Dental fillings are restorative materials placed into a tooth after decay is removed to restore its structure and function. They are not permanent and will inevitably wear down over time due to the daily stresses of the mouth. This gradual deterioration requires periodic monitoring and eventual replacement to protect the underlying tooth structure.
Causes of Filling Degradation
The hostile environment of the mouth constantly subjects dental fillings to mechanical and chemical breakdown. Physical stress, primarily from occlusal forces, is a major factor in a filling’s lifespan. Every act of chewing and biting transmits significant force through the tooth and directly onto the restoration, gradually causing microscopic fatigue and wear on the material’s surface.
This process is rapidly accelerated in individuals who clench or grind their teeth, a condition known as bruxism. Bruxism subjects fillings to non-stop, intense pressure cycles that can lead to chipping, fracturing, or premature wear of the filling material and the surrounding tooth structure. Fillings placed in high-stress areas, such as the chewing surfaces of molars, are particularly vulnerable to this mechanical breakdown.
Chemical and environmental factors also contribute to degradation. The constant presence of saliva, which fluctuates in acidity, can cause materials like composite resin to break down through hydrolysis.
The frequent ingestion of hot and cold foods and beverages causes the filling material and the natural tooth to expand and contract at different rates. This thermal cycling can weaken the seal between the filling and the tooth, creating microscopic gaps. This allows bacteria and fluids to leak in, leading to microleakage. Dietary acids can also chemically erode the surface of some filling materials over time.
Material Longevity and Wear Rates
Amalgam, often referred to as silver fillings, is a blend of metals that exhibits exceptional strength and durability under heavy chewing forces. These fillings are highly resistant to wear and can often last for 10 to 15 years, making them a reliable choice for posterior teeth.
Composite resin, the tooth-colored material, is favored for its aesthetic qualities but is generally less resistant to mechanical forces than amalgam. Composed of a plastic matrix mixed with glass filler particles, composite fillings typically have a shorter lifespan, often ranging from five to ten years. They are more susceptible to wear, staining from dark liquids, and their bond to the tooth structure can be more easily compromised over time.
For the longest-lasting restorations, gold and ceramic materials are often utilized. Gold fillings are custom-made and offer extreme durability, corrosion resistance, and the ability to withstand heavy bite forces, frequently lasting 20 years or more. Ceramic or porcelain fillings also provide excellent resistance to wear and staining, with a common lifespan of 10 to 15 years or longer.
Identifying and Addressing Worn Fillings
Increased sensitivity to hot or cold temperatures is a primary indicator of a failing filling, suggesting the protective seal may be compromised. A filling that has a noticeable sharp edge, a rough texture, or a visible crack or chip may also be structurally compromised.
Discoloration or darkening around the edges of the filling is a visual sign of marginal breakdown, indicating the seal is leaking and allowing bacteria to penetrate beneath the restoration. Pain when biting down or chewing suggests the filling has cracked, shifted, or that recurrent decay has developed. Ignoring these signs can lead to secondary decay, infection of the tooth’s pulp, or requiring a root canal procedure.
Good oral hygiene is important to extend the functional life of existing fillings, including regular brushing and flossing to prevent decay near the margins. Avoiding chewing on hard foods and wearing a custom-fitted nightguard if bruxism is present reduces mechanical wear.
During routine check-ups, the dentist assesses the margins and integrity of all existing restorations. If replacement is necessary, the old filling material is removed, the area is cleaned to eliminate secondary decay, and a new restoration is placed to re-seal the tooth.