Five main materials handle most cavity fillings today: composite resin, dental amalgam, glass ionomer, porcelain (ceramic), and gold alloy. Composite resin and amalgam handle the majority of routine cases, while glass ionomer, porcelain, and gold earn their place in specific situations where appearance, fluoride release, or maximum durability matter more. The right pick depends on which tooth is affected, how much chewing force it absorbs, what the cavity looks like, and what you can budget for the visit.
This walkthrough breaks down the five filling materials most commonly used today, walks through the procedure step by step, and weighs how each option holds up in durability, appearance, and cost.
The Main Filling Materials Dentists Use Today
Walk into almost any US dental practice and you’ll encounter five distinct filling families. Each one solves a slightly different problem, and each one carries its own set of tradeoffs in cost, appearance, longevity, and how much healthy tooth structure the dentist has to remove.
Composite Resin
A tooth-colored blend of plastic and fine glass particles, composite resin bonds directly to your enamel. It dominates most general practices today because it can be shaded to match surrounding teeth so closely that the filled area becomes nearly invisible. A typical filling runs about 20 to 40 minutes per tooth and requires only a small amount of drilling, since the adhesive technology holds the material in place without undercutting the cavity.
The downside is wear: composite tends to chip or stain a bit faster than metal on the chewing surfaces of back teeth, where bite forces can exceed 200 pounds per square inch. It’s still the most-used direct filling material in the country, and a well-placed composite routinely lasts 5 to 10 years.
Dental Amalgam
The familiar silver filling is an alloy of silver, tin, copper, and mercury that American dentists have placed for more than 150 years. Amalgam is tough, inexpensive, and tolerant of less-than-perfect moisture control during placement, which is why it remains common for back molars and for patients on tight budgets. It typically outlasts composite in high-stress areas by several years.
The tradeoffs are visible: the gray color and the small but real mercury content make amalgam less popular for front teeth. Most practices now place amalgam only when the patient asks for it, when the cavity sits deep below the gumline, or when cost is the deciding factor.
Glass Ionomer
A self-adhesive cement, glass ionomer forms from acrylic acid and a silicate glass powder. Its standout feature is fluoride release: the material slowly gives off small amounts of fluoride into the surrounding tooth, which can help shield nearby enamel from future decay. It bonds well to dentin (the softer layer beneath enamel) and works in moist environments, so dentists often reach for it near the gumline, in children’s baby teeth, or as a temporary sealant.
The tradeoff is strength. Glass ionomer wears down faster than composite or amalgam, so it’s reserved for low-stress spots where appearance and chemical protection matter more than raw durability.
Porcelain (Ceramic) Inlays and Onlays
Porcelain restorations are lab-crafted pieces, often made through CAD/CAM milling or 3D printing, that fit into or over a prepared tooth like a custom puzzle piece. Because they’re milled from a single block of ceramic and bonded with high-strength adhesive, they resist staining better than composite and can last 10 to 15 years or longer. Porcelain costs more than other direct fillings because the lab step adds time.
Most porcelain inlays and onlays require two visits unless the office has an in-house milling unit. The result is a restoration that looks like natural enamel and handles bite forces almost as well as gold.
Gold Alloy Fillings
Custom-cast in a dental lab from gold, copper, and other metals, gold alloy restorations can last for decades. Gold is exceptionally biocompatible, gentle on opposing teeth, and famously durable. With proper care, a gold filling can last 20 years or more, often outlasting the tooth it’s placed in.
The barriers are visibility (it doesn’t blend in), the highest material cost of any option, and the need for two appointments plus a temporary filling while the lab works. Patients who choose gold usually do so for longevity on a back molar they want to keep for life.
Tip: Material choice matters most when the cavity sits in a high-stress or highly visible spot. Front teeth almost always look better with composite or porcelain. Back molars can handle tougher materials because the bite absorbs the stress.
What Happens During the Filling Procedure
The filling visit itself follows a predictable rhythm, and knowing the steps ahead of time tends to take a lot of the dread out of the chair. Most appointments for a single, uncomplicated cavity run 30 to 60 minutes from the first numbing shot to the final polish.
Numbing the Tooth and Surrounding Tissue
Your dentist starts with a local anesthetic, most commonly lidocaine with a tiny amount of epinephrine, injected near the tooth. Within two to five minutes, the area goes fully numb. You’ll still feel pressure and vibration during the procedure, but not sharp pain. For patients with severe anxiety, some offices offer nitrous oxide (laughing gas) or oral sedatives on top of the local anesthetic.
Removing the Decay
Once the tooth is numb, the dentist removes the softened, decayed tissue. The traditional tool is a high-speed dental drill with a diamond or carbide bur, but many offices now also use laser decay removal or air-abrasion for smaller cavities. Each approach targets the same goal: clean out compromised enamel and dentin while preserving as much healthy structure as possible.
