How does increasing water pressure affect air trapped in a tooth cavity during descent, causing barodontalgia?

The trapped air is compressed, leading to a sharp, painful sensation.

The mechanism behind barodontalgia during descent is rooted in Boyle's Law applied to the confined space within a tooth. As the scuba diver descends, the surrounding water pressure increases significantly. If there is any existing cavity, a microscopic gap beneath an old filling, or any compromised seal in the tooth structure, air or water vapor trapped within this internal space becomes subjected to this increasing external pressure. Since the air cannot escape or equalize easily, it is compressed, exerting inward force on the sensitive pulp chamber, which manifests as a sharp, painful sensation directly related to the pressure differential across the defective restoration.