Pulpal damage under restoration can be caused primarily by?

Pulpal damage under restoration is primarily caused by bacterial action due to the potential for microorganisms to invade the pulp chamber through caries or microleakage. When bacteria penetrate the restorative material and reach the pulp tissue, they can induce inflammatory processes, leading to pulpitis or necrosis. This invasion can occur as a result of inadequate sealing of the restoration, allowing bacteria from the oral cavity to access the dentinal tubules and subsequently the dental pulp.

While factors such as general heat, chemical irritants from restorative materials, and mechanical stress can also impact dental pulp health, it is the bacterial action that plays a crucial role in the most direct and significant form of pulpal damage leading to infection. This underlines the importance of proper sealing and hygiene in restorative dentistry to minimize the risk of bacterial infiltration and pulpal complications.