When you need a filling, your dentist probably mentions several options. You might be confused about what the difference really is between silver amalgam, tooth-colored composite, and other materials. Let's break down how these restorations actually compare so you can understand what's best for your situation.
Amalgam: The Old Reliable Choice
Amalgam (those silver fillings) have been around for over 150 years, and they have an impressive track record. Learning more about Complete Guide to Dental Exams and Cleanings can help you understand this better. Studies show they last an average of 15+ years—that's significantly longer than newer composite materials. About 90% of amalgam fillings are still holding strong at 10 years, and many last 20 years or more. Amalgam is tough, withstands chewing forces really well, and doesn't require as much precise technique as composite does.
The worry many people have about amalgam is mercury. Here's the science: the mercury in set amalgam is chemically locked into the material and stays put. The amount you're exposed to is negligible—about 1-5 micrograms daily from an amalgam filling, which is way less than what you get from eating certain foods. The American Dental Association and FDA have both confirmed that amalgam is safe for non-pregnant people who aren't allergic to it.
Composite Resin: Beautiful but Not as Durable
Composite resins are the tooth-colored fillings everyone wants because they look natural. And they do look great. But they don't last as long as amalgam. Studies show composite resins have about 50% survival rate at 10 years, compared to 75-90% for amalgam. On average, you're looking at 7-12 years before composite needs replacing.
Why don't composites last as long? When composite hardens, it shrinks slightly (about 4-7% of its volume), which creates stress at the interface between the filling and your tooth. This shrinkage and stress can lead to tiny gaps forming over time, which is how bacteria get under the filling and cause decay again. Even with perfect technique, composite restorations fail at a higher rate than amalgam.
The Mercury Safety Question
You've probably heard something about silver fillings being dangerous. The science is clear: the mercury in set amalgam isn't going anywhere. Your daily exposure from an amalgam filling is about 1% of the mercury you get from other sources like food. For reference, the occupational safety limit for mercury exposure is 10,000-25,000 micrograms daily—your filling exposes you to just a few micrograms.
That said, if you're very concerned or allergic to mercury, composite fillings are absolutely an option. They're just not as durable, so be prepared that you might need them replaced more often.
Glass Ionomer: Limited but Useful
Glass ionomer is a material that releases fluoride, which helps prevent decay. Learning more about Composite Resin Durability: Longevity and Clinical can help you understand this better. It's decent for cervical cavities (cavities near your gum line) or specific situations where you need the fluoride benefit. However, it's not strong enough for cavities where you do a lot of chewing. Glass ionomer fillings typically last 8-10 years and are less common now that composite has improved.
Ceramic Restorations: The Premium Option
For bigger cavities, ceramic inlays and onlays are an option. These are made in a lab to fit your tooth perfectly. They look fantastic and last as long as amalgam (90-95% still intact at 10 years). The downside is cost—they're about 3-5 times more expensive than composite fillings and require two appointments instead of one. They're worth considering for large cavities that are highly visible.
How to Prevent Cavities Around Fillings
Here's something many people don't realize: the material itself isn't the main thing that determines whether you get decay around a filling. How your dentist places it and how well you care for your teeth matters much more. Cavities around filling edges (called secondary caries) happen when the seal between the filling and tooth breaks down, letting bacteria in.
Keeping the edges of your fillings sealed is critical. Your dentist should have placed your filling so the edges blend perfectly with your tooth, with no overhanging material. If you take care of your teeth with good brushing, flossing, and reducing sugar intake, your fillings—whether composite or amalgam—will last much longer.
Making Your Decision
For back teeth that are out of sight: amalgam is the most durable and cost-effective choice. You'll probably get 15-20 years out of it, and if cost matters, it's cheaper than other options.
For front teeth or visible areas: composite makes sense even though it won't last as long. Most people choose appearance over longevity in these spots.
For very large cavities: ceramic inlays or onlays last the longest and look beautiful, but they're expensive.
For people concerned about anything containing mercury: composite is your option, just understand you'll likely need replacements more often.
The Real Lifespan Question
One thing to understand: no filling is truly "permanent." Even the best amalgam eventually needs replacing. Plan for amalgam to last 15-20 years, composite 7-12 years, and glass ionomer about 8-10 years. When your dentist recommends replacing an old filling, it's usually because the seal is breaking down, not because the material has simply worn out.
Every patient's situation is unique—always consult your dentist before making treatment decisions.Conclusion
Amalgam is more durable and lasts longer, while composite is more esthetically pleasing but typically needs replacement sooner. Both are safe—the choice depends on location, budget, and your personal preferences. The most important factor isn't the material; it's how well your dentist places it and how well you care for your teeth afterward.
> Key Takeaway: When you need a filling, your dentist probably mentions several options.