What do you call an occurrence of tooth decay?

The correct term for an occurrence of tooth decay is "caries." Caries refers to the decay or demineralization of tooth structure caused by the action of bacteria that produce acids from sugars in food. This process leads to the formation of cavities within the teeth, which can progress over time if not treated. The term "carious lesion" describes the visible result of caries, which is indeed a specific manifestation of decay, but it does not encompass the larger concept of tooth decay itself.

Alternatively, while "dental cavity" is commonly used to refer to the holes or structural damage in the teeth resulting from caries, it is more a result of tooth decay rather than a term that encompasses all aspects of the decay process. "Tooth erosion" refers to the loss of tooth structure due to non-bacterial factors, such as acids from food or drinks, rather than the bacterial processes involved in caries. Therefore, "caries" is the most accurate term for an occurrence of tooth decay.