Cavities are removed by drilling away the decayed portion of the tooth and replacing it with a filling material. The entire process typically takes 20 to 60 minutes per tooth, depending on the size and location of the cavity. While drilling remains the most common method, newer options like lasers and air abrasion can handle smaller cavities without the traditional drill.
Not Every Cavity Needs Drilling
Before any decay gets removed, your dentist determines whether the cavity actually requires physical intervention. The key factor is whether the tooth surface has fully broken through, creating a visible hole. A cavity that hasn’t yet penetrated the enamel can sometimes be managed without drilling, using strategies like fluoride treatments, dental sealants, or changes to brushing and diet that encourage the tooth to remineralize on its own.
Once the enamel is fully cavitated, though, the tooth can’t rebuild that lost structure on its own. The decay will keep progressing, so surgical removal becomes necessary. Your dentist may use X-rays, a physical probe, or both to assess how deep the decay extends and whether a simple filling will work or something more involved is needed.
For certain cases, particularly in children or patients who can’t tolerate drilling right away, a liquid called silver diamine fluoride can be applied directly to the cavity to halt its progression. The American Dental Association recognizes this as a valid non-restorative option for arresting advanced cavities on both baby teeth and permanent teeth. It doesn’t remove the decay or restore the tooth’s shape, but it buys time or serves as a solution when drilling isn’t practical.
The Step-by-Step Drilling Process
The procedure follows a predictable sequence. First, your dentist applies a numbing gel to the gum tissue around the affected tooth. This topical gel dulls the surface so you feel less of the injection that follows. After a minute or two, a local anesthetic (most commonly lidocaine) is injected into the gum near the tooth. Numbness typically sets in within two to four minutes.
Once you’re numb, the dentist uses a high-speed drill to remove the decayed enamel and dentin. The drill vibrates at extremely high speeds, and you’ll hear its characteristic whine, but you shouldn’t feel pain. You may feel pressure or vibration. The dentist works carefully to remove all the softened, damaged tooth structure while preserving as much healthy tooth as possible. For deeper cavities, they may switch to slower, more precise instruments as they get closer to the nerve.
After all the decay is cleared, the dentist shapes the remaining cavity so filling material can bond securely. They then place the filling, which could be tooth-colored composite resin, amalgam, or another material depending on the location and your preference. Finally, they polish the filling and have you bite down on articulating paper to check your bite alignment, making small adjustments until your teeth meet naturally.
Alternatives to Traditional Drilling
Dental lasers use a focused beam of light to cut away decay, producing less vibration and less pain than a traditional drill. For many patients, the appeal is obvious: less noise, less discomfort, and sometimes no need for anesthesia at all. That said, there’s limited evidence that lasers provide any long-term benefit to the tooth compared to conventional drilling, and not every cavity is a candidate for laser treatment.
Air abrasion works like a miniature sandblaster. A fine stream of tiny particles, usually made of silica, aluminum oxide, or a baking soda mixture, is propelled by compressed air at the decayed area. The particles knock loose the softened decay, and a suction tube removes the debris. It’s quiet, vibration-free, and works well for small, shallow cavities on the outer or chewing surfaces of teeth. It’s particularly popular for children and anxious patients with minimal decay.
Air abrasion has clear limitations. It can’t cut through hard enamel to reach decay underneath, can’t handle deep cavities near the nerve, and isn’t suitable for cavities between teeth. It also can’t prepare teeth for crowns or other major restorations. When the cavity is anything beyond small and superficial, a traditional drill is still the standard tool.
What Numbing Feels Like and How Long It Lasts
Lidocaine, the most widely used dental anesthetic, keeps the area numb for three to five hours, though the procedure itself is much shorter. That lingering numbness in your lip, cheek, or tongue is normal and gradually fades. Some dentists use longer-acting agents that can keep tissue numb for four to nine hours, which is more common for extensive work. Others choose shorter-acting options when a quick procedure doesn’t warrant hours of numbness afterward.
If you’re particularly anxious, your dentist may offer additional sedation options like nitrous oxide (laughing gas) or oral sedation on top of the local anesthetic. The local anesthetic blocks pain at the tooth itself, while sedation addresses the stress and fear of the experience.
Sensitivity After the Procedure
Some degree of tooth sensitivity after a filling is normal, especially to hot, cold, or sweet foods. This typically improves within a few days to a couple of weeks. If sensitivity lingers beyond two weeks but is gradually getting better, that’s generally not a concern.
Deeper fillings carry a higher risk of inflammation in the pulp, the soft tissue inside the tooth that contains nerves and blood vessels. This inflammation, called pulpitis, is more likely when the cavity was very deep, when the tooth has had multiple procedures over time, or when the tooth experienced trauma like a crack. Mild pulpitis often resolves on its own. If the pain is severe, worsening, or accompanied by swelling, the pulp may be infected or irreversibly damaged.
When a Filling Isn’t Enough
A standard filling works when the decay is confined to the outer layers of the tooth. When decay reaches the pulp, the inner chamber containing the nerve, a filling alone won’t solve the problem. At that point, a root canal is needed to remove the infected pulp tissue, clean the inside of the tooth, and seal it. The tooth is then typically capped with a crown for structural support.
The signs that decay has gone beyond filling territory include spontaneous throbbing pain (not just sensitivity to temperature), pain that wakes you at night, swelling in the gum near the tooth, or a persistent bad taste. Teeth that have cracked deeply enough to expose the pulp also fall into root canal territory regardless of how much visible decay is present.