Why is marginal leakage associated with polymerization shrinkage and a high thermal coefficient of expansion reduced?

The correct answer focuses on the concept of the luting layer being very thin, which plays a crucial role in reducing marginal leakage associated with polymerization shrinkage and a high thermal coefficient of expansion.

When a luting layer is thin, it minimizes the volume of material that can potentially contract or expand due to temperature changes and the effects of polymerization. A thin luting layer also allows for better seating of the prosthetic component onto the tooth structure, which helps to closely adapt the margins. This close adaptation is key in reducing gaps between the restoration and the tooth, thereby decreasing the likelihood of marginal leakage.

On the other hand, thicker luting layers are more prone to exhibit increased marginal leakage because they can provide more space for movement or alteration during the curing process or temperature fluctuations. Therefore, maintaining a thin luting layer is beneficial for achieving a better seal and enhancing the longevity of the dental restoration by minimizing the effects of shrinkage and thermal expansion.