes or containers that are "microwave-safe" are not necessarily "oven-safe."
Microwave-safe plastic dishes and containers have been tested and are safe for use in microwave ovens. However, the plastic in these containers is not intended to be used under high heat for long periods of time. If these containers or dishes are subjected to such conditions -- the kind found in a conventional oven -- they can melt. The melted containers or dishes would ruin the food, the containers themselves and possibly the oven; don't use them in a conventional oven.
Non-Metallic Oven-Safe Containers
Some oven-safe containers and dishes may be used in both conventional and microwave ovens. These containers or dishes will explicitly state that they are "microwave-safe" and "oven-safe." Some examples include Pyrex, ceramic and stoneware pieces.
Oven-Safe But Not Microwave-Safe
Metallic cookware, dishes and containers are usually oven-safe; however, metal objects should never be placed inside a microwave oven. Because of the microwaves' reflection off the metal, uneven cooking or oven damage can result.
If You Are Unsure
If the container, cookware or plate is not labeled as either "oven-safe" or "microwave-safe," do not place the item in either type of oven. This will prevent damage to the item or to the oven.