Getting a cavity filled is one of the most common dental procedures, and the entire process typically takes an hour or less. A simple, small filling can be done in as few as 20 minutes, while larger fillings or multiple fillings in one visit take longer. Here’s what happens at each stage, from the moment your dentist spots the cavity to the days after you leave the chair.
How Your Dentist Finds the Cavity
Before any filling work begins, your dentist needs to confirm that decay is present and determine how deep it goes. The primary method is a visual and tactile exam: your dentist dries the tooth surface, then uses a dental mirror and a small probe to check for changes in color, texture, and translucency that signal decay. This hands-on approach has been a cornerstone of clinical dentistry for over a century.
X-rays, particularly bitewing radiographs, are the most common detection aid beyond the visual exam. As a cavity progresses, the tooth loses mineral content in that area, which shows up as a dark spot on the X-ray. Combining the visual exam with X-rays significantly improves accuracy, especially for cavities forming between teeth where the probe can’t easily reach. Once your dentist confirms the cavity’s size and location, they can plan the filling.
Numbing the Tooth
The first step of the actual procedure is local anesthesia. Your dentist will likely start by applying a topical numbing gel to the gum tissue near the tooth. This gel works within about 30 seconds, with full surface numbness in two to three minutes, which makes the injection that follows much more comfortable.
The injection itself delivers a numbing agent, most commonly from a class of drugs called amides. These typically take effect within two to four minutes and last several hours. You’ll feel pressure but not pain during the procedure. The numbness in your lips, cheeks, and tongue can linger for three to five hours after you leave the office, sometimes longer depending on which agent your dentist uses.
Removing the Decay
Once the area is fully numb, your dentist uses a combination of specialized instruments (a small drill, laser, or air abrasion tool) to remove the damaged and decayed tissue from the tooth. The goal is to clear out all the softened, infected material while preserving as much healthy tooth structure as possible. You’ll hear the drill and feel vibration, but the numbing keeps this painless.
After the decay is removed, your dentist cleans the cavity to eliminate bacteria and debris. The resulting hole may be larger than you’d expect from the small spot visible on the surface, because decay often spreads wider once it gets past the hard outer enamel and into the softer layer underneath.
Preparing and Placing the Filling
What happens next depends on the filling material. For tooth-colored composite resin, the most widely used option today, the process involves a bonding step. Your dentist applies a mild acid solution to the cleaned tooth surface, a technique first developed in 1955. This acid etches, or slightly roughens, the enamel to create a microscopic texture that the filling material can grip. A liquid bonding agent is then painted on and acts as a glue layer between the tooth and the filling.
The composite resin is placed in the cavity in layers. After each layer, your dentist aims a special blue curing light at the material for several seconds, which triggers a chemical reaction that hardens it almost instantly. This layering approach helps reduce shrinkage and creates a stronger bond. For other materials like glass ionomer cement, the hardening process is different and doesn’t always require a curing light.
A 2026 World Health Organization guideline now recommends mercury-free filling materials, specifically glass ionomer cements and resin-based composites, as safe and effective alternatives to traditional silver amalgam. The guideline also flags safety considerations around resin-based materials, particularly limiting products containing certain chemical derivatives (like BPA-related compounds) for children, adolescents, and pregnant or breastfeeding women.
Shaping and Checking Your Bite
Once the filling is placed and hardened, your dentist shapes it to match the natural contours of your tooth. They’ll trim away any excess material, smooth rough edges, and polish the surface so it feels natural against your tongue. This step matters more than it might seem. Even a tiny high spot can throw off your bite and cause discomfort every time you chew.
Your dentist will ask you to bite down on a thin piece of colored paper that marks where your upper and lower teeth meet. If the filling sits even slightly too high, they’ll shave it down and recheck until the contact feels even. Don’t hesitate to speak up if something feels off. It’s much easier to adjust the filling while you’re still in the chair than to come back later.
What to Expect Afterward
With a composite (tooth-colored) filling, the material is fully hardened before you leave the office, so there’s no waiting period before the filling itself is ready for use. The main reason to hold off on eating is the numbness. Chewing while your mouth is still numb risks biting your cheek, tongue, or lip without realizing it. Once the feeling returns, you’re generally safe to eat normally.
For drinks, cool or room-temperature water is fine once the numbness fades. Hot beverages like coffee or tea are best avoided for two to three hours after a composite filling. Acidic drinks, sodas, and alcohol should wait about 24 hours to avoid irritating the area or interfering with the material’s final set.
Some sensitivity to hot, cold, sweet foods, or pressure from chewing is normal in the days following a filling. This typically fades within one to two weeks. Minor discomfort right around the tooth usually resolves within a day or two. If pain persists beyond a week, especially sharp pain when biting down, that’s a sign something needs adjustment, and a follow-up visit is warranted.
Why Fillings Sometimes Need Replacement
Fillings don’t last forever. Over years of chewing, temperature changes, and normal wear, a filling can crack, chip, or develop a gap between its edge and the tooth. Bacteria can seep into that gap and cause new decay underneath the old filling. Your dentist checks the condition of existing fillings during routine exams and will recommend a replacement when the seal is no longer holding. Composite fillings generally last 7 to 10 years, though some hold up longer with good oral care. Keeping up with brushing, flossing, and regular checkups is the simplest way to extend the life of any filling.