What can cause post-operative sensitivity when restoring a class II with too large an increment of composite?

Choosing the option regarding under-curing, shrinkage, and improper condensing as the cause of post-operative sensitivity when restoring a class II with too large an increment of composite highlights important aspects of dental materials and techniques.

When a large increment of composite material is placed, it can lead to a few related issues. Under-curing implies that the material has not set to its full potential due to insufficient exposure to curing light. This can result in areas that remain soft or reactive, leading to sensitivity for the patient following the procedure.

Shrinkage occurs as the composite material hardens. An excessive increment can amplify this issue, as the material pulls away from the tooth structure during the curing process, potentially creating gaps or interface problems. This shrinkage can result in microleakage, which allows stimuli (such as temperature changes or sugary substances) to reach the pulp, causing discomfort or pain.

Improper condensing refers to how well the composite is packed into the cavity preparation. If the material is not adequately condensed, air pockets may form, or the material might not adapt well to the tooth structure. This lack of adaptation can contribute further to sensitivity issues post-operatively.

Overall, the correct answer emphasizes the importance of proper technique when working with composite materials and