How Do Dental Fillings Work?
Dental fillings are one of the most widely used treatments in dentistry, helping restore teeth affected by decay, cracks, or wear. They not only repair damage but also prevent further deterioration, allowing you to chew, speak, and smile comfortably.
But what exactly happens during a filling procedure? And how do these small restorations manage to strengthen and protect teeth for years? Let’s explore the full process—from diagnosis to aftercare—so you know exactly how dental fillings work.
Why Fillings Are Needed
The most common reason for getting a filling is to treat a cavity. Cavities develop when bacteria in your mouth produce acids that weaken and break down tooth enamel.
If not treated promptly, the decay can reach the dentin and eventually the pulp, leading to pain, infection, and possible tooth loss.
Aside from cavities, fillings can also be used to:
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Repair chipped or cracked teeth from injury or biting on hard food
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Restore worn teeth caused by grinding (bruxism) or erosion from acidic foods and drinks
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Replace old or broken fillings that are no longer effective
By sealing the damaged area, fillings protect the tooth from further bacterial invasion and restore its natural function.
The Science of Tooth Decay and Restoration
To appreciate how fillings work, it helps to understand the structure of a tooth:
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Enamel – The hard, outer layer that shields the tooth from decay and wear.
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Dentin – The softer layer underneath, which contains tiny tubules that connect to the tooth’s nerve.
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Pulp – The core of the tooth, housing nerves and blood vessels.
Once decay breaches the enamel, it spreads faster in the dentin due to its softer composition. Fillings interrupt this process by removing the decayed tissue and replacing it with a durable material that seals off the vulnerable area.
Step-by-Step: How a Dental Filling Is Done
Getting a filling is a straightforward process, usually completed in one dental appointment. Here’s what typically happens:
1. Examination and Diagnosis
Your dentist inspects the tooth visually and often uses X-rays to detect cavities that aren’t visible to the naked eye.
2. Numbing the Area
Local anaesthetic is applied to ensure you don’t feel pain during the procedure. While the area becomes numb, you may still feel some vibration or gentle pressure.
3. Removing the Damaged Area
A dental drill, laser, or air abrasion tool is used to carefully remove decayed or damaged tooth structure. The goal is to eliminate all affected tissue while keeping as much healthy enamel and dentin intact as possible.
4. Cleaning the Cavity
The empty space is cleaned thoroughly to remove any remaining debris and bacteria. In some cases, a protective liner may be placed to safeguard the tooth’s pulp.
5. Inserting the Filling Material
The chosen filling material is placed into the prepared space. For composite fillings, the material is applied in thin layers, each hardened with a special curing light.
6. Shaping and Polishing
Once the filling is set, the dentist shapes it to fit your bite and polishes the surface so it feels smooth and natural.
Types of Dental Fillings
Different filling materials are used depending on the tooth’s location, the size of the repair, and patient preference.
1. Amalgam Fillings
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Composition: A blend of metals such as silver, tin, copper, and mercury.
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Advantages: Highly durable and affordable.
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Drawbacks: Noticeable silver colour, may require more enamel removal.
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Best for: Back teeth that endure heavy chewing pressure.
2. Composite Resin Fillings
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Composition: Tooth-coloured resin mixed with fine glass particles.
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Advantages: Aesthetic and bonds directly to the tooth.
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Drawbacks: Not as long-lasting as amalgam.
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Best for: Front teeth or visible areas.
3. Ceramic (Porcelain) Fillings
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Advantages: Stain-resistant, natural appearance, strong.
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Drawbacks: More expensive, may require more than one visit.
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Best for: Patients prioritising aesthetics.
4. Glass Ionomer Fillings
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Advantages: Releases fluoride to protect against decay.
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Drawbacks: Less durable and less aesthetic.
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Best for: Non-chewing surfaces and children’s teeth.
5. Gold Fillings
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Advantages: Extremely durable, biocompatible.
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Drawbacks: Expensive and highly visible.
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Best for: People who prioritise longevity over appearance.
How Fillings Stay in Place
The method of attachment depends on the material:
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Amalgam relies on mechanical retention, where the dentist shapes the cavity so the filling locks in.
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Composite resin bonds chemically after the tooth surface is etched and coated with a bonding agent.
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Glass ionomer chemically adheres to the tooth while also providing fluoride release.
These bonding techniques ensure a secure seal that prevents bacteria from leaking into the tooth.
Lifespan of Dental Fillings
Fillings aren’t permanent, but with good care, they can last for many years:
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Amalgam: 10–15 years
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Composite resin: 5–10 years
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Ceramic: 10–15 years
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Glass ionomer: Up to 5 years
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Gold: 15–30 years
How long your filling lasts depends on the material used, your oral hygiene habits, and where the filling is located.
Aftercare and What to Expect
Following a filling, it’s common to experience:
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Numbness for a few hours from the anaesthetic
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Mild sensitivity to hot, cold, or pressure for a few days
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Tenderness in the jaw if the appointment was lengthy
These effects typically fade quickly. Persistent discomfort could indicate that your bite needs adjustment or that further treatment is required.
Caring for Fillings
To maximise the life of your dental filling:
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Use fluoride toothpaste to brush your teeth at least twice a day
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Floss daily to remove plaque between teeth
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Avoid biting down on hard objects like ice or pens
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Reduce sugary snacks and acidic beverages
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Schedule regular dental check-ups for early detection of wear or decay
Possible Complications
While dental fillings are safe, potential issues include:
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Allergic reactions to certain materials (rare)
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Filling breakage or loss due to excessive force
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Tooth fracture if decay was extensive
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Inflammation of the pulp, which requires additional treatment
Seeing a skilled dentist and maintaining good oral hygiene greatly reduces these risks.
The Future of Fillings
Dental technology is advancing rapidly. New materials are being developed that not only restore teeth but also help them heal. Promising innovations include:
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Bioactive fillings that release minerals to strengthen enamel
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Self-healing composites that repair minor cracks automatically
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Stem cell-based approaches to regrow dentin and enamel
These advancements could make future fillings stronger, longer-lasting, and more natural-looking than ever.
Final Thoughts
Dental fillings are more than just a patch-up job—they’re an essential part of modern dentistry, preserving teeth and preventing more serious oral health problems. By removing decay, sealing the tooth, and restoring its shape and function, fillings play a critical role in keeping your smile healthy.
Understanding how dental fillings work can help you feel more at ease during your next dental visit and inspire you to care for your teeth so you can make the most of every restoration.
