Dental Fillings: What They Are, How They Work & When You Need One

Dental fillings are one of the most common procedures in dentistry — and one of the most straightforward. If a cavity is caught early, a filling restores the tooth before the decay has a chance to spread deeper and turn into a bigger, more involved problem.

At Monaco Dentistry, we use tooth-colored composite resin fillings that blend in with your natural enamel. They look better, bond directly to the tooth, and allow us to preserve more of your healthy tooth structure compared to the older silver amalgam fillings many people grew up with.

How do you know you need a filling?

Sometimes you'll feel it — sensitivity to hot, cold, or sweets, or a sharp twinge when you bite down on a specific tooth. Other times, a cavity causes no symptoms at all and is only detected during a routine exam or on a digital X-ray. This is one of the strongest arguments for keeping up with regular dental visits: catching a small cavity early means a simple, conservative filling rather than a crown or root canal later.

Signs that may point to a cavity include sensitivity when eating or drinking something hot, cold, or sweet, a visible dark spot or hole in a tooth, food that consistently catches in the same area, and a rough or broken edge you can feel with your tongue.

What happens during a filling appointment

The process is simple and usually quick. After numbing the area so you're comfortable, your dentist removes the decayed portion of the tooth. The cavity is then cleaned and prepared, and composite resin is applied in thin layers. Each layer is hardened with a curing light before the next is added. Once the filling is shaped and polished, it's virtually invisible — matched to the shade of your surrounding teeth.

Most fillings are completed in 20 to 40 minutes, and you can eat and drink normally once the numbness wears off.

How long do fillings last?

Composite fillings typically last 5 to 10 years, and many last longer depending on their size, location, and how well you care for your teeth. Fillings on back teeth that bear heavy chewing forces tend to wear faster than those on front teeth. Good brushing, flossing, and regular checkups help your dentist monitor the integrity of your fillings over time and catch any issues early.

When a filling isn't enough

If the decay is too extensive — if it involves more than about half of the tooth's chewing surface — a filling alone may not provide the structural support the tooth needs. In those cases, your dentist may recommend an inlay, onlay, or a full crown to protect the remaining tooth from fracturing under biting pressure. This isn't an upsell; it's about matching the restoration to what the tooth actually requires.

Similarly, if decay has reached the inner nerve of the tooth (the pulp), a filling won't resolve the problem — that's when root canal therapy becomes necessary.

A word on replacing old silver fillings

If you have older amalgam fillings that are cracked, leaking, or showing signs of decay around the edges, they can be safely replaced with tooth-colored composite. Many patients also choose to replace them simply because they prefer the appearance. Your dentist can assess whether replacement is clinically necessary or elective and help you decide.

Quick FAQ

• Do fillings hurt? The area is numbed before treatment, so you shouldn't feel pain during the procedure. Mild sensitivity afterward is normal and usually fades within a few days.
• Can a filling fall out? It's uncommon, but fillings can loosen or dislodge over time, especially if you grind your teeth or bite into very hard foods. If it happens, contact your dentist — don't leave the tooth exposed.
• Are white fillings as strong as silver ones? Modern composite resins are durable and perform well for most cavities. For very large restorations on back molars, your dentist may discuss whether a different material or a crown is the better option.

‍