Why are metal fillings damaging to tooth structure?
Old-fashioned metal fillings are not bonded to the tooth like inlays and onlays. Metal fillings stay in the tooth only because they are tightly packed into the cavity, putting outward pressure on the tooth’s periphery. Also, when hot or cold foods are consumed, they expand and contract in response to temperature changes. This repeatedly changes the pressure on the tooth, weakening surrounding tooth structure and eventually breaking it. Porcelain fillings do not disturb healthy tooth structure, and because they are bonded to the tooth, they will not weaken or crack it over time.
