Which matrix system is typically associated with posterior Class II restorations and uses a retainer?

• A. Tofflemire matrix
• B. Sectional matrix
• C. Siqveland matrix
• D. Wedges

Answer: (A)

For posterior Class II restorations, you need a matrix that can form a stable proximal wall around the tooth so the filling material has a defined boundary and the contact with the adjacent tooth is restored. The Tofflemire matrix is the classic retainer-based system for these teeth. It uses a metal retainer that fits around the tooth and a matrix band that runs through the retainer, creating a solid wall as you place and cure the restorative material. Its adjustability for different tooth sizes and its ability to hold the matrix snugly make it the standard choice for achieving predictable contours and contacts on posterior teeth. Wedges are used to seal and adapt the band, but the matrix itself provides the essential proximal wall. Other systems, like sectional matrices, use a different retainer mechanism (a tension ring or frame rather than the universal retainer) and thus are not described in the same way as the classic retainer-based approach.