Which luting cement acts by being mechanically adhesive to the inner surface of a crown or bridge and the tooth?

Zinc phosphate cement acts by creating a mechanical bond between the restoration, such as a crown or bridge, and the prepared tooth structure. This cement is mixed to a dough-like consistency, allowing it to flow into the microscopic irregularities of the tooth surface. When it sets, it becomes rigid, forming a bond primarily based on its mechanical interlock rather than chemical adhesion.

This mechanical attachment is crucial in ensuring that the restoration remains securely in place over time, particularly under the forces of chewing and other functional stresses. While other luting cements may provide chemical bonding or other forms of adhesion, zinc phosphate's strength lies in its ability to grip the tooth structure through this mechanical mechanism, making it a reliable choice for cementing crowns and bridges.