Final answer:
Percolation in dentistry is the movement of fluids and bacteria through gaps between a tooth and its filling, potentially causing dental health issues.
Step-by-step explanation:
Percolation in the context of dentistry refers to the movement of fluids and bacteria through micro-gaps between a tooth and its restorative filling material. When the seal between the tooth and the restorative material is not perfect, the ingress of bacteria and oral fluids can occur, potentially leading to recurrent caries, staining, and pulpal irritation. In other words, percolation is the process that allows external substances to seep through the interface of a tooth and its filling, which can compromise dental health and the longevity of the filling.