How a cavity gets treated depends entirely on how far the decay has progressed. Early-stage cavities, ones that haven’t broken through the enamel surface, can actually be reversed without any drilling at all. Once a cavity forms a visible hole, you’ll need a filling or a more involved procedure. Here’s what each stage looks like and what to expect from treatment.
Not All Cavities Need Fillings
The first visible sign of a cavity is a white spot on the tooth surface. At this stage, the enamel underneath has started losing minerals, but the surface itself is still intact. No hole exists yet, and no drilling is needed. The current professional consensus, reflected in guidelines from the American Dental Association and the International Caries Consensus Collaboration, is that early decay should be managed with non-invasive methods first: remineralization, better cleaning, and sealing. Restorative treatment (fillings) is recommended once the decay has created a cavity that can’t be reached by a toothbrush or floss.
This distinction matters because many people assume any dark spot or early sign of decay means an automatic filling. If your dentist catches it early enough, you may be able to stop and reverse the process entirely.
How Early Cavities Are Reversed
Remineralization is the process of restoring lost minerals to enamel before the surface breaks down. Fluoride is the most well-studied tool for this. When acid attacks enamel, it dissolves hydroxyapatite, the mineral that makes up tooth structure. If fluoride is present, the enamel rebuilds with a stronger mineral called fluorapatite, which resists future acid attacks better than the original.
Several fluoride delivery methods work at different concentrations:
- Toothpaste: Needs to contain at least 1,000 ppm fluoride to be effective. Most standard adult toothpastes meet this threshold.
- Mouth rinses: Available in daily-use (230 ppm) and weekly-use (900 ppm) formulations.
- Professional varnishes: Applied by a dentist, typically every three months for people at higher risk of cavities. This is the only professionally applied fluoride recommended for children under six.
- Professional gels: Contain a much higher fluoride concentration (12,300 ppm) and are applied in-office.
Beyond fluoride, a few other products can support remineralization. One contains casein phosphopeptide with amorphous calcium phosphate (often sold under the brand MI Paste), which releases calcium and phosphate directly into the layer of bacteria on your teeth, keeping conditions favorable for mineral repair. Research shows that combining these calcium-phosphate products with fluoride toothpaste enhances the remineralization effect, particularly for people with high cavity rates.
Silver Diamine Fluoride: A No-Drill Option
Silver diamine fluoride, or SDF, is a liquid painted directly onto a cavity to stop decay from progressing. The silver component kills cavity-causing bacteria, while the fluoride promotes remineralization. It also prevents the breakdown of the protein structure inside the deeper layer of the tooth. The ADA published its first-ever recommendations for SDF in 2018 as a recognized non-restorative treatment, and systematic reviews have confirmed it effectively arrests active cavities.
SDF is especially useful for people who can’t tolerate traditional dental procedures: very young children, older adults with limited mobility or access to dental care, and people with special needs. The major trade-off is cosmetic. SDF permanently stains the treated area black, making it a poor choice for visible front teeth in adults who care about appearance. But for a back molar or a baby tooth that’s going to fall out anyway, it can be a practical and painless solution.
What Happens During a Filling
Once decay has broken through the enamel and created an actual hole, a filling is the standard treatment. The procedure is straightforward: your dentist numbs the area with local anesthesia, removes the decayed tissue with a drill or laser, fills the space with a restorative material, hardens it with a curing light (for tooth-colored fillings), then polishes and adjusts your bite. Most fillings can be completed in a single appointment.
You have a few material options:
- Composite resin: The most popular choice today. It matches your tooth color, bonds directly to the tooth, and requires removing less healthy tooth structure. The downsides are that it can be harder to place in wet conditions and may not last quite as long as some alternatives, particularly on teeth that take heavy chewing force.
- Glass ionomer cement: Also tooth-colored and requires minimal removal of healthy structure, but it’s weaker than composite and unsuitable for large restorations. It’s often used for small cavities near the gum line or on baby teeth.
- Indirect restorations (crowns, inlays, onlays): Made from ceramic or gold, these are the most durable option and also the most expensive. They’re typically reserved for larger areas of damage where a standard filling wouldn’t hold up.
Laser Treatment as an Alternative to the Drill
If the sound or sensation of a dental drill is something you dread, laser cavity preparation is an option at some dental offices. Erbium lasers can remove decayed tooth structure with high precision and minimal damage to surrounding tissue. The biggest advantage for patients is comfort. Laser procedures are less invasive and often don’t require local anesthesia, which means no needles and no lingering numbness afterward. The technology has been used in dentistry since the 1990s, though it’s still not available at every practice and tends to cost more than conventional drilling.
When a Filling Isn’t Enough
If decay reaches the innermost part of the tooth, the pulp, you’ll feel it. The pulp contains the nerve and blood supply, and once bacteria invade this space, you’re looking at significant pain, sensitivity to hot and cold that lingers, and sometimes swelling. At this point, a filling can’t solve the problem because the infection is deeper than any filling material can reach.
A root canal removes the infected pulp tissue, cleans and disinfects the interior of the tooth, and seals it. You’ll then need a crown placed on top to protect the remaining structure. Out-of-network costs for a root canal range from roughly $620 to $1,500 depending on the tooth. Front teeth fall on the lower end of that range, while molars, which have more root canals to clean, fall on the higher end. The crown is an additional cost on top of that.
If the tooth is too damaged to save, or if the infection has spread to surrounding bone, extraction becomes the remaining option. The American Association of Endodontists frames this as a last resort, since keeping your natural tooth preserves jawbone density and avoids the need for an implant or bridge down the road.
How Decay Progresses if Left Untreated
Cavities don’t plateau on their own. A white spot becomes a micro-cavity in the enamel, which becomes a visible hole, which deepens into the dentin layer beneath. The tooth tries to protect itself by forming a barrier layer of new dentin over the pulp, but this defense has limits. Once bacteria reach the pulp, infection can spread beyond the tooth into the surrounding bone, forming an abscess. In rare but serious cases, untreated dental infections can cause cellulitis (a spreading soft-tissue infection) or even bone infection. Each stage of progression narrows your treatment options and raises the cost.
The practical takeaway is that timing determines your treatment. A cavity caught at the white-spot stage might need nothing more than fluoride varnish and better brushing habits. The same tooth six months later might need a filling. A year after that, a root canal. The biology doesn’t change, but the window for simpler, cheaper treatment closes steadily.