Fixing a cavity is one of the most common dental procedures, and the whole process typically takes 20 to 60 minutes depending on the size and location of the decay. Your dentist numbs the area, removes the damaged part of the tooth, fills the hole with a durable material, and shapes it to match your bite. Here’s what that looks like in practice.
How Your Dentist Finds the Cavity
Before any drilling happens, your dentist needs to determine exactly where the decay is and how deep it goes. A visual exam always comes first. Your dentist looks for discoloration, soft spots, or visible holes in the enamel. For cavities hiding between teeth or beneath the surface, X-rays are the standard next step. They reveal decay that isn’t visible to the naked eye, especially on the sides of teeth where they press together.
Some offices also use laser fluorescence devices, which detect early-stage mineral loss in enamel before a full cavity forms. These tools can catch decay at a point where it might still be reversible with fluoride treatment rather than a filling.
Numbing the Tooth
Most fillings start with a local anesthetic, almost always lidocaine, which is considered the gold standard in dentistry for its safety and effectiveness. Before the injection itself, many dentists apply a topical numbing gel to the gum so you feel less of the needle. Some practices also buffer the anesthetic with sodium bicarbonate, which speeds up the onset and reduces the sting of the injection.
If the cavity is very small and shallow, your dentist may skip the injection entirely, since the decay hasn’t reached the sensitive inner layers of the tooth. For most fillings, though, you’ll be fully numb within a few minutes and won’t feel anything beyond pressure during the procedure.
Removing the Decay
Once you’re numb, the dentist uses a high-speed drill or other specialized instruments to remove the decayed portion of the tooth. The goal is to clear away all the softened, damaged tissue while preserving as much healthy tooth structure as possible. You’ll hear the drill and feel vibration, but no pain.
Some dental offices now offer laser cavity removal as an alternative to the traditional drill. Lasers can safely and painlessly remove decay, and they’re especially popular with younger or anxious patients. One notable advantage: lasers are more precise, which means less healthy tooth is lost in the process. As one UCSF researcher put it, every filling weakens a tooth to some degree, so preserving natural structure is always the priority.
Filling the Tooth
After the decay is gone, the dentist cleans and dries the cavity, then fills it with a restorative material. The two most common options are composite resin (tooth-colored) and amalgam (silver-colored).
- Composite resin is the more popular choice today because it matches the color of your natural teeth. It’s applied in layers, and each layer is hardened with a special blue curing light. Composite fillings last up to 7 years on average.
- Amalgam fillings are the traditional silver option. They’re extremely durable and can last up to 15 years, making them a strong choice for back teeth that take heavy chewing force. They don’t require the layered curing process.
Once the filling is placed, the dentist shapes and polishes it to remove rough edges, then asks you to bite down on a thin piece of paper to check your bite alignment. If any spot feels too high, they’ll shave it down until it feels natural. This step matters more than it sounds. A filling that sits even slightly too high can cause ongoing discomfort when you chew.
When a Filling Isn’t Enough
Fillings work well for small to moderate cavities where most of the tooth structure is still intact. But if the decay has destroyed a large portion of the tooth, or if the tooth is cracked or weakened (especially after a root canal), a crown is the better option. A crown covers the entire visible portion of the tooth, providing structural support that a filling alone can’t offer. Your dentist makes this call based on how much healthy tooth remains after the decay is removed.
For cavities that fall somewhere in between, an inlay or onlay can bridge the gap. These are custom-made restorations that cover more surface area than a filling but less than a full crown.
What to Expect After the Procedure
The numbness from local anesthesia typically wears off within one to three hours. During that window, avoid eating or drinking hot or cold items, since you won’t be able to feel temperature and could burn yourself or bite your cheek. It’s best to wait at least two hours before eating anything at all.
Some sensitivity to hot, cold, or pressure is normal after a filling and usually fades within one to two weeks. If pain gets worse instead of better, lasts beyond three weeks, or the filled tooth feels too high when you bite down, that’s worth a call to your dentist. Swelling or fever after a filling is rare but signals a possible infection that needs prompt attention.
Treating Cavities Without Drilling
Not every cavity requires a drill. Very early cavities, where the enamel has started to weaken but hasn’t fully broken down, can sometimes be reversed with concentrated fluoride treatments. Your dentist may recommend prescription-strength fluoride toothpaste or in-office fluoride applications to help rebuild the mineral content of the enamel before a hole forms.
For cavities that have progressed beyond that point but where drilling isn’t ideal (in very young children or patients who can’t tolerate traditional procedures, for example), a topical solution called silver diamine fluoride can halt the decay. The silver component kills cavity-causing bacteria and stops the destruction, while the fluoride helps rebuild and strengthen the remaining tooth. It won’t restore the tooth’s original shape the way a filling does, and it does leave a dark stain on the treated area, but it can buy time or serve as a permanent solution when other options aren’t feasible.