How Do Fillings Work?

Tooth decay and cavities are some of the most common dental issues worldwide, and most of the time, the fix is a dental filling. But how do fillings actually work? In short, a filling replaces the part of your tooth that decay has destroyed. Your dentist removes the decay, then fills and seals the hole with a durable material that blocks bacteria from getting back in and restores the tooth’s shape so you can chew normally again. Tooth-colored fillings bond directly to the tooth, while metal fillings are held in by the shape of the prepared cavity.

At Dental Innovations in Oklahoma City, we place fillings every day. Here’s a closer look at how they work, what happens during the appointment, and how to make your fillings last.

Related Articles: How Long Do Fillings Last? | Why Do Fillings Fall Out?

Why a Cavity Needs a Filling

Dental caries, or tooth decay, happens when bacteria in your mouth feed on sugars and produce acids that break down tooth enamel. Over time, this creates a hole in the tooth, which is a cavity. If left untreated, a decayed tooth can cause infection, inflammation, pain, and even tooth loss.

Unlike skin or bone, tooth enamel can’t grow back. Very early decay that hasn’t broken through the enamel yet can sometimes be reversed with fluoride and good oral hygiene, but once a true hole forms, the tooth can’t repair itself. That’s where a filling comes in.

Dental filling procedures treat the tooth by removing the decay and filling the hole it leaves behind. This restores the remaining tooth structure, prevents bacteria from building up inside the tooth, and keeps the decay from spreading deeper toward the nerve.

How Fillings Stay in Your Tooth

A filling only works if it stays sealed tightly against the tooth. Depending on the material, fillings are held in place in one of three ways:

• Bonding (composite and other tooth-colored fillings): Your dentist applies a mild etching gel that creates a microscopic texture on the tooth, followed by a bonding agent. The filling material locks into that texture and is hardened with a special light, creating a strong, sealed bond with the tooth.
• Chemical bonding (glass ionomer fillings): These materials react with the tooth’s mineral surface and stick to it chemically. They also slowly release fluoride, which helps protect the surrounding tooth from new decay.
• Mechanical retention (amalgam fillings): Silver amalgam doesn’t stick to teeth. Instead, your dentist shapes the cavity so that it’s slightly wider at the bottom than the top, and the amalgam is packed in and hardens in place, locking itself in.

Larger restorations like gold or porcelain inlays and onlays are custom-made to fit the tooth and then cemented or bonded into place.

What Happens During a Filling Appointment

A typical filling takes 30 minutes to an hour and is usually completed in one visit. Larger cavities, or cavities in multiple teeth, may take longer or require more than one appointment. Here’s what you can expect:

1. Assessment

Your dentist will examine your teeth, often with X-rays, to determine the extent of the damage and confirm that a filling is the right treatment for your affected tooth.

2. Local Anesthesia

In most cases, a local anesthetic is used to numb the gums and area around your tooth so you don’t feel pain and are comfortable from start to finish. Learn more about what dentists use to numb your mouth for fillings.

3. Removing Decay

Your dentist will remove the decayed part of the tooth with a dental drill or, in some cases, a dental laser. Thanks to the anesthetic, this is a pain-free experience. Once all the decay is gone, the space is cleaned and shaped to hold the filling.

4. Placing the Filling

Next, your dentist places the chosen filling material into the prepared space. For tooth-colored composite fillings, the tooth is etched and coated with a bonding agent first, and the composite is placed in thin layers, with each layer hardened by a blue curing light. Amalgam fillings are packed into the space and harden on their own without a curing light.

5. Finishing and Checking Your Bite

Finally, your dentist shapes and polishes the filling so it looks natural and fits comfortably against the opposing teeth when you bite. You’ll be asked to bite on a thin marking paper so any high spots can be smoothed down.

Types of Filling Materials and How Each Works

There are several types of filling materials, each with unique characteristics. The right choice depends on the size and location of the cavity, your preferences, and cost. Your dentist can recommend the best type of filling for your specific needs.

Composite Resin Fillings

Composite fillings are the most common choice today because the material is tooth-colored and blends in with your natural teeth. Made from a mix of resin and fine glass-like particles, composite bonds directly to the tooth, so less healthy tooth structure needs to be removed. It’s not quite as durable as metal fillings in heavy-chewing areas, but it’s an ideal choice for small to medium-sized cavities and one of the most aesthetically pleasing options.

Silver Amalgam Fillings

Amalgam fillings (also called silver fillings) are made of a mix of silver, tin, copper, and mercury. They’re noticeable in the mouth because of their color, but they’re strong, durable, affordable, and long-lasting, so they’ve traditionally been used in back teeth that handle the most chewing pressure. The FDA recommends that certain higher-risk groups, such as pregnant women and young children, avoid amalgam when a suitable alternative is available.

