Holes in teeth are cavities, and how they’re fixed depends entirely on how deep the damage goes. A small cavity caught early can be repaired in a single appointment with a filling, while a hole that has reached the nerve inside the tooth may need a root canal or, in the worst case, extraction. The good news is that the earliest stage of decay can actually be reversed before a hole even forms.
Why Depth Matters More Than Size
A tooth has three main layers: the hard outer enamel, a softer layer called dentin underneath, and the pulp at the center, which contains the nerve and blood supply. Decay works its way inward through these layers, and each stage calls for a different fix.
In the very first stage, minerals are just starting to leach out of the enamel. There’s no actual hole yet, just a white or brown spot. At this point, a professional fluoride treatment (a gel or varnish applied to the tooth) can push minerals back in and stop the process entirely. This is the only stage where the damage is fully reversible.
Once decay breaks through the enamel and creates a true hole, you’re past the point of reversal. A filling is the standard fix. If the hole deepens into the dentin layer, a filling may still work if it’s caught early, but larger areas of dentin damage often require a crown, a cap that covers the entire visible portion of the tooth. When decay reaches the pulp, the nerve becomes infected or irreversibly damaged, and a root canal is needed to remove the diseased tissue, clean the interior, and seal it. A crown is then placed over the tooth. If infection spreads and forms an abscess at the root tip, antibiotics may be needed alongside the root canal. In the most severe cases, the tooth has to be extracted.
Fillings: The Most Common Fix
For small to moderate cavities, your dentist will numb the area, remove the decayed material, and fill the hole. The two most common filling materials are composite resin (tooth-colored) and silver amalgam.
- Composite resin matches your natural tooth color, bonds directly to the tooth, and requires less removal of healthy structure. It lasts about 5 to 10 years on average.
- Silver amalgam is stronger and sometimes less expensive, but it doesn’t match tooth color and can create a grayish tint in surrounding tooth structure over time. It also requires removing more healthy tooth to create a space large enough to hold the filling, and it expands and contracts with temperature changes more than other materials, which can eventually lead to cracks. About 1% of people are allergic to the mercury in amalgam.
Most fillings are placed in a single appointment lasting 30 to 60 minutes. Expect some sensitivity for the first two days, with noticeable improvement by days three through five. Shallow to moderate fillings typically feel completely normal within two weeks. Deep fillings placed close to the nerve can take three to four weeks to settle down. Brief, fleeting sensitivity to hot or cold that lasts only a few seconds after the trigger is removed is normal during this healing window.
If your main complaint after a filling is pain when you bite down, the filling may be sitting slightly too high. This is a simple fix: your dentist can adjust the bite in minutes. Don’t wait it out if chewing pain persists beyond the first few days.
Crowns, Inlays, and Onlays for Larger Holes
Some cavities are too large for a filling to hold up. When a significant portion of the tooth is gone, a filling alone won’t provide enough structural support, and the remaining tooth walls can crack under chewing force. That’s where larger restorations come in.
An onlay covers the raised cusps on the chewing surface while preserving more of the natural tooth than a full crown. A crown caps the entire visible tooth and is the go-to option when the tooth is severely broken down or weakened. Crowns typically require two appointments: one to prepare the tooth and take impressions, and a second to cement the final restoration. Porcelain and porcelain-fused-to-metal crowns last 10 to 15 years on average, with newer zirconia crowns lasting at least as long due to their resistance to wear and fracture.
Cost varies widely. Crowns generally range from $500 to $3,000 per tooth depending on material and location. With dental insurance, the average drops to around $900. Without insurance, expect to pay closer to $1,300.
Root Canals: When the Hole Reaches the Nerve
A deep, throbbing toothache that lingers after exposure to hot or cold, pain that wakes you up at night, or swelling around the gum line are signs that decay has reached the pulp. At this point, you have two options: a root canal to save the tooth or extraction to remove it.
During a root canal, the infected pulp is removed, the interior of the tooth is cleaned and disinfected, and the empty space is filled and sealed. A crown is placed afterward to protect the remaining structure. The procedure itself is done under local anesthesia, and most people compare the experience to getting a large filling. Recovery is usually straightforward, with soreness fading within a few days.
Saving a natural tooth is almost always preferable to pulling it. An extraction means you’ll eventually need a bridge, implant, or denture to fill the gap, which adds cost and complexity. Root canals preserve your natural bite and chewing function.
A No-Drill Option for Some Cavities
Silver diamine fluoride, or SDF, is a liquid that can arrest active decay without any drilling. A dentist paints it directly onto the cavity, where the silver kills bacteria and the fluoride promotes remineralization of damaged tooth structure. The application takes just a few minutes, requires no anesthesia, and costs significantly less than a filling.
The major downside: SDF permanently stains the treated area black. It also has an unpleasant metallic taste and can irritate the gums. Because of the staining, it’s most commonly used on baby teeth in young children, back teeth that aren’t highly visible, or in situations where traditional drilling isn’t feasible. The American Dental Association’s expert panel recommends applying it twice a year for sustained benefit, since a single application isn’t enough to keep decay from progressing again.
SDF is cleared by the FDA as a treatment for tooth sensitivity, though its use for stopping cavities is technically off-label. It doesn’t restore the shape of the tooth or fill the hole. It simply stops the decay from getting worse, which can buy time or serve as a permanent solution when a traditional restoration isn’t an option.
What Over-the-Counter Kits Can and Can’t Do
Pharmacies sell temporary filling kits and dental repair materials. These products are designed as short-term patches to cover an exposed cavity or replace a lost filling until you can see a dentist. They are not permanent repairs. The FDA warns that long-term use of over-the-counter dental products intended as temporary fixes can lead to continuing irritation and other complications. If you use one, treat it as a bridge to a professional appointment, not a substitute for one.
Preventing New Holes From Forming
Cavities form when bacteria in your mouth feed on sugars and produce acid that dissolves tooth enamel. Fluoride toothpaste, flossing, and limiting sugary or acidic foods and drinks are the basics. But timing matters too: your saliva needs about 30 minutes after eating to neutralize acid and begin repairing enamel, so frequent snacking keeps your teeth in a constant acid bath.
Regular dental visits catch decay at the white-spot stage, when it can still be reversed with fluoride rather than drilled and filled. If you’re prone to cavities, your dentist may recommend prescription-strength fluoride rinses or sealants on your back teeth to add an extra layer of protection.