Final answer:
The T-band matrix is used for restoring primary teeth with a missing proximal surface. It is suitable for pediatric dentistry, whereas the Tofflemire matrix is more commonly employed for adult teeth.
Step-by-step explanation:
The type of matrix that is used to restore primary teeth where a proximal surface is missing is a T-band matrix. The T-band matrix is specifically designed for pediatric dentistry and is well-suited for providing the necessary shape and support to restore a primary tooth that has lost one of its sides. In contrast, the Tofflemire matrix is more commonly used for adult teeth, and preformed metal crowns are a different type of dental restoration altogether, typically used for more extensive tooth damage.