A dental filling is a restorative material used to replace tooth structure lost due to decay or trauma. The procedure involves removing the decayed portion of the tooth and filling the void to restore the tooth’s shape and function. When a person has many restorations, it is natural to question whether the volume of material poses a risk to their health or the long-term integrity of their teeth. Concerns about multiple fillings primarily relate to the safety of the material used and the mechanical weakening of the tooth structure over time.
The Materials Debate: Amalgam vs. Composite
Anxiety regarding multiple fillings often centers on dental amalgam, commonly known as “silver fillings,” due to its elemental mercury content. Amalgam is a durable mixture of metals, approximately 50% of which is elemental mercury, blended with silver, tin, and copper. This material is highly valued for its exceptional durability and longevity, often lasting 10 to 15 years or more, especially in high-stress areas like molars.
Composite resin fillings are tooth-colored materials made from a mixture of plastic and fine glass particles. They are aesthetically preferred as they blend seamlessly with the natural tooth, but they generally have a shorter average lifespan, often ranging from five to ten years. Composite resins bond directly to the tooth structure, allowing for less removal of healthy tooth material during placement compared to amalgam.
Concerns about the small amounts of mercury vapor released from amalgam fillings have been studied extensively. The U.S. Food and Drug Administration (FDA) has concluded that amalgam is generally safe for the majority of the population aged six and older. However, the FDA recommends that certain high-risk groups should consider non-amalgam alternatives like composite resins.
- Pregnant women
- Nursing women
- Children
- People with neurological disease or impaired kidney function
The FDA also advises against removing existing, intact amalgam fillings unless medically necessary, such as due to an allergy. Removing a stable filling can result in unnecessary loss of healthy tooth structure. It also temporarily exposes the patient to an increase in mercury vapor during the removal process.
Structural Integrity and Tooth Longevity
The physical presence of any filling means that a portion of the natural tooth has been removed, which compromises its innate strength. When a cavity is large or covers multiple surfaces, the resulting filling is extensive, significantly weakening the remaining tooth structure. Heavily restored teeth are at an increased risk for mechanical failure.
A common consequence of large fillings is the weakening of the tooth’s cusps, the pointed chewing surfaces. The forces of biting and chewing can cause stress fractures or cracks to develop in the compromised cusps, potentially leading to a complete tooth fracture. This kind of failure often necessitates a more extensive intervention, such as a full-coverage restoration like a crown, to hold the remaining tooth together.
Another major concern is the development of recurrent decay, also called secondary caries, which occurs at the margin where the filling meets the natural tooth. Over time, the seal between the filling and the tooth can degrade, creating microscopic gaps. These gaps allow bacteria and food debris to seep underneath the restoration. This hidden decay can progress undetected until it causes pain or is discovered during a dental examination, often requiring the replacement of the existing filling with an even larger one.
Understanding the Causes of Extensive Decay
Having numerous fillings is less a problem with the restorations themselves and more an indication of a systemic issue that led to widespread decay. The development of cavities, known as dental caries, occurs when acid produced by oral bacteria erodes the tooth enamel. These bacteria thrive on simple sugars and carbohydrates, which are their primary energy source.
A diet high in sugary or acidic foods and beverages creates an environment where decay-causing bacteria flourish. Poor oral hygiene, such as infrequent brushing and flossing, allows plaque to accumulate, accelerating this acid production. Other factors that reduce the protective effects of saliva also significantly increase the risk of decay.
Risk Factors for Decay
Factors that reduce saliva include certain medications like psychostimulants or antidepressants, or medical conditions like dry mouth (xerostomia). Genetic predisposition can also influence the composition of tooth enamel and the oral microbiome, making some individuals naturally more susceptible to cavities. Furthermore, habits like teeth grinding (bruxism) can wear down tooth enamel and damage the margins of existing fillings. Addressing these underlying risk factors is crucial for halting the cycle of decay and preventing the need for future fillings.
Managing Heavily Restored Teeth
For individuals who already have many dental restorations, management focuses on protecting the existing work and preventing new issues. Routine dental check-ups and x-rays are necessary to monitor the margins of the fillings, as these are the most vulnerable points for recurrent decay. Dentists can spot early signs of microleakage or marginal breakdown before the decay becomes extensive.
The lifespan of a filling is limited, and replacement may be recommended when a filling reaches the end of its viable life. Once a tooth has a very large filling that occupies a significant portion of the crown, the transition to a full-coverage crown becomes necessary to prevent fracture.
Maintaining meticulous oral hygiene, including daily flossing and brushing twice a day with fluoride toothpaste, is the most effective action to extend the life of existing fillings. Using a custom night guard can protect restorations from the destructive forces of clenching or grinding. By proactively monitoring restorations and controlling the factors that cause decay, patients can preserve their heavily restored teeth.