Preparing the Surface for Bonding
After the decay is gone, the cavity is shaped and conditioned. For composite and glass ionomer, the dentist applies an etching gel (usually phosphoric acid) to open up microscopic pores in the enamel, then places a bonding agent that flows into those pores and cures hard under a blue LED light. For amalgam, the cavity is shaped with undercuts that lock the filling in mechanically, so no adhesive is needed.
Placing and Curing the Material
The chosen material goes in next, usually in thin layers rather than one big blob. Each layer of composite is hardened with the curing light for about 20 seconds. Amalgam is packed in increments and carved to shape while soft, then allowed to harden on its own over the next few hours. Glass ionomer sets through a chemical reaction once mixed, and porcelain or gold restorations are cemented into place with resin adhesive.
Shaping and Polishing
The final step is an occlusion check and polish. Your dentist asks you to bite down on articulating paper, a thin carbon sheet that marks high spots, then trims the filling until your bite feels even. A polished surface resists plaque buildup and feels smooth against your tongue. The appointment ends with a quick rinse and post-op instructions.
How Each Material Compares in Durability, Appearance, and Cost
Numbers make the tradeoffs easier to weigh than adjectives. The table below pulls together typical lifespans, average per-tooth material cost (before insurance), and how each option looks once placed. Costs reflect a wide US range and depend heavily on geography, dentist experience, and insurance coverage.
| Material | Typical Lifespan | Average Cost per Tooth | Appearance | Best For |
|---|---|---|---|---|
| Composite resin | 5–10 years | $150–$300 | Tooth-colored | Most front and side teeth |
| Dental amalgam | 10–15+ years | $100–$250 | Silver-gray | Back molars, tight budgets |
| Glass ionomer | ~5 years | $150–$300 | Tooth-colored (less polished) | Gumline cavities, baby teeth |
| Porcelain (inlay/onlay) | 10–15+ years | $500–$1,200 | Tooth-colored, stain-resistant | Large restorations, visible teeth |
| Gold alloy | 20+ years | $800–$2,500 | Gold metallic | Heavy bite, longevity priority |
Composite and amalgam together account for roughly 80% of fillings placed in US general practices, with the balance split among glass ionomer, porcelain, and gold. The cost numbers above include the dentist’s fee and the material itself but not the diagnostic exam or X-rays, which can add $50 to $200 to the visit.
To judge true long-term value, divide the per-tooth cost by the expected years of service. Gold at $1,500 lasting 25 years works out to about $60 a year, often less than a composite that costs $200 and needs replacement twice in the same span.
That lifetime math gets sharper once you weigh it against where in your mouth each material actually performs best.
Matching the Right Filling to the Right Tooth
Material selection isn’t a free-for-all. The tooth’s location, the size of the cavity, and the conditions under which the filling has to set all push the decision in specific directions. A few general rules-of-thumb cover most cases.
Front Teeth and Visible Areas
Composite resin wins almost every time for front teeth. It bonds to enamel with enough strength for normal biting and can be layered in shades that disappear into your smile. Porcelain is the upgrade choice when the cavity is large or when you want the longest-lasting aesthetic result.
Back Molars Under Heavy Chewing Pressure
Amalgam and gold shine here because they handle repeated bite forces without chipping or wearing down. A composite filling on a back molar can work fine, but it may need replacement sooner if you grind your teeth or chew ice regularly. For root-cavity fillings on molars, glass ionomer is often the better pick because of its fluoride release.
Cavities Near the Gumline or in Children
Glass ionomer is the go-to because it releases fluoride that protects the surrounding tooth structure and tolerates the moisture that’s hard to control near the gum. Pediatric dentists also use it as a temporary filling in baby teeth that will fall out before any wear becomes a problem.
Very Large Decay
When more than half the tooth is gone, a direct filling often fails no matter which material you choose. The better long-term answer is usually an inlay, onlay, or full crown, where the lab-made restoration covers the entire chewing surface and protects the remaining walls from cracking. Catching a failing filling early is what keeps you out of the crown and root canal chair later.
Even the best-matched filling can raise questions, and chief among them is what those materials actually do inside your body.
The Mercury Question and Other Safety Concerns
Few dental topics stir up as much worry as mercury in amalgam. The fear is understandable, even if the science doesn’t back it up. Here’s where the consensus currently stands.
What the FDA and ADA Say
Amalgam releases a tiny amount of mercury vapor over time as the filling wears, but the levels fall far below the thresholds associated with health effects in adults and children over six. That conclusion comes from decades of review by the American Dental Association’s Council on Scientific Affairs and was reaffirmed by the U.S. Food and Drug Administration in a 2020 statement that has not been reversed since.
Who Should Talk Through Alternatives
Patients with a known mercury allergy, impaired kidney function, or who are pregnant or planning pregnancy often choose composite, glass ionomer, or porcelain as a precaution. These alternatives are equally functional for most cavities, and most mercury-free practices recommend them routinely. The conversation matters more than the specific material in these cases.
