Dental fillings are restorative treatments designed to repair teeth damaged by decay. While durable, they are not permanent fixtures and have a finite lifespan. Fillings replace lost tooth structure but, like any material subjected to the constant stress of chewing and the harsh environment of the mouth, they eventually need replacement. This need is driven by the physical breakdown of the material or the surrounding tooth structure, not because the filling dissolves or fades away.
What Dental Fillings Are Made Of
Modern dentistry primarily utilizes two types of materials for direct fillings, offering a distinct balance of strength and aesthetics. Dental amalgam, often called silver fillings, is a robust metal alloy composed mainly of silver, tin, copper, and liquid mercury. This combination hardens into a strong, wear-resistant restoration favored for its durability in back teeth that sustain heavy chewing forces.
Composite resin, known as tooth-colored fillings, offers a more discreet option that blends seamlessly with the natural tooth. This material is a mixture of an acrylic resin matrix and fine filler particles, such as glass or quartz. Composite fillings are chemically bonded directly to the tooth structure, which helps support the remaining tooth.
Expected Lifespan by Material Type
The life expectancy of a dental filling depends heavily on the material used, its location in the mouth, and the patient’s habits. Amalgam fillings are known for their longevity and typically last between 10 and 15 years. Their ability to withstand significant occlusal (chewing) forces makes them a reliable choice for large restorations on molars.
Composite resin fillings, while aesthetically superior, generally have a shorter average lifespan than amalgam, usually lasting five to ten years. Fillings placed in areas of the mouth that experience less mechanical stress, such as the front teeth, often last longer than those on the chewing surfaces of molars. The size of the filling also influences durability, as larger restorations are exposed to greater forces and tend to fail more quickly.
Why Fillings Need Replacement
Fillings require replacement when the seal or the material itself fails, compromising the health of the restored tooth. The most common reason for failure is secondary decay, also known as recurrent decay, which forms around the margins of the existing filling. This occurs when the seal between the filling and the tooth weakens, creating a microscopic gap (microleakage) that allows bacteria and food debris to infiltrate. The bacteria then decay the tooth structure underneath or adjacent to the restoration.
Another significant issue is the physical failure of the restoration material or the surrounding tooth. Large amalgam fillings, for example, can place stress on the remaining tooth walls, leading to a fracture of the tooth structure itself. The filling material can also chip or crack due to the constant, high-pressure forces of chewing. This fracture creates new entry points for bacteria, necessitating replacement and potentially a more extensive restoration like a crown.
Gradual wear and tear, or occlusal wear, is also a factor, particularly with composite resins. Over many years of chewing, grinding, or clenching, the material on the biting surface can slowly erode. This wear changes the tooth’s shape and function, which can lead to sensitivity or an improper bite alignment, signaling the need for intervention.
Practical Steps to Prevent Premature Failure
While all fillings have a limited life, specific actions can maximize their useful lifespan. Maintaining excellent oral hygiene is fundamental, including brushing twice daily with fluoride toothpaste and flossing once a day. Flossing is particularly important for cleaning the areas around the filling margins, where bacteria commonly accumulate and initiate secondary decay.
Regular dental check-ups are crucial for the early detection of potential problems. Dentists can visually inspect the margins for signs of breakdown and use X-rays to check for decay forming underneath the filling, a condition that is often asymptomatic until severe.
Avoiding habits that place excessive stress on the teeth can also preserve the integrity of the filling. Refrain from chewing on very hard objects, such as ice or hard candies, and avoid using teeth as tools to open packages. Patients who grind their teeth (bruxism) should discuss wearing a custom nightguard with their dentist to mitigate destructive forces applied to their restorations during sleep.