Dental Fillings Explained: Materials, Process, and Aftercare

Hearing "you have a cavity" during a checkup is one of the most common pieces of dental news there is, and also one of the least scary once you understand what actually happens next. A filling is the most routine repair in dentistry. Most people have at least one, and the procedure itself is usually finished in under an hour with just a bit of numbness afterward.

Still, walking in without knowing what to expect, or what material is best for your situation, can make a simple visit feel more stressful than it needs to be. Here's what's actually going on.

Why you need a filling in the first place

Cavities start when bacteria in plaque feed on sugars and starches left on your teeth and produce acid as a byproduct. That acid slowly dissolves the minerals in enamel, and if it's not caught early, it eats a literal hole into the tooth. That hole is the cavity.

A filling does two things at once: it removes the decayed, softened tissue (which would otherwise keep spreading), and it fills the resulting space with a durable material that restores the tooth's shape, strength, and function. Left untreated, a small cavity keeps growing until it reaches the nerve, at which point a simple filling is no longer enough and you're looking at a root canal or worse.

This is really the core reason dentists push for regular checkups: catching a cavity while it's small means a small, cheap, quick filling instead of a much bigger procedure later.

Filling materials compared

Not all fillings are made the same way, and the right choice depends on the location of the cavity, your budget, and how it needs to look.

Composite resin is the most commonly used material today. It's a tooth-colored resin that bonds directly to the tooth structure, which means the dentist can often preserve more of the natural tooth compared to older techniques. It blends in well cosmetically, which makes it the default choice for front teeth and anywhere visible.

Amalgam is the classic "silver filling," a mix of metals including silver, tin, and mercury bound in a stable alloy. It's been used for well over a century because it's extremely durable and relatively inexpensive. The tradeoff is that it's clearly visible as a dark or silver spot, so it's mostly used on back molars now rather than anywhere it would show.

Ceramic or porcelain fillings, sometimes placed as inlays or onlays, are strong, resist staining better than composite over time, and look very natural. They cost more and typically require two visits since they're often custom-made in a lab, but they hold up well for people who want a long-lasting, invisible repair.

Glass ionomer releases fluoride over time, which gives the surrounding tooth some extra cavity protection. It's not as strong as the other materials, so it's usually reserved for small cavities, baby teeth, or fillings placed right at the gumline where it won't take heavy chewing pressure.

Material	Appearance	Durability	Typical use	Relative cost
Composite resin	Tooth-colored	Good, 5-10+ years	Front teeth, visible areas	Moderate
Amalgam	Silver/dark	Excellent, 10-15+ years	Back molars	Lower
Ceramic/porcelain	Tooth-colored	Excellent, resists staining	Larger cavities, visible or hidden	Higher
Glass ionomer	Tooth-colored	Fair	Kids' teeth, near gumline	Lower to moderate

What actually happens during the procedure

The process is fairly standardized regardless of which material you choose.

1. Numbing. The dentist applies a local anesthetic to numb the tooth and surrounding gum. Most people feel a small pinch and then nothing for the rest of the appointment.
2. Removing the decay. Using a dental drill or, in some cases, a laser, the dentist removes the decayed portion of the tooth. This is the part that produces the noise many people associate with dental visits, but it shouldn't be painful once you're numb.
3. Cleaning and shaping the cavity. The remaining space is cleaned of bacteria and debris and shaped so the filling material will bond and sit properly.
4. Placing and curing the filling. For composite, the resin is applied in layers and hardened with a curing light between layers. Amalgam is packed in and left to harden on its own. Ceramic inlays are cemented into place, sometimes at a second visit.
5. Checking your bite. The dentist has you bite down on articulating paper to check that the filling isn't sitting too high, then polishes and adjusts as needed.

Most fillings take somewhere between 20 and 60 minutes depending on size and location. Numbness typically wears off within two to four hours.