When Removing a Serviceable Amalgam Makes Sense
Replacing an amalgam filling solely to eliminate mercury is generally not recommended by professional bodies, because every replacement removes a thin layer of healthy tooth and shortens the tooth’s lifespan. Replacement makes sense when the filling is cracked, leaking, or showing new decay around its edges. Your dentist can confirm which scenario applies with a close clinical exam and a bitewing X-ray.
Symptoms like sensitivity or a rough edge are easy to misread at home, so knowing which signs actually warrant a call matters.
Warning: All five filling materials are FDA-approved and considered biocompatible. Adverse reactions are rare across the board, but if you’ve had unexplained sensitivity or mouth sores after a previous filling, flag it before the next visit.
Caring for a New Filling and Knowing When to Call the Dentist
Fillings don’t fail all at once. They warn you first with sensitivity, sharp edges, or changes in your bite. Catching those warnings early turns a $150 replacement into a simple adjustment and saves the tooth from a more invasive fix later.
What’s Normal After the Procedure
Mild sensitivity to cold, heat, or pressure is common for one to two weeks after a new filling, especially with deep cavities that came close to the nerve. The sensation usually fades on its own as the tooth settles. Composite fillings in particular can feel slightly rough against your tongue for the first day until the polish wears in.
Signs That Something Needs Attention
Sharp pain when biting down, lingering throbbing that wakes you up at night, or a sudden height change where the filling feels taller than the surrounding teeth all warrant a quick call. The same goes for cracks, chips, dark lines around the filling edges, or a gritty feeling that won’t brush away. Each of those is a sign the restoration may be failing and needs evaluation before the underlying tooth cracks.
Daily Habits That Extend Filling Life
Brush twice a day with fluoride toothpaste, floss once daily, and keep up with professional cleanings every six months. Nightly grinders should ask about a custom occlusal guard, a hard-acrylic mouthguard that absorbs bite force and protects both natural teeth and restorations from premature wear.
- Mild sensitivity lasting one to two weeks is normal and usually fades.
- Sharp bite pain or a filling that feels high needs a quick adjustment.
- Cracks or dark margins around the edge signal possible failure.
- Daily brushing and flossing extend the life of every filling type.
- Night grinding warrants a custom guard to protect both teeth and restorations.
Making a Confident Decision With Your Dentist
Walk into the visit with a short mental checklist and the conversation gets easier. Cavity location, bite pressure, visibility, and budget each nudge the decision in a specific direction, and your dentist can weigh those factors against your specific tooth in a way no online article can.
Ask which materials your dentist has the most experience placing, because technique influences longevity as much as the material itself. Request a written treatment plan with the procedure codes your insurance uses, so out-of-pocket costs are clear before any drilling starts. And trust that there is rarely one universally right answer; the best filling is the one matched to the tooth, the budget, and your priorities for the next decade.
Final Thoughts
The filling material sitting in your tooth is a small choice with long-term consequences for both appearance and durability. Composite and amalgam handle the majority of routine cases well, while glass ionomer, porcelain, and gold earn their place in specific situations. The smartest move you can make is to ask informed questions in the chair, weigh cost against expected lifespan, and choose the material that fits both the tooth and your priorities.
FAQ
How long does a typical filling last?
Composite fillings last 5 to 10 years on average, amalgam lasts 10 to 15 years or longer, glass ionomer lasts about 5 years, porcelain lasts 10 to 15 years, and gold can last 20 years or more with proper care. Lifespan depends heavily on cavity size, bite forces, and oral hygiene habits.
Are silver amalgam fillings safe?
Yes. The FDA and American Dental Association both classify amalgam as safe for adults and children over age six. The mercury in amalgam is bound in a stable alloy and releases only trace amounts of vapor, far below levels associated with health effects.
Which filling material looks the most natural?
Composite resin and porcelain are the most natural-looking options. Composite can be shaded in a single visit to match your surrounding enamel, while porcelain is lab-crafted for the closest possible match and resists staining better over time.
Does getting a filling hurt?
Modern fillings are largely pain-free. A local anesthetic numbs the tooth and surrounding tissue, so you’ll feel pressure and vibration during drilling but not sharp pain. Mild sensitivity for one to two weeks afterward is common and usually resolves on its own.
Can I replace my silver fillings with white ones?
Yes, if the amalgam filling is cracked, leaking, or showing new decay around its edges. Replacing a serviceable filling solely to change materials removes a thin layer of healthy tooth each time and shortens the tooth’s lifespan, so most dentists recommend replacement only when the old filling is failing.
What is the cheapest filling material?
Dental amalgam is the lowest-cost option in most US fee schedules, typically $100 to $250 per tooth. Composite and glass ionomer run slightly higher, while porcelain and gold are the most expensive because they require lab fabrication and multiple visits.