Ceramic or Porcelain Fillings

Ceramic and porcelain fillings closely match the natural color of teeth and resist staining. They’re usually made as inlays or onlays, either in a dental lab or in a single visit with CEREC same-day technology, and are a strong, durable option for larger cavities.

Gold Fillings

Gold fillings are more expensive than other types, but they’re also extremely durable and resistant to wear. Dentists may recommend them for back teeth, where tooth decay treatment calls for a restoration that can handle heavy chewing forces.

Glass Ionomer Fillings

Glass ionomer fillings are made from a glass powder and an acrylic acid. They’re tooth-colored, bond chemically to the tooth, and release fluoride, adding another layer of protection against decay. Because they’re not as strong as other materials, they’re typically used for small fillings, cavities near the gumline, and baby teeth.

Resin Ionomer Fillings

Resin ionomer fillings are similar to glass ionomer but contain added resin, which makes them a bit stronger and better looking. Like glass ionomer, they release fluoride, making them a good tooth-colored option for low-pressure areas.

What a Filling Feels Like Afterward

It’s normal for your lip, tongue, and cheek to stay numb for a few hours after your appointment, so be careful not to bite them or eat very hot foods until the feeling returns.

Some sensitivity to cold, air, or pressure is also common for a few days to a couple of weeks as the tooth settles. If your bite feels high or uneven, or the sensitivity gets worse instead of better, call your dentist. A quick adjustment usually fixes it.

With composite fillings, you can typically eat as soon as the numbness wears off, since the material is fully hardened before you leave. Amalgam fillings take about 24 hours to reach full strength, so avoid chewing hard foods on that side for the first day.

How Long Do Fillings Last?

How long a filling lasts depends on the material, the size and location of the filling, and how well you care for your teeth. As a general guide, composite fillings often last 5 to 10 years, amalgam fillings 10 to 15 years or more, and gold or porcelain restorations 15 years or longer. For a full breakdown, see How Long Do Fillings Last?, and learn what causes early failure in Why Do Fillings Fall Out?

Tips for Maintaining Dental Fillings

Dental fillings work best when they are properly placed and well maintained. Here are some tips to protect your fillings and your overall oral health:

1. Practice good oral hygiene: Floss daily and brush twice a day with a soft-bristled toothbrush and fluoride toothpaste.
2. Avoid hard foods: Chewing ice, hard candy, or popcorn kernels can crack or dislodge a filling.
3. Limit sugary foods and drinks: Sugar feeds the bacteria that cause new decay, which can form around the edges of an existing filling.
4. Follow your dentist’s aftercare instructions: Following your dentist’s instructions helps your filling stay intact and last longer.
5. Address teeth grinding: If you grind your teeth in your sleep, talk to your dentist. Over time, grinding can wear down or crack fillings, and a night guard can protect them.
6. Avoid smoking: Smoking and other tobacco products increase the risk of gum disease and tooth decay, which can also affect your fillings.
7. Stay hydrated: Drinking plenty of water helps maintain saliva flow and washes away bacteria and food particles that can lead to new decay.
8. Regularly visit your dentist: Schedule professional cleanings and checkups at least twice a year so your dentist can check your fillings and catch problems early.

Frequently Asked Questions

Does getting a filling hurt?

Most people feel little to no pain during a filling because the area is numbed first. You may feel some pressure or vibration, and mild sensitivity afterward is normal for a few days.

Can a cavity heal without a filling?

Only in its earliest stage. When decay is limited to a weak spot in the enamel, fluoride and good oral hygiene can sometimes help the enamel remineralize. Once a cavity has formed a hole, it can’t heal on its own and needs to be treated by a dentist.

Is a filling permanent?

Fillings are long-lasting but not permanent. Over time, they can wear, crack, or develop new decay around the edges and may need to be replaced. Regular checkups help your dentist spot these issues early.

What happens if I don’t get a cavity filled?

The decay will continue to spread deeper into the tooth. Eventually it can reach the nerve, causing pain or infection that may require a root canal or extraction instead of a simple filling.

Dental Innovations: Your One-Stop Dental Care Destination

Looking for a dental practice that combines compassionate care and expertise? Based in Oklahoma City, we at Dental Innovations take pride in our professional and effective dental work, from routine fillings to general dental care for the whole family.

Contact us at 405-691-0877 or info@dentalinnovationsokc.com to schedule your appointment and discover why so many OKC families trust us with their smiles.

This article is for educational purposes only and does not replace a dental exam or diagnosis. If you have pain, swelling, or other concerns, please contact a dentist or doctor.

Sources

• American Dental Association – Fillings (MouthHealthy)
• American Dental Association – Dental Filling Options (Oral Health Topics)
• US Food and Drug Administration – Recommendations About the Use of Dental Amalgam in Certain High-Risk Populations (2020)
• National Institute of Dental and Craniofacial Research – Tooth Decay