Which of the following is not a type of stainless steel crown?

The term "stainless steel crown" specifically refers to a type of dental restoration made from a durable stainless steel material, which is typically used for primary teeth in children due to its strength and longevity. Preformed crowns and custom made crowns fall under the category of stainless steel crowns, as they are designed to cover a tooth's surface and protect it after treatment, especially in pediatric dentistry.

Polycarbonate crowns, on the other hand, are not made of stainless steel but are typically constructed from a tooth-colored plastic material, making them more aesthetic but less durable than stainless steel. They are used for anterior teeth and are not classified as stainless steel crowns.

Temporary crowns do not consist of stainless steel crowns; rather, they are often made from less durable materials and are intended for short-term use while a more permanent solution is being prepared.

Thus, the correct identification of what does not belong to the group of stainless steel crowns is indeed found in the description of polycarbonate crowns, as they are made from a completely different material than stainless steel.