Why Choose Composite Resin Fillings Over Amalgam

Dental fillings date back thousands of years, with ancient civilizations using materials like beeswax and resin to repair teeth

Today, the choices for dental filling material are more diverse than ever. Teeth can be filled with various biocompatible materials, such as gold, porcelain, amalgam, or tooth-colored plastic called composite resin fillings.

For this discussion, we’ll focus on two highly compared options: composite resin and amalgam fillings. This article will answer the many questions surrounding these two dental filling materials. 

Most importantly, this article focuses on why composite resin fillings are a better alternative than amalgam. Keep reading to learn more.

Understanding composite resin fillings

Composite fillings are made of a mixture of resin and ceramic particles that can be customized to match the color and shape of the natural tooth. The dentist places composite fillings in layers, each layer being hardened by a special light. The dentist then shapes and polishes the filling to fit the tooth and restore its function and appearance.

Composite resin fillings are considered better than amalgam fillings in most cases, especially for front teeth or visible areas of the mouth, because they offer two main advantages:

Aesthetics and natural appearance

They can be matched to the color and shape of the natural tooth and blend in seamlessly with the surrounding teeth. Amalgam fillings, on the other hand, are silver or gray in color and can create a noticeable contrast with the natural teeth, especially when they darken over time.

Its aesthetic benefits account for a quarter of the total dental fillings market. As per a 2023 market report, the composite resin category held a market share of approximately 35% in the field of tooth-filling materials during 2022.

The report also projected that the demand for composite resin fillings would increase in the coming years, especially in Asia, due to the rising awareness of oral health and aesthetics.

Comparison of dental fillings: Amalgam filling on the left and composite resin filling on the right.

On the left, the classic amalgam filling; on the right, the modern marvel of composite resin.

Bonding and protection

Composite fillings offer notable durability and fracture resistance for small to medium-sized cavities. They effectively adhere to the tooth structure, forming a secure seal that safeguards against additional decay or breakage.

Moreover, they preserve more of your natural tooth as they require less removal of healthy tissue than amalgam fillings. Amalgam does not bond to the tooth and can create gaps or cracks that allow bacteria and food particles to enter and cause more damage. It also requires more drilling and removal of healthy tooth structure, weakening the tooth and making it more prone to breaking.

While there are pros to choosing composite resin fillings, it’s equally important to consider the following cons:

Higher cost

Composite fillings are more expensive than amalgam fillings as they require more time and skill to place and may not be covered by some insurance plans. 

The price of your filling hinges on two primary factors: the tooth's shape and location. In California, composite fillings could range from $250 to $450 for one or multiple tooth surfaces for those without dental insurance.

On the other hand, the out-of-network cost of tooth-colored filling for a single front tooth can range from $232 - $360. A tooth-colored filling for a back tooth can cost around $253-$365.

Disclaimer: These numbers are based on Delta Dental’s Cost Estimator. Prices may still vary depending on your location and your dental insurance plan. Discussing your treatment's cost with your insurance provider or dentist is still essential.

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Shorter lifespan

The average lifespan of composite resin fillings ranges from 5 to 10 years, with some studies suggesting that they can last longer if the fillings are smaller and well-maintained. This is relatively shorter than amalgam, which can last up to 15 years.

So, it’s essential to understand how long your fillings are to last and can influence their lifespan. 

According to a systematic review and meta-analysis of the longevity of posterior composite resin restorations, the following variables significantly influenced the survival of posterior composite resin fillings:

  • Patient age - Older patients had lower failure rates than younger patients.
  • Caries-risk status - High-risk patients had higher failure rates than low-risk patients.
  • Number of restored surfaces - Restorations with more surfaces had higher failure rates than restorations with fewer surfaces.
  • Resin composite material - Some resin composite materials performed better than others, depending on the study and the follow-up period.
  • Use of glass-ionomer cement as base/liner - Restorations with glass-ionomer cement as base/liner had lower failure rates than restorations without it.

On the other hand, the same study suggested that the following variables did not significantly influence the survival of posterior resin composite restorations:

  • Patient gender
  • Jaw (upper or lower)
  • Adhesive material

Composite resin fillings look more natural and protect against decay, but they cost more and may not last as long, with factors like age and material choice playing a role. Now, let's shift our focus to understanding amalgam fillings.

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Things you need to know about amalgam fillings

In some cases, amalgam fillings might make more sense than composite ones, depending on the patient's needs and preferences. Things like where the tooth is, what the patient likes, and what's cost-effective all play a role.

Dental amalgam combines metals comprising liquid elemental mercury and powdered silver, tin, and copper alloy. By weight, about 50% of dental amalgam is elemental mercury. The unique chemical properties of elemental mercury enable it to interact with and unite the silver/copper/tin alloy particles, creating an amalgam.

Although these fillings are commonly called "silver fillings" due to their silver-like appearance, it's worth noting that this term is not ideal for accurately describing amalgam composition.

Placing dental amalgam typically involves the following steps: 

First, the dentist drills the tooth to remove the decay and prepares the tooth cavity to accommodate the amalgam filling. 

Then, taking appropriate safety precautions, the dentist combines the powdered alloy, typically encapsulated, with liquid mercury to create an amalgam putty. This softened amalgam putty is carefully inserted into the prepared cavity and molded to fit. 

Over a short period, it undergoes rapid hardening, forming a solid filling within the tooth.

Are amalgam fillings still used nowadays?

Although amalgam fillings have been around dentistry for about 150 years, their use in dental restoration has declined. These fillings’ waning popularity can be attributed to safety concerns and the increasing demand for more advanced and aesthetically pleasing alternatives. 

However, the FDA has examined scientific research and found no evidence linking health problems to amalgam fillings. They have declared dental amalgam fillings are safe for adults and children aged six and above. Additionally, there is limited evidence indicating that these fillings do not harm the fetus during pregnancy.

Some dentists who still use amalgam fillings often highlight how durable and safe they are compared to resin composites. Surprisingly, this cost-effective dental procedure can last much longer than other options, sometimes even double the time.

Is it possible to replace amalgam fillings with composite resin?

The FDA advises against removing or replacing your amalgam fillings, especially if they are in good shape with no decay beneath them. Doing so unnecessarily results in the loss of healthy tooth structure and temporary exposure to increased mercury vapor during the removal process. 

Suppose you are sensitive or allergic to mercury, neurological or kidney issues, or other lingering health conditions. In that case, discussing the need for removal and replacement with your dentist or physician is advisable.

Final Thoughts

Regardless of the safety concerns associated with amalgam fillings, there's no hiding the fact that they do offer inarguable benefits. Since its placement isn't technique-sensitive, the process can be short and thus cheaper. Amalgam also has a superior lifetime than composite resin. Its affordability, widespread popularity, and convenience make it a magnet for individuals with limited financial resources.

But why do we believe composite resin fillings still win the battle between the two restorative procedures?

Our answer is simple:

Although composite fillings may come with a higher initial cost than amalgam, their attractive appearance, tooth preservation, and patient satisfaction often make them a valuable choice for those who want a natural-looking and less invasive dental repair.

So, consider our thoughts above if you feel it’s unreasonable to pay extra bucks to get rid of a small crack on a tooth. But if you still struggle to figure things out, we at United Dental Care in Culver City, CA, will help you make an informed decision. 

Book a free consultation now to learn more about our dental restoration services.

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