For partial-coverage preparation, essential additional strengthening for the casting is provided by what?

In the context of partial-coverage crowns, the primary function of a luting agent is to provide an adhesive connection between the restoration and the tooth structure. While a luting agent may not directly strengthen the casting itself, it plays a critical role in ensuring the stability and retention of the restoration within the mouth. A well-chosen bonding material allows for the distribution of forces across the restoration and enhances overall durability against functional stresses.

Other factors, such as margin design and reductions in occlusal areas, influence how well these restorations function and how they interact with the existing tooth structure, but they do not provide the same reinforcing qualities as the luting agent. The additional groove and ledges can aid in retention and resistance form but do not contribute to the overall strength of the material in the same way that a suitable luting agent does in its role of securing the restoration.