What to expect right after

Mild sensitivity to hot, cold, or pressure for a few days is normal, especially with a deeper cavity. It should fade on its own; if sensitivity is sharp, lingers for more than a week or two, or gets worse rather than better, that's worth a call back to the office since it can sometimes mean the filling needs a small adjustment. Avoid chewing on the numb side until feeling returns, so you don't accidentally bite your cheek or tongue.

Making a filling last for years

Fillings are durable, but they aren't permanent, and how you treat your teeth afterward has a real effect on how long one lasts.

• Keep up consistent brushing and flossing. Decay can still form around the edges of an old filling if plaque builds up there, sometimes called recurrent decay.
• Limit sugary and starchy snacks, especially sipping on sugary drinks throughout the day, which keeps your mouth in an acidic state for longer.
• Avoid chewing ice, hard candy, or using your teeth as tools. These are some of the most common reasons a filling chips or cracks before its time.
• Keep up with regular checkups, so a dentist can catch a failing filling early, before it turns into a bigger repair.
• Wear a nightguard if you grind your teeth. Grinding puts repeated pressure on fillings that they weren't designed for daily, and it's one of the more preventable reasons fillings fail early.

How long do fillings actually last?

It varies by material and how well you take care of your teeth, but general ranges look like this: composite fillings often last 5 to 10 years or more, amalgam can last 10 to 15 years or longer, and ceramic fillings frequently outlast both. None of these numbers are guarantees in either direction. Someone who grinds their teeth heavily might need a composite filling replaced sooner, while someone with excellent hygiene might get well beyond the average out of any material.

What affects the cost of a filling

There's no single price that applies to everyone, since cost depends on several factors that vary case by case:

• Material. Amalgam tends to sit at the lower end, composite is typically a bit more, and ceramic fillings cost more still since they're often custom-made in a lab.
• Size and location. A small cavity caught early costs less to fill than a large one that involves more of the tooth's surface.
• Number of surfaces involved. Dentists often price fillings by how many sides of the tooth are affected, so a cavity that wraps around multiple surfaces costs more than one contained to a single spot.
• Where you live and the specific practice. Dental fees vary regionally and from office to office, sometimes significantly.
• Insurance coverage. Many dental insurance plans cover a meaningful portion of a basic filling, though coverage for higher-cost materials like ceramic is often more limited.

If cost is a concern, it's reasonable to ask the office for a written estimate before treatment and to ask whether a less expensive material would still be appropriate for that particular tooth. In nearly every case, treating a cavity while it's small is far less expensive than waiting until it requires a root canal or crown.

FAQ

Will getting a filling hurt? The numbing shot involves a brief pinch, but the actual filling procedure shouldn't hurt once the area is numb. Some pressure or vibration from the drill is normal to feel, just not pain.

Can I eat right after getting a filling? It's best to wait until the numbness wears off, usually two to four hours, so you don't accidentally bite your cheek or tongue without realizing it. For composite fillings, most dentists say you can eat normally right away since the material is fully hardened by the curing light before you leave.

Why does my dentist recommend replacing an old amalgam filling? Usually it's because the filling has cracked, is leaking around the edges, or the tooth underneath has developed new decay, not because amalgam itself is inherently unsafe. If a dentist raises a cosmetic reason instead, like wanting a tooth-colored option, that's a personal choice rather than a necessity.

Is a cavity always painful before you notice it? No, that's exactly why regular checkups matter. Many cavities cause no pain at all in the early stages and are only caught on an X-ray or during an exam, well before they'd ever hurt.

What happens if I just ignore a small cavity? It will keep growing since the decay process doesn't reverse on its own. What starts as a filling can turn into a root canal or a crown if it's left long enough to reach the nerve, so it's almost always cheaper and simpler to treat it early.

The bottom line

Fillings are about as routine as dental work gets, and modern materials mean they can be strong, comfortable, and in most cases nearly invisible. The real lesson is timing: a small cavity caught early means a quick, simple filling, while the same cavity left alone for a year or two can mean a root canal or crown instead. Regular checkups are what make the difference between the two.