What is a common reason for pain in teeth filled with deep amalgam when exposed to hot or cold?

Pain in teeth filled with deep amalgam when exposed to temperature changes, such as hot or cold substances, is often attributed to the characteristics of the deep amalgam filling itself. When a tooth has extensive decay removed, it often requires a deep filling that can come close to the nerve (pulp) of the tooth. This proximity can leave the nerve more sensitive to thermal stimuli.

The sealing ability of deep amalgam may also play a role in the pain experienced. If the amalgam does not completely seal the cavity, fluids can penetrate through microleakage at the interface between the tooth structure and the filling, leading to irritation of the pulp when temperature changes occur. This sensitivity is a manifestation of the tooth's response to stimuli due to its anatomy and the materials used in the restoration.

Additionally, it’s important to note that while poor dental hygiene and tooth decay progression can contribute to dental pain, they do not specifically explain the sensitivity related to thermal exposure in a tooth that has already been treated with a deep amalgam filling. Allergic reactions to amalgam are relatively rare and less likely to cause sensitivity due to temperature changes. Therefore, a deep amalgam filling is the most direct cause of temperature-related pain in this